Dissertations / Theses on the topic 'LiDAR'

Tesi riguardante i LIDAR aviotrasportati mediante RPAS, cioè relativa alla realizzazione di rilievi LIDAR utilizzando come mezzo di trasporto dei sensori (Laser scanner, Piattaforma inerziale, ricevitore GPS) i droni. Nella trattazione, sono state affrontate le principali caratteristiche tecnologiche e funzionali dei vari strumenti impiegati nel rilievo LIDAR, cercando di comprenderne il ruolo individuale e la relativa sinergia.

Mapping is a central and common task in robotics research. Building an accurate map without human assistance provides several applications such as space missions, search and rescue, surveillance and can be used in dangerous areas. One application for robotic mapping is to measure changes in terrain volume. In Sweden there are over a hundred landfills that are regulated by laws that says that the growth of the landfill has to be measured at least once a year.

In this thesis, a preliminary study of methods for measuring terrain volume by the use of an Unmanned Aerial Vehicle (UAV) and a Light Detection And Ranging (LIDAR) sensor is done. Different techniques are tested, including data merging strategies and regression techniques by the use of Gaussian Processes. In the absence of real flight scenario data, an industrial robot has been used fordata acquisition. The result of the experiment was successful in measuring thevolume difference between scenarios in relation to the resolution of the LIDAR. However, for more accurate volume measurements and better evaluation of the algorithms, a better LIDAR is needed.

Kartering är ett centralt och vanligt förekommande problem inom robotik. Att bygga en korrekt karta av en robots omgivning utan mänsklig hjälp har en mängd tänkbara användningsområden. Exempel på sådana är rymduppdrag, räddningsoperationer,övervakning och användning i områden som är farliga för människor. En tillämpning för robotkartering är att mäta volymökning hos terräng över tiden. I Sverige finns det över hundra soptippar, och dessa soptippar är reglerade av lagar som säger att man måste mäta soptippens volymökning minst en gång om året.

I detta exjobb görs en undersökning av möjligheterna att göra dessa volymberäkningarmed hjälp av obemannade helikoptrar utrustade med en Light Detectionand Ranging (LIDAR) sensor. Olika tekniker har testats, både tekniker som slår ihop LIDAR data till en karta och regressionstekniker baserade på Gauss Processer. I avsaknad av data inspelad med riktig helikopter har ett experiment med en industri robot genomförts för att samla in data. Resultaten av volymmätningarnavar goda i förhållande till LIDAR-sensorns upplösning. För att få bättre volymmätningaroch bättre utvärderingar av de olika algoritmerna är en bättre LIDAR-sensor nödvändig.

Thesis (M.S. in Applied Mathematics)--Naval Postgraduate School, September 2009.
Thesis Advisor(s): Borges, Carlos F. ; Olsen, Richard C. "September 2009." Description based on title screen as viewed on 6 November 2009. Author(s) subject terms: LIDAR, Monte Carlo simulation, full-waveform, model. Includes bibliographical references (p. 105-108). Also available in print.

The ongoing development of self driving cars requires accurate measuring devices and the objective of this thesis was to investigate how di↵erent weather will affect one of these devices, known as a LiDAR. A LiDAR uses pulsed laser light to measure the distance to an object. The main goal of this thesis was to solve the transient radiative transfer equation (TRTE) that describes the propagation of radiation in a scattering, absorbing and emitting media. The TRTE was solved in the frequency domain using the discrete ordinate method (DOM) and a matrix formulation. An alternative model to estimate the amplitude of the return pulse is to use the LiDAR equation which describes the attenuation of a laser pulse in a similar way as Beer-Lamberts law. The difference between the models are that the TRTE accounts for multiple scattering whereas the LiDAR equation only accounts for single scattering. This has the effect that the LiDAR equation only models the change in amplitude of the return pulse whereas the TRTE also models the broadening and shift of the pulse. Experiments were performed with a LiDAR in foggy, rainy and clear weather conditions and compared with the theoretical models. The results from the measurements showed how the amplitude of the pulse decreased in denser fog. However, no tendency to a change in pulse shift and pulse width could be seen from the measured data. Additionally, the measurements showed the effect of ambient light and temperature to the LiDAR signal and also that, even after averaging 300 waveforms, noisy data were a problem. The results from the transient radiative transfer equation showed that in a medium with large optical depth the shift and width of the pulse are highly affected. It was also shown that the amplitude of the pulse calculated with the TRTE seemed to better approximate the experimental data in fog than the LiDAR equation.

I denna rapport har mätningar från en lidar och mätningar från en meteorologisk mätmast jämförts. En undersökning har även gjorts för vilka atmosfäriska tillstånd som lidarn mäter bra och för vilka förhållanden den mäter mindre bra. Som referens används data från en mätmast, som antas vara korrekta. Platsen för mätningarna är över skog vilket medför mer komplex terräng än över plan mark. Olika filter har utvecklats för de atmosfäriska tillstånd då lidarn mäter sämre, för att filtrera bort de mest extrema förhållandena. Dessa filter filtrerar bort data med för mycket turbulens, låg eller negativ vertikal vinddifferens och liten återspridning. När återspridningen är liten blir antalet mätningar även litet, därför har data med litet antalet mätningar också filtrerats. Lidarn har en inbyggd korrektion för moln, denna har också undersökts och ett filter har utvecklats för data som korrigeras fel. Efter att data har filtrerats visar jämförelser mellan lidarns uppmätta horisontella vindhastighet och mastens uppmätta horisontella vindhastighet en bättre korrelation och ett mindre relativt fel. För högre höjder fås en mindre skillnad i vindhastighet mellan lidarn och masten än för lägre höjder. Jämförelse av turbulensintensitet visar också en bättre korrelation. Antalet data som blivit bortfiltrerat p.g.a. atmosfäriska tillstånd är ca 12 % för 70 m, 96 m och 138 m, för 39 m har 22 % blivit bortfiltrerat. Utifrån filtrerade data har även två olika metoder för att bestämma friktionshastigheten undersökts. Det visade sig att metoderna gav olika resultat. Den ena metoden gav sämre korrelation men bättre 1:1 förhållande medan den andra metoden gav en bättre korrelation men lidarn visade något lägre friktionshastighet än mastens mätningar.

In this thesis, I demonstrate a single­photon Light Detection And Ranging, (LiDAR)system operating at 1550 nm capable of reconstructing 3D environments live withmm resolution at a rate of 400 points per second using eye­safe laser pulses. Thesystem was built using off­-the-­shelf optical components and analysis was performedusing open-­source software. I utilise a single superconducting nanowire single photondetector (SNSPD) with 19 ps time jitter and 85% detection efficiency to achieve a 4 psdepth resolution in live measurements. I also show that by performing slightly moretime costly post analysis of the data it is possible to increase the details and smoothnessof the images. Furthermore, I show that the same LiDAR system and much of the algorithms usedfor 3D LiDAR can be used to perform Optical Time Domain reflectrometry (OTDR)measurements. I demonstrate that the system can identify interfaces between differentrefractive mediums such as fibre to fibre or fibre to air couplings with a depth resolutionof 9 mm along a single line. Using these reflections, I also show that the systemcan identify flaws in optical fibres as well as measure certain characteristics suchas absorption coefficient due to Rayleigh scattering or thermal expansion. Lastly, Idemonstrate that the same OTDR principles used in fibres can be applied to free­s-paceoptical setups and that the system can identify specific optical elements as well asmeasure the quality of the alignment of an optical system.
I detta projekt demonstrerar jag ett enstaka foton Light Detection And Ranging,(LiDAR) system som använder ljus med 1550 nm våglängd som är ofarliga för ögon.Systemet kan återskapa 3D miljöer i realtid med 400 punkter per sekund med mmprecision. Systemet är byggt med kommersiellt tillgängliga komponenter och all dataanalys utfördes med open­source mjukvaran ETA. Jag använder en superconductingnanowire single photon detector, (SNSPD) med 19 ps timing jitter och 85 % effektivitetför att uppnå en precision på 4 ps i mätningarna. Jag visar också att genom utföramer tidskrävande post­analys av datan så är det möjligt att öka upplösningen ochjämnheten i bilderna. Utöver detta visar jag att samma LiDAR system och algoritmer kan användas för attutföra Optical Time Domain reflectrometry, (OTDR) mätningar. Jag visar att systemetkan urskilja olika reflektioner från fiber till fiber och fiber till luft kopplingar. Med hjälpav dessa reflektioner visar jag också att det är möjligt att identifiera brister i optiskafiber samt mäta olika egenskaper av fibern som absorbtions koeffcient eller termiskkontraktion. Slutligen visar jag att samma principer av OTDR som används i fiber kantillämpas till free­-space optiska system och att det är möjligt att identifera olika optiskaelement samt bedömma linjeringen av det optiska systemet.

The project at hand is an Automotive LiDAR Collision Avoidance System sponsored by Texas Instruments. The purpose of this project is to design and create a LiDAR system that utilizes Texas Instruments' technology to avoid forward collisions when mounted on a remote control car. The team is made up of six seniors from the University of Arizona of four different engineering disciplines including electrical, mechanical, computer, and optical engineering. The LiDAR Collision avoidance system is designed and built under a budget constraint of $4,000 and a non-negotiable completion deadline of May 1, 2017, otherwise known as Design Day.

In questa tesi, sono state realizzate tre diverse board: un DC-DC per il supply, un control unit per programmare i segnali d'ingresso del driver, un firing unit che contiene il chip principale(driver e GaN). Abbiamo usato il nitruro di galio perché è meglio adatto del silicio ad alte frequenze. L'obbiettivo principale è di raggiungere 50A di picco di corrente con soli 5ns di pulse. Sono stati usati Altium design per il disegno delle board e Ansys per l'evaluazione delle induttanze parassite. Questo ultimo crea diversi problemi e può limitare il raggiungimento del picco di corrente. Quindi bisogna fare il layout tenendo molta attenzione ai parassiti
In our three years of work, we have achieved the realization of a Firing unit board with the GaN and driver in a system in package. Three different boards were realized: A first board with only the resistor, the second one with the resistor and a shunt resistor and a third board with the laser diode and a shunt resistor. A DC-DC was realized for the supply while a control unit was realized for the control of the input signals of the driver.Unfortunately, no measurements of the firing unit have been done yet as we are still waiting for the chip to be completed. The DC-DC and the control unit board have been measured and tested. LIDAR application is the most attractive and efficient solution for this market. The challenges of LIDAR application consist in the development of the electronics generating a current pulse of 50A that lasts for less than 5ns. The technical area of this activity is fully autonomous self-driving car, and in particular what helps an autonomous vehicle to understand the world around it.

Les travaux présentés ici visent à améliorer la compréhension des impacts des aérosols sur le climat et la qualité de l’air et des interactions entre les aérosols et la vapeur d’eau. Pour répondre à ces enjeux scientifiques, de nouveaux moyens de télédétection active par lidar ont été développés, qui permettent la mesure des propriétés optiques des aérosols et du rapport de mélange en vapeur d’eau dans la basse et moyenne troposphère. Les études sur les propriétés optiques des aérosols ont été menées à partir du lidar à rétrodiffusion Rayleigh-Mie développé initialement par le LSCE et du lidar Raman-N2 développé dans le cadre de cette thèse en collaboration avec la société Leosphère. Elles ont permis de mieux caractériser les aérosols de pollution lors de la campagne été du programme MEGAPOLI (juillet 2009), les poussières désertiques lors de la campagne intensive du programme FENNEC (juin 2011), les feux de biomasse et les sels de mer lors des campagnes MACAMOZ (avril-mai 2009) et KAMASUTRA (août-septembre 2009) à bord du Marion Dufresne et les aérosols volcaniques émis lors de l’éruption de l’Eyjafjallajökull (avril-mai 2010). Une estimation des concentrations massiques en particules a pu être réalisée dans le panache de pollution parisien à partir des mesures de la campagne MEGAPOLI et dans le panache de cendres volcaniques de l’Eyjafjallajöjull grâce aux mesures au sol et aéroportées. Ces résultats montrent l’intérêt d’un réseau de lidars dans le domaine de la qualité de l’air pour l’amélioration des prévisions des modèles de chimie-transport par assimilation des profils de concentrations massiques. Le développement d’un lidar Raman vapeur d’eau, permettant la mesure du rapport de mélange en vapeur, ouvre également de nouvelles perspectives sur l’étude des interactions entre les aérosols et l’eau et en particulier sur l’hygroscopicité des aérosols.

L’objet de cette thèse est la conception d’un lidar dédié à la mesure du profil du contenu en eau liquide dans le brouillard. Actuellement, ce paramètre n’est mesuré que sur des volumes restreints, au sol ou à des altitudes données. Or sa connaissance devrait apporter une meilleure compréhension de l’évolution du brouillard et devrait aussi constituer une information intéressante pour le contrôle des modèles de prévision du phénomène. Elle est en théorie possible, car il a été montré à la fin des années 70 qu’il existe une relation empirique linéaire entre le contenu en eau liquide et le coefficient d’extinction optique pour une longueur d’onde de 11 μm. J’ai confirmé l’existence de cette relation sur la base d’observations récentes plus précises que celle des années 70, et ai déterminé ses limites de validité. Les brouillards se développent du sol jusqu’à quelques centaines de mètres, c’est donc sur cette gamme d’altitude que nous devons pouvoir faire la mesure. J’ai analysé les choix de conception offerts par les lidars afin de déterminer le système le plus performant pour notre application. Tout d’abord, j’ai analysé les capacités de mesure des lidars à détection directe et hétérodyne et j’ai mis en évidence que la détection hétérodyne est la plus appropriée. J’ai ensuite comparé les performances des configurations monostatique, bistatique et bistatique désaxé, et j’ai trouvé que la configuration monostatique est la plus appropriée. J’ai ensuite codé un simulateur instrumental et mis en évidence un biais de mesure lors de la restitution du coefficient d’extinction sur les premières centaines de mètres. J’ai proposé et validé une correction de ce biais. J’ai ensuite établi deux approximations analytiques pour le biais et l’écart-type de l’estimateur du coefficient d’extinction. Avec le simulateur, elles ont permis de se faire une idée de la portée et de la précision qui pourront être obtenues
The objective of the present study is the design of a lidar for the measurement of vertical profiles of liquid water content in fogs. Presently, there is no system able to measure such profile. The liquid water content is measured at ground or at limited number of altitudes. Yet, the information would improve our understanding of fog processes and provide valuable data for controlling fog forecast models. Its feasibility is theoretically possible because it was shown in the late 70s that the liquid water content and the optical extinction at 11μm are empirically linked by a linear relationship. My first objective was to test this relationship with rencent observations more precise than in the late 70s. The relationship is confirmed within limits that I tried to determine. The vertical extension of fogs is several hundreds of meters. We thus need a lidar with a maximum range of several meters. I compared the range of a direct versus a heterodyne lidar and I found the heterodyne lidar is more appropriate. I have developed analytic approximations of the heterodyne efficiency for several transmitter configurations - monostatic, bistatic with parallel or non-parallel axes - and found the monostatic configuration gives the best results at short range. I coded a simulator for the lidar and showed the retrieval of the extinction coefficient from lidar signals with the usual signal processing technique produces biases at short range. I proposed and validated a correction scheme. I derived two analytic approximations for the bias and the standard deviation of the estimations of the extinction coefficient. They were used to estimate the practical range and accuracy a lidar can achieve for the measurement of the liquid water content in fogs

With numerous applications in both military and civilian life, the demand for accurate 3D models of real world environments increases rapidly. Using an airborne laser scanner for the raw data acquisition and robust methods for data processing, the researchers at the Swedish Defence Research Agency (FOI) in Linköping hope to fully automate the modeling process.

The work of this thesis has mainly been focused on three areas: ground estimation, image segmentation and classification. Procedures have in each of these areas been developed, leading to a new algorithm for ground estimation, a number of segmentation methods as well as a full comparison of various decision values for an object based classification. The ground estimation algorithm developed has yielded good results compared to the method based on active contours previously elaborated at FOI. The computational effort needed by the new method has been greatly reduced compared to the former, as performance, particularly in urban areas, has been improved. The segmentation methods introduced have shown promising results in separating different types of objects. A new set of decision values and descriptors for the object based classifier has been suggested, which, according to tests, prove to be more efficient than the set p reviously used.

Med många tillämpningar både inom det civila och militära, ökar efterfrågan på noggranna och korrekta omvärldesmodeller snabbt. Forskare på FOI, Totalförsvarets Forskningsinstitut, arbetar med att fullt ut kunna automatisera den process som genererar dessa tredimensionella modeller av verkliga miljöer. En luftburen laserradar används för datainsamlingen och robusta metoder är under ständig utveckling för den efterföljande databehandlingen.

Arbetet som presenteras i denna rapport kan delas in i tre huvudområden: skattning av markyta, segmentering av data samt klassificering. Metoder inom varje område har utvecklats vilket lett fram till en ny algoritm för markestimering, en rad metoder för segmentering samt en noggrann jämförelse av olika beslutsvärden för en objektbaserad klassificering. Markskattningsalgoritmen har visat sig vara effektiv i jämförelse med en metod baserad på aktiva konturer som sedan tidigare utvecklats på FOI. Beräkningsbördan för den nya metoden är endast en bråkdel av den förra, samtidigt som prestandan, särskilt i urbana miljöer, har kunnat förbättras.

De segmenteringsmetoder som introducerats har visat på lovande resultat vad gäller möjligheten att särskilja olika typer av objekt. Slutligen har en ny uppsättning deskriptorer och beslutsvärden till den objektbaserade klassificeraren föreslagits. Den har enligt de tester som presenteras i rapporten visats sig vara mer effektiv än den uppsättning som använts fram till idag.

Approved for public release; distribution is unlimited
LIDAR has widely been used to create very accurate 3-D models for use in a wide range of commercial, governmental and nonprofit applications. This thesis identifies how recent advancements in Nd:YAG fiber lasers and InGaAs GmAPDs could be applied to space-borne missions, enabling low-cost solutions that fulfill NASA’s ICESat-2 and United States Geological Survey (USGS) objectives. An analysis of launch vehicles, standard spacecraft buses and payload technologies identified three potential low-cost solutions: one hosted aboard Iridium and two onboard a BCP2000 commercial bus. These systems were evaluated using NASA’s mass-based and aperture-based cost models to provide a rough estimate of cost versus NASA’s CALIPSO, ICESat-1 and ICESat-2 missions. Preliminary analysis shows a potential for these new technologies to outperform any previous space-based LIDAR mission. At $55M, the Iridium-hosted solution is 1/16th the cost of ICESat-2 at roughly one-third its capability. Two other solutions were estimated at $216.6M and $370.586M and provided over 3X and 10X the estimated capability of ICESat-2, respectively. Both systems are anticipated to fulfill NASA’s ice sheet and vegetation objectives while delivering a return on investment of roughly $1B per year based on USGS’s analysis of advanced 3-D data for the United States.

Approved for public release; distribution is unlimited
This paper analyzes new techniques used to extract 3D point clouds from airborne and satellite electro-optical data. The objective of this research was to compare the three types of point clouds to determine whether image point clouds could compete with the accuracy of LiDAR point clouds. The two main types of image point clouds are those created photogrammetrically, with two side-by-side images, or through feature matching between multiple images using multiview stereo techniques. Two software packages known for handling aerial imagery, IMAGINE Photogrammetry and Agisoft Photoscan Pro, were used to create such models. They were also tested with sub-meter resolution satellite imagery to determine whether much larger, but still truthful, models could be produced. It was found that neither software package is equipped to vertically analyze satellite imagery but both were successful when applied to aerial imagery. The photogrammetry model contained fewer points than the multiview model but maintained building shape better. While the photogrammetry model was determined to be the more accurate of the two it still did not compare to the accuracy of the LiDAR data.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California
A flexible system has been designed to accurately measure and average the outgoing laser energy of a micro-pulse LIDAR unit (MPL). This system incorporates specifically designed analog measurement circuitry interfaced with a microcontroller, allowing researchers to manage experiments from a personal computer. The final system produces a linearly proportional response between an incident laser energy input and the analog and digital circuitry’s output, accurate to within 0.1%. Custom designed algorithms allow the system to average the energy measured in a series of pulses. Each series can range on the order of tens of thousands of pulses.

In this thesis project, the main objective is to compare and evaluate different surveying methodsfor volume determination; Photogrammetry, Terrestrial Laser Scanning(TLS) and Aerial LaserScanning (ALS) based on time consumption, efficiency and safety in the mining industry. In addition,a volumetric computational method based on coordinates would be formulated to estimatethe volume of stockpiles using lidar data captured with a laser scanner. The use of GNSS receiver, UAV (Unmanned Aerial Vehicle) equipped with a LiDAR sensor as wellas a camera, and terrestrial laser scanner were adopted for making measurements on stockpiles. Trimble Business Center and Trimble RealWorks were used in processing LiDAR data from TLSand ALS. Two volume computational approaches were also explored using both TLS and ALSLiDAR data. Agisoft Photoscan was used in processing the images captured adopting the structurefrom motion principle. These softwares were used to estimate the volume of the stockpile. Matlabwas used to estimate the volume of stockpile using LiDAR data. A volume computational methodbased on coordinates of point cloud was implemented. Analysis based on time taken to captureand process all data types till the fi nal product was done. The results obtained from each datacapturing methods were evaluated. Simulated data technology is also adopted in this project asit can be modeled in different ways to study the effect of surface roughness (point density) onvolume estimated. A part of this project explores the use of MATLAB to  filter out unwantedpoint clouds coming from the weeds that grow on the surface of an abandoned stockpile and alsosurface areas that were to be excluded from the volume computation, as in this case. From the results obtained, TLS and ALS do not differ much in the  final volume estimated. Photogrammetry on the other-hand estimated a higher volume as compared to the other surveymethods. MATLAB in estimating the volume of stockpile achieves approximately an equal estimate as that of the TLS and ALS within a short period of time. The point density and fi ltering algorithm playsa critical role in volume computation which helps in providing a good estimate of the stockpile. Findings from this project show that is it time consuming to estimate the volume of stockpileusing TLS and Photogrammetric approach. In terms of safety on an active mining site, these twosurvey method have high risk probability as compared to the ALS approach. The accuracy forthe data captured and processed can be said to be satisfactory for each survey method.
I detta avhandlingsprojekt var huvudmålet att jämföra och utvärdera tre kartläggningsmetoder för volymbestämning: Fotogrammetri, Terrestrial Laser Scanning (TLS) och Aerial Laser Scan-ning (ALS) baserat på tidsförbrukning, effektivitet och säkerhet i gruvindustrin. Dessutom formulerades en volymetrisk beräkningsmetod baserad på koordinater för att uppskatta volymen av lager med hjälp av lidardata som fångats med en laserskanner. Användningen av GNSS-mottagare, UAV (obemannad flygbil) utrustad med en LiDAR-sensor samt en kamera och markbunden laserscanner antogs för att göra mätningar på lager. Trimble Business Center och Trimble RealWorks användes vid bearbetning av LiDAR-data från TLS och ALS. Två volymberäkningsmetoder undersöktes också med både TLS- och ALS LiDAR-data. Agisoft Photoscan användes vid bearbetning av de bilder som tagits och antagit strukturen från rörelseprincipen. Denna programvara användes för att uppskatta volymen på lagret. Matlab användes för att uppskatta volymen av lager med LiDAR-data. En volymberäkningsmetod baserad på koordinater för punktmoln implementerades i Matlab. Analys baserad på den tid det tar att fånga och bearbeta alla datatyper tills den slutliga produkten var klar. Resultaten från varje datafångstmetod utvärderades. Simulerad datateknik antas också i detta projekt eftersom den kan modelleras på olika sätt för att studera effekten av ytjämnhet (punkttäthet) på den uppskattade volymen. En del av detta projekt utforskar användningen av MATLAB för att filtrera bort oönskade punktmoln som kommer från ogräset som växer på ytan av ett övergivet lager och även ytarealer som skulle uteslutas från volymberäkningen, som i detta fall. Från de erhållna resultaten skiljer sig TLS och ALS inte mycket i de slutliga volymuppskattningarna. Fotogrammetri å andra sidan uppskattade en högre volym jämfört med de andra undersöknings-metoderna. MATLAB vid uppskattning av lagervolymen uppnår ungefär lika stor uppskattning som TLS och ALS inom en kort tidsperiod. Punkttätheten och filtreringsalgoritmen spelar en viktig roll i volymberäkning som hjälper till att ge en bra uppskattning av lagret. Resultat från detta projekt visar att det är tidskrävande att uppskatta lagervolymen med TLS och fotogram-metrisk metod. När det gäller säkerhet på en aktiv gruvplats har dessa två undersökningsmetoder hög risk sannolikhet jämfört med ALS-metoden. Noggrannheten för de insamlade och bearbetade uppgifterna kan sägas vara tillfredsställande för varje undersökningsmetod.

Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, September 2008.
Thesis Advisor(s): Agrawal, Brij N. ; Boger, Dan C. "September 2008." Description based on title screen as viewed on November 3, 2008. Includes bibliographical references (p. 79-80). Also available in print.

In forestry, natural forests are forest areas with high biodiversity, in need of preservation. The current mapping of natural forests is a tedious task that requires manual labor that could possibly be automated. In this paper we explore the main features used by a random forest algorithm to classify natural forest and managed forest in northern Sweden. The goal was to create a model with a substantial strength of agreement, meaning a Kappa value of 0.61 or higher, placing the model in the same range as models produced in previous research. We used raster data gathered from airborne LiDAR, combined with labeled sample areas, both supplied by the Swedish Forest Agency. Two experiments were performed with different features. Experiment 1 used features extracted using methods inspired from previous research while Experiment 2 further added upon those features. From the total number of used sample areas (n=2882), 70% was used to train the models and 30% was used for evaluation. The result was a Kappa value of 0.26 for Experiment 1 and 0.32 for Experiment 2. Features shown to be prominent are features derived from canopy height, where the supplied data also had the highest resolution. Percentiles, kurtosis and canopy crown areas derived from the canopy height were shown to be the most important for classification. The results fell short of our goal, possibly indicating a range of flaws in the data used. The size of the sample areas and resolution of raster data are likely important factors when extracting features, playing a large role in the produced model’s performance.

Upcoming missions to explore planetary bodies in the solar system will require accurate position and velocity data during descent in order to land safely at a predesignated site. A Doppler lidar instrument could provide measurements of the altitude, attitude, and velocity of the landing vehicle to supplement the data collected by other instruments. A flexible simulation tool would aid the tasks of designing and testing the functionality of such an instrument. LadarSIM is a robust parameterized simulation tool developed for time of flight lidar at Utah State University's Center for Advanced Imaging Ladar. This thesis outlines how LadarSIM was modified to include a simulation of Doppler lidar. A study is performed using LadarSIM to determine the effects of varying certain parameters of a Doppler lidar system. Point clouds of landing scenarios generated by the simulation with different scanning patterns are shown.

State-of-the-art LIDAR odometry techniques are exceptionally precise. However, while they solve the localization problem, they perform mapping on-the-run, not being able to close loops, neither re-localize in previously visited environments. This study is concerned with the development of a system that combines an accurate laser odometry estimator, with algorithms for place recognition in order to detect trajectory loops. This project uses widely available datasets from urban driving scenarios and outdoor areas for development and evaluation of the system The results obtained confirm that loop closure detection can significantly improve the accuracy and robustness of laser SLAM pipelines, with detectors based on point cloud segments and visual features displaying very strong performance during the evaluation phase.
Spjutspetsen inom Lidar-baserade teknik för fordonsodometri har den senaste tiden uppnått exceptionella nivåer av noggrannhet. Med det sagt har de metoder som presenterats fokuserat på att lösa lokaliseringsproblemet och därför gjort förenklande antaganden såsom att de sköter kartläggning av miljön löpande utan platsåterkoppling, och att de inte kan återlokalisera i tidigare kända miljöer. Således utvecklar vi i detta arbete ett system som kombinerar dessa noggranna lidarodometriska tekniker med algoritmer för platsigenkänning för att möjliggöra loopdetektion. Vi använder vitt tillgängliga dataset av körning i stadstrafik samt i utomhusområden för utveckling och utvärdering av systemet. Resultaten visar att platsåterkoppling förbättrar noggrannheten hos Lidar-baserade lokaliseringsmetoder och gör dem mer robusta, samt att man med hjälp av detektorer baserade på punktmolnssegmentering och visuella särdrag erhåller ett system som uppvisar mycket goda resultat under utvärderingsfasen.

O estudo desenvolvido nessa dissertação foi dividido em dois momentos. Na primeira parte foi apresentado a realização de uma calibração independente do sistema LIDAR Raman de vapor d\'água instalado no CLA seguindo uma metodologia desenvolvida na Howard University, baseada em uma análise cuidadosa da eficiência óptica dos componentes do sistema tendo como objetivo determinar essa eficiência e apresentar a resposta espectral do sistema. Após esse estudo, que permitiu obter um melhor entendimento da área instrumental do sistema, é apresentado, na segunda parte, uma análise preliminar das propriedades ópticas dos aerossóis na troposfera por meio da avaliação de alguns parâmetros como, por exemplo, os perfis verticais de extinção desses aerossóis, a LR e a SR, utilizando um sistema LIDAR Raman móvel desenvolvido pela Raymetrics Lidar Systems durante campanhas realizadas em alguns institutos de pesquisa no Estado de São Paulo.
The investigation reported in this dissertation has been divided in two parts. The first part was made to carry out an independent calibration of a Raman lidar system for water vapor in the CLA installed using a methodology that was developed at Howard University, based on a careful analysis of the efficiency of the optical system components aimed at determining the efficiency and displaying the spectral response of the system. After this study, which led to a better understanding of the field of instrumental system, the second part, presents a preliminary study of the optical properties of aerosols in the troposphere by evaluating parameters such as, for example, the vertical proles of aerosol extinction, SR and LR, using a mobile Raman LIDAR system developed by Raymetrics Lidar Systems, during campaigns conducted in some research institutes in the State of São Paulo.

La technique Lidar Radar est couramment utilisée pour la détection de cibles immergées dans des eaux peu profondes inférieures à quelques dizaines de mètres. Cette technique repose sur l’envoi d’un signal modulé associé, à la réception avec un filtre passe bande autour de la fréquence de modulation. Cette technique requiert ainsi un signal optique bleu vert, intense, modulé à des fréquences radar. Nous présentons dans cette thèse de nouvelles architectures de modulateur parfaitement adaptées à cette technique. La 1ère architecture est constituée d’une cavité externe comportant un doubleur intracavité. Cette architecture est couplée à une source laser picoseconde infrarouge (1064 nm). Les résultats ont montré que ce modulateur permet de générer un signal vert (532 nm), intense (5 mJ) et stable en fréquence. Grâce à la source utilisée, le signal modulé en sortie de l’émetteur (source laser et modulateur) ne dure que quelques nanosecondes. Ceci permet d’utiliser la méthode de « range-gating » pour obtenir une précision sur la localisation de la cible. Néanmoins, ce dispositif présente l’inconvénient d’avoir une bande passante du signal émis fixe. Nous avons donc développé une deuxième architecture du modulateur, permettant d’accorder facilement la bande passante du signal émis. Cette configuration repose sur le comportement polarimétrique des composants optiques afin de changer la largeur de bande passante du signal. Nous avons montré que ce modulateur permet de délivrer, un signal intense (jusqu’à 2,9 mJ), court (quelques nanosecondes), à 532 nm, modulé à des fréquences radar, stable en fréquence et accordable en bande passante
The Lidar Radar technique is commonly used for submerged target detection in shallow waters less than a few tens of meters. This technique is based on sending a modulated signal, associated with a bandpass filter around the modulation frequency after detection. This technique requires an intense blue-green optical signal modulated at radar frequencies. We present in this thesis new modulator architectures perfectly adapted to this technique. The first architecture consists of an external cavity with an intracavity SHG stage. This architecture is coupled to an infrared picosecond laser source (1064 nm). The results showed that this modulator makes it possible to generate a green signal (532 nm), intense (5 mJ) and stable in frequency. Thanks to the source used, the signal modulated at the output of the transmitter (laser source and modulator) lasts only a few nanoseconds. This makes it possible to use the "range-gating" method to precisely locate the target.Nevertheless, this device has the disadvantage of a fixed bandwidth. We have therefore developed a second architecture of the modulator, allowing to easily tune the bandwidth of the transmitted signal. This configuration is based on the polarimetric behavior of the optical components in order to change the bandwidth of the signal. We have shown that this modulator can deliver , an intense signal (up to 2.9 mJ), short (a few nanoseconds), at 532 nm, modulated at mirowave frequencies, stable in frequency and tunable in bandwidth

Expectations for turbine-mounted lidar are increasing. The installation of lidars in wind turbine nacelles for measuring incoming winds, preventing wind gusts and increasing energy productions is after recently studies, technically and economically feasible. Among available lidar types, the most studied were continuous wave lidars because they were the most reliable apparatus when this initiative began. However, after studying technical considerations and checking commercial lidars, it was found that pulsed lidarslead this technology due to their promising results. The purpose of this report is to fill the gap between the interest in this technology and the absence of any academic papers that analyzes continuous-wave and pulsed lidars forthe mounted lidar concept. Hence, this report discusses the importance of turbine mounted lidars for wind power industry, different possible configurations and explains why specifically pulsed lidars are becoming more important for the mounted lidarmarket.

En aquesta tesi doctoral es proposa utilitzar la tècnica LIDAR (Light Detection And Ranging) per estudiar la deriva de pesticides. A diferència dels col·lectors in situ, aquesta tècnica permet mesurar els aerosols de forma remota, amb elevada resolució temporal i en distància. Els objectius d’aquesta tesi són (1) dissenyar un sistema lidar específic per la mesura de la deriva i (2) avaluar la capacitat d’aquesta tècnica per quantificar la concentració en els núvols de pesticides. Per la consecució de l’objectiu (1) s’ha elaborat una metodologia de disseny, validada mitjançant la construcció d’un prototipus de ceilòmetre lidar biaxial. Partint d’aquesta metodologia s’han establert els paràmetres de disseny del sistema específic per mesurar la deriva: longitud d’ona de 1550 nm, energia per pols igual a 25 μJ, etc. Respecte a l’objectiu (2), es proposa un model teòric que relaciona les mesures lidar de la deriva amb les obtingudes utilitzant col·lectors passius. La relació entre els dos tipus de sensors també s’ha estudiat experimentalment. Les mesures van mostrar que per a cada assaig existeix una elevada correlació lineal (R2≈0.9) entre el senyal lidar i els col·lectors.
En esta tesis doctoral se propone utilizar la técnica LIDAR (LIght Detection And Ranging) para monitorizar la deriva de pesticidas. A diferencia de los colectores in situ, esta técnica permite medir los aerosoles de forma remota, con elevada resolución temporal y en distancia. Los objetivos de esta tesis son (1) diseñar un sistema lidar específico para la medida de la deriva y (2) evaluar la capacidad de esta técnica para cuantificar la concentración en las plumas de pesticidas. Para la consecución del objetivo (1) se ha elaborado una metodología de diseño, validada mediante la construcción de un prototipo de ceilómetro lidar biaxial. Partiendo de esta metodología se han establecido los parámetros de diseño del sistema lidar específico para medir la deriva: longitud de onda de 1550 nm, energía por pulso igual a 25 μJ, etc. Respecto al objetivo (2), se propone un modelo teórico que relaciona las medidas lidar de la deriva con las obtenidas utilizando colectores pasivos. La relación entre ambos tipos de sensores también ha sido estudiada experimentalmente. Las medidas mostraron que para cada ensayo existe una elevada correlación lineal (R2≈0.9) entre la señal lidar y los colectores.
This doctoral thesis proposes the use of the LIDAR (LIght Detection And Ranging) technique for spray drift monitoring. Unlike in situ collectors, this technique enables remote measurement of aerosols with high temporal and range resolution. The objectives of this thesis are as follows: (1) the design of a lidar system specifically for the remote sensing of pesticide spray drift and (2) assessment of the capacity of lidar technology to quantify droplet concentration in drift clouds. For the purposes of objective (1), a design methodology was elaborated. This methodology was validated with the construction of a biaxial lidar ceilometer prototype. Taking this methodology as a starting point the design parameters of a lidar system specifically for spray drift measurement were established: 1550 nm wavelength, 25 μJ de pulse energy, etc. As for objective (2), it is proposed a quantitative analytical model which relates the lidar spray drift measurements with those obtained using passive collectors. The relationship between the two sensor types was also studied experimentally. The measurements showed that for each test there is a high linear correlation (R2≈0.9) between the lidar signal and the collectors

Due to the unique environmental conditions and different feedback mechanisms, the Arctic region is especially sensitive to climate changes. The influence of clouds on the radiation budget is substantial, but difficult to quantify and parameterize in models. In the framework of the PhD, elastic backscatter and depolarization lidar observations of Arctic clouds were performed during the international Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) from Svalbard in March and April 2007. Clouds were probed above the inaccessible Arctic Ocean with a combination of airborne instruments: The Airborne Mobile Aerosol Lidar (AMALi) of the Alfred Wegener Institute for Polar and Marine Research provided information on the vertical and horizontal extent of clouds along the flight track, optical properties (backscatter coefficient), and cloud thermodynamic phase. From the data obtained by the spectral albedometer (University of Mainz), the cloud phase and cloud optical thickness was deduced. Furthermore, in situ observations with the Polar Nephelometer, Cloud Particle Imager and Forward Scattering Spectrometer Probe (Laboratoire de Météorologie Physique, France) provided information on the microphysical properties, cloud particle size and shape, concentration, extinction, liquid and ice water content. In the thesis, a data set of four flights is analyzed and interpreted. The lidar observations served to detect atmospheric structures of interest, which were then probed by in situ technique. With this method, an optically subvisible ice cloud was characterized by the ensemble of instruments (10 April 2007). Radiative transfer simulations based on the lidar, radiation and in situ measurements allowed the calculation of the cloud forcing, amounting to -0.4 W m-2. This slight surface cooling is negligible on a local scale. However, thin Arctic clouds have been reported more frequently in winter time, when the clouds' effect on longwave radiation (a surface warming of 2.8 W m-2) is not balanced by the reduced shortwave radiation (surface cooling). Boundary layer mixed-phase clouds were analyzed for two days (8 and 9 April 2007). The typical structure consisting of a predominantly liquid water layer on cloud top and ice crystals below were confirmed by all instruments. The lidar observations were compared to European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological analyses. A change of air masses along the flight track was evidenced in the airborne data by a small completely glaciated cloud part within the mixed-phase cloud system. This indicates that the updraft necessary for the formation of new cloud droplets at cloud top is disturbed by the mixing processes. The measurements served to quantify the shortcomings of the ECMWF model to describe mixed-phase clouds. As the partitioning of cloud condensate into liquid and ice water is done by a diagnostic equation based on temperature, the cloud structures consisting of a liquid cloud top layer and ice below could not be reproduced correctly. A small amount of liquid water was calculated for the lowest (and warmest) part of the cloud only. Further, the liquid water content was underestimated by an order of magnitude compared to in situ observations. The airborne lidar observations of 9 April 2007 were compared to space borne lidar data on board of the satellite Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). The systems agreed about the increase of cloud top height along the same flight track. However, during the time delay of 1 h between the lidar measurements, advection and cloud processing took place, and a detailed comparison of small-scale cloud structures was not possible. A double layer cloud at an altitude of 4 km was observed with lidar at the West coast in the direct vicinity of Svalbard (14 April 2007). The cloud system consisted of two geometrically thin liquid cloud layers (each 150 m thick) with ice below each layer. While the upper one was possibly formed by orographic lifting under the influence of westerly winds, or by the vertical wind shear shown by ECMWF analyses, the lower one might be the result of evaporating precipitation out of the upper layer. The existence of ice precipitation between the two layers supports the hypothesis that humidity released from evaporating precipitation was cooled and consequently condensed as it experienced the radiative cooling from the upper layer. In summary, a unique data set characterizing tropospheric Arctic clouds was collected with lidar, in situ and radiation instruments. The joint evaluation with meteorological analyses allowed a detailed insight in cloud properties, cloud evolution processes and radiative effects.
Die Arktis mit ihren speziellen Umweltbedingungen ist besonders empfindlich gegenüber Klimaveränderungen. Dabei spielen Wolken eine große Rolle im Strahlungsgleichgewicht, die aber nur schwer genau bestimmt und in Klimamodellen dargestellt werden kann. Die Daten für die Promotionsarbeit wurden im Frühjahr 2007 bei Flugzeug-Messungen von Wolken über dem Arktischen Ozean von Spitzbergen aus erhoben. Das dafür verwendete Lidar (Licht-Radar) des Alfred-Wegener-Instituts lieferte ein höhenaufgelöstes Bild der Wolkenstrukturen und ihrer Streu-Eigenschaften, andere Messgeräte ergänzten optische sowie mikrophysikalische Eigenschaften der Wolkenteilchen (Extinktion, Größenverteilung, Form, Konzentration, Flüssigwasser- und Eisgehalt, Messgeräte vom Laboratoire de Météorologie Physique, France) und Strahlungsmessungen (Uni Mainz). Während der Messkampagne herrschte Nordwind vor. Die untersuchten Luftmassen mit Ursprung fern von menschlichen Verschmutzungsquellen war daher sehr sauber. Beim Überströmen der kalten Luft über den offenen warmen Arktischen Ozean bildeten sich in der Grenzschicht (ca. 0-1500 m Höhe) Mischphasenwolken, die aus unterkühlten Wassertröpfchen im oberen Bereich und Eis im unteren Bereich der Wolken bestehen. Mit den Flugzeug-Messungen und numerischen Simulationen des Strahlungstransports wurde der Effekt einer dünnen Eiswolke auf den Strahlungshaushalt bestimmt. Die Wolke hatte lokal eine geringe Abkühlung der Erdoberfläche zur Folge. Ähnliche Wolken würden jedoch im Winter, wenn keine Sonnenstrahlung die Arktis erreicht, durch den Treibhauseffekt eine nicht vernachlässigbare Erwärmung der Oberfläche verursachen. Die Messungen der Mischphasenwolken wurden mit einem Wettervorhersagemodell (ECMWF) verglichen. Für die ständig neue Bildung von flüssigen Wassertropfen im oberen Teil der Wolke ist das Aufsteigen von feuchten Luftpaketen nötig. Während einer Messung wurden entlang der Flugstrecke verschiedene Luftmassen durchflogen. An der Luftmassengrenze wurde eine reine Eiswolke inmitten eines Mischphasen-Systems beobachtet. Die Messungen zeigen, dass das Mischen von Luftmassen den Nachschub an feuchter Luft blockiert, was unmittelbare Auswirkungen auf die thermodynamische Phase des Wolkenwassers hat. Weiterhin wurde bestimmt, wie groß die Abweichungen der Modellrechnungen von den Messungen bezüglich Wassergehalt und der Verteilung von Flüssigwasser und Eis waren. Durch die vereinfachte Wolken-Parameterisierung wurde die typische vertikale Struktur von Mischphasenwolken im Modell nicht wiedergegeben. Die flugzeuggetragenen Lidar-Messungen vom 9. April 2007 wurden mit Lidar-Messungen an Bord des Satelliten CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) verglichen. Die Messungen zeigten beide eine ansteigende Wolkenobergrenze entlang desselben Flugwegs. Da die Messungen jedoch nicht genau gleichzeitig durchgeführt wurden, war wegen Advektion und Prozessen in den Wolken kein genauer Vergleich der kleinskaligen Wolkenstrukturen möglich. Außerdem wurde eine doppelte Wolkenschicht in der freien Troposphäre (4 km Höhe) analysiert. Die Wolke bestand aus zwei separaten dünnen Schichten aus flüssigem Wasser (je 150 m dick) mit jeweils Eis darunter. Die untere Schicht entstand wahrscheinlich aus verdunstetem Eis-Niederschlag. Diese feuchte Schicht wurde durch die Abstrahlung der oberen Wolkenschicht gekühlt, so dass sie wieder kondensierte. Solche Wolkenformationen sind in der Arktis bisher vor allem in der Grenzschicht bekannt. Ein einzigartiger Datensatz von arktischen Wolken wurde mit einer Kombination verschiedener Flugzeug-Messgeräte erhoben. Zusammen mit meteorologischen Analysen konnten für verschiedene Fallstudien Wolkeneigenschaften, Entwicklungsprozesse und Auswirkungen auf den Strahlungshaushalt bestimmt werden.

Den här rapporten har utrett möjligheten att automatiskt identifiera diken frånflygburet insamlat LiDAR-data. Den metod för identifiering som har valts harförst skapat en höjdbild från LiDAR-data. Därefter har den tagit fram kandidatertill diken genom att vektorisera resultatet från en linjedetektering. Egenskaper-na för dikeskandidaterna har sedan beräknats genom en analys av höjdprofilerför varje enskild kandidat, där höjdprofilerna skapats utifrån ursprungliga data.Genom att filtrera kandidaterna efter deras egenskaper kan dikeskartor med an-vändarspecificerade mått på diken presenteras i ett vektorformat som underlättarvidare användning. Rapporten beskriver hur algoritmen har implementerats ochpresenterar också exempel på resultat. Efter en analys av algoritmen samt förslagpå förbättringar presenteras den viktigaste behållningen av rapporten; Att det ärmöjligt med automatisk detektering av diken.
This Master’s thesis is investigating the possibility of automatically identifyingditches in airborne collected LiDAR data. The chosen approach to identificationcommences by creating an elevation picture from the LiDAR data. Then it usesthe result of a line detection to exhibit candidates for ditches. The properties forthe various candidates are calculated through an analysis of the elevation profile forthe candidates, where the elevation profiles are created from the original data. Byfiltering the candidates according to their calculated properties, maps with ditchesconforming to user-specified limits are created and presented in vector format.This thesis describes how the algorithm is implemented and gives examples ofresults. After an analysis of the algorithm and a proposal for improvements, itis suggested that automatic detection of ditches in LiDAR collected data is anachievable objective.

Autonomous driving is the concept of a vehicle that operates in traffic without instructions from a driver. A major challenge for such a system is to provide a comprehensive, accurate and compact scene model based on information from sensors. For such a model to be comprehensive it must provide 3D position and semantics on relevant surroundings to enable a safe traffic behavior. Such a model creates a foundation for autonomous driving to make substantiated driving decisions. The model must be compact to enable efficient processing, allowing driving decisions to be made in real time. In this thesis rectangular objects (The Stixelworld) are used to represent the surroundings of a vehicle and provide a scene model. LIDAR and semantic segmentation are fused in the computation of these rectangles. This method indicates that a dense and compact scene model can be provided also from sparse LIDAR data by use of semantic segmentation.
Fullt självkörande fordon behöver inte förare. Ett sådant fordon behöver en precis, detaljerad och kompakt modell av omgivningen baserad på sensordata. Med detaljerad avses att modellen innefattar all information nödvändig för ett trafiksäkert beteende. Med kompakt avses att en snabb bearbetning kan göras av modellen så att fordonet i realtid kan fatta beslut och manövrera i trafiken. I denna uppsats tillämpas en metod där man med rektangulära objekt skapar en modell av omgivningen. Dessa beräknas från LIDAR och semantisk segmentering. Arbetet indikerar att med hjälp av semantisk segmentering kan en tät, detaljerad och kompakt modell göras även från glesa LIDAR-data.

The monitoring and study of the earth�s atmosphere is becoming an increasingly important task given the current uncertainties in climate prediction. Areas where lidar has been used to further understanding of the atmosphere include monitoring of greenhouse gases, global warming, stratospheric ozone depletion, photochemical smog and aerosol photochemistry. However, the potentially severe long term effects of anthropogenic aerosols on earth�s biosphere are poorly understood. This project seeks to apply state of the art laser technology to develop an innovative multiwavelength lidar system capable of providing new information and new insights into the field of tropospheric aerosol lidar. Several novel tunable laser and laser-like sources have been investigated and developed for the purpose of tropospheric aerosol lidar at The National Institute of Water and Atmospheric Research (Niwa), Central Otago. Multiwavelength operation in the visible and near infrared portion of the spectrum has been emphasised with the sources developed collectively spanning the wavelength interval of 400-1369 nm. The laser sources investigated were the LiF:F2+ colour centre, Titanium Sapphire (Ti:sapphire) and barium nitrate Raman lasers. In addition to the laser sources, the β-barium borate optical parametric oscillator (BBO OPO) was characterised. For each of the sources, lidar relevant aspects were studied. The results recorded include conversion efficiency with respect to the pump source, linewidth and tuning characteristics, beam quality, temporal behaviour, and device reliability and ruggedness. It was found that the LiF:F2+ laser offered significantly lower threshold, broader tuning and higher output pulse energies than the Ti:sapphire laser in the 900-1000 nm region. The high optical gain of the LiF:F2+ medium facilitated cavity optical alignment and operation of the system. The high gain also resulted in temporal behaviour well suited to the existing Niwa lidar detection scheme. When using a 5 ns pump source, amplified spontaneous emission (ASE) was found to limit the laser tuning range and efficiency. The barium nitrate Raman laser was based on a simple linear cavity arrangement which resulted in a compact and robust device with no moving components. The stimulated Raman scattering process offers relatively narrow linewidth laser operation at the first and second Stokes wavelengths of 1197 nm and 1369 nm respectively. This laser offered efficient operation once the high operation threshold was reached. Second harmonic generation was used to extend the number of potential lidar transmitter lines produced. The barium nitrate Raman laser possessed high beam divergence and a maximum of three discrete transmitter wavelengths. The BBO OPO used a type I collinear signal resonant configuration. A plane-plane cavity configuration with pump reflection was found to provide simplicity of design, low threshold, highly efficient operation and output pointing stability. The BBO OPO signal wavelength could be tuned over the wavelength interval of 400-700 nm. The disadvantage of the plane cavity was high output beam divergence. However, this was successfully brought within the required limits through the use of a 40 mm long cavity in conjunction with an expanding and collimating telescope. As a result of the study, a Tunable lidar Transmitter (TLT) system based on the BBO OPO was designed and constructed at the Physics Department. The TLT was computer-controlled using custom written software and constructed in a self contained modular manner with all required mechanical, electrical and optical components. A user manual was also written to accompany the TLT. The TLT was installed at Niwa and was successfully used to gather preliminary multiwavelength lidar data. The TLT BBO OPO threshold occurred for a pump energy of 5.2 mJ (10.6 MW/cm2) and had a maximum slope efficiency of 53%. Signal efficiency varied from 24-41-35% over the intervals of 410-500-600 nm. A maximum signal energy of 21 mJ was obtained for a signal wavelength of 492 nm when using the maximum available pump energy of 42 mJ. OPO signal linewidth varied from 0.1-1-8 nm over the signal wavelength intervals of 400-600-700 nm. The associated OPO finesse varied between 370 and 100 as the signal wavelength was tuned over the wavelength interval of 400-600 nm. The temporal behaviour of the BBO OPO was a slowly varying function of pump energy and closely followed the temporal behaviour of the pump laser, making it well suited to the existing Italian lidar detection and timing scheme.

Although savanna ecosystems cover approximately 20 % of the terrestrial land surface and can have productivity equal to some closed forests, their role in the global carbon cycle is poorly understood. This study explored the applicability of a past spaceborne Lidar mission and the potential of future missions to estimate canopy height and carbon storage in these biomes.

The research used data from two Oak savannas in California, USA: the Tejon Ranch Conservancy in Kern County and the Tonzi Ranch in Santa Clara County. In the first paper we used non-parametric regression techniques to estimate canopy height from waveform parameters derived from the Ice Cloud and land Elevation Satellite’s Geoscience Laser Altimeter System (ICESat-GLAS) data. Merely adopting the methods derived for forests did not produce adequate results but the modeling was significantly improved by incorporating canopy cover information and interaction terms to address the high structural heterogeneity inherent to savannas. Paper 2 explored the relationship between canopy height and aboveground biomass. To accomplish this we developed generalized models using the classical least squares regression modeling approach to relate canopy height to above ground woody biomass and then employed Hierarchical Bayesian Analysis (HBA) to explore the implications of using generalized instead of species composition-specific models. Models that incorporated canopy cover proxies performed better than those that did not. Although the model parameters indicated interspecific variability, the distribution of the posterior densities of the differences between composition level and global level parameter values showed a high support for the use of global parameters, suggesting that these canopy height-biomass models are universally (large scale) applicable.

As the spatial coverage of spaceborne lidar will remain limited for the immediate future, our objective in paper 3 was to explore the best means of extrapolating plot level biomass into wall-to-wall maps that provide more ecological information. We evaluated the utility of three spatial modeling approaches to address this problem: deterministic methods, geostatistical methods and an image segmentation approach. Overall, the mean pixel biomass estimated by the 3 approaches did not differ significantly but the output maps showed marked differences in the estimation precision and ability of each model to mimic the primary variable’s trend across the landscape. The results emphasized the need for future satellite lidar missions to consider increasing the sampling intensity across track so that biomass observations are made and characterized at the scale at which they vary.

We used data from the Multiple Altimeter Beam Experimental Lidar (MABEL), an airborne photon counting lidar sensor developed by NASA Goddard to simulate ICESat-2 data. We segmented each transect into different block sizes and calculated canopy top and mean ground elevation based on the structure of the histogram of the block’s aggregated photons. Our algorithm was able to compute canopy height and generate visually meaningful vegetation profiles at MABEL’s signal and noise levels but a simulation of the expected performance of ICESat-2 by adjusting MABEL data's detected number of signal and noise photons to that predicted using ATLAS instrument model design cases indicated that signal photons will be substantially lower. The lower data resolution reduces canopy height estimation precision especially in areas of low density vegetation cover.

Given the clear difficulties in processing simulated ATLAS data, it appears unlikely that it will provide the kind of data required for mapping of the biophysical properties of savanna vegetation. Rather, resources are better concentrated on preparing for the Global Ecosystem Dynamics Investigation (GEDI) mission, a waveform lidar mission scheduled to launch by the end of this decade. In addition to the full waveform technique, GEDI will collect data from 25 m diameter contiguous footprints with a high across track density, a requirement that we identified as critically necessary in paper 3. (Abstract shortened by UMI.)

As more data sources have become abundantly available, an increased interest in 3D reconstruction has emerged in the image processing academic community. Applications for 3D reconstruction of urban and residential buildings consist of urban planning, network planning for mobile communication, tourism information systems, spatial analysis of air pollution and noise nuisance, microclimate investigations, and Geographical Information Systems (GISs). Previous, classical, 3D reconstruction algorithms solely utilized aerial photography. With the advent of LIDAR systems, current algorithms explore using captured LIDAR data as an additional feasible source of information for 3D reconstruction. Preprocessing techniques are proposed for the development of an autonomous 3D Reconstruction algorithm. The algorithm is designed for autonomously deriving three dimensional models of urban and residential buildings from raw LIDAR data. First, a greedy insertion triangulation algorithm, modified with a proposed noise filtering technique, triangulates the raw LIDAR data. The normal vectors of those triangles are then passed to an unsupervised clustering algorithm – Fuzzy Simplified Adaptive Resonance Theory (Fuzzy SART). Fuzzy SART returns a rough grouping of coplanar triangles. A proposed multiple regression algorithm then further refines the coplanar grouping by further removing outliers and deriving an improved planar segmentation of the raw LIDAR data. Finally, further refinement is achieved by calculating the intersection of the best fit roof planes and moving nearby points close to that intersection to exist at the intersection, resulting in straight roof ridges. The end result of the aforementioned techniques culminates in a well defined model approximating the considered building depicted by the LIDAR data.
M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 111-120).
It is no wonder that research in Si photonics (optical components embedded on a silicon platform) has bloomed so rapidly the last few years. Combining low loss, strong refractive index contrast (and, thus, light confinement), with electro-optical and thermo-optical effects, allows for the fabrication of dense and complex electro-optical Si photonics systems. Moreover, because it is based on the well-established platforms of the CMOS industry, Si photonics is expected to rapidly shift from a research field to the production of high volume, low cost, complex, integrated electro-optical systems. One class of systems receiving increasing interest are Nanophotonic Phased Arrays (NPAs), which offer free space emission of a manipulated beam that can be steered, focused, have controlled angular momentum and even create holograms. Still, some substantial challenges remain in applying these NPAs to real systems. Large cell size and spacing between adjacent antennas produce multiple beams and reduce effective steering angle. In addition, small beam angle requirements and large aperture in NPAs receivers demand large phased array size. In order to allow for both steering angle and large aperture, a large array with small cell size is required resulting large number of unit cells in one array. In this work, we first propose two metallic nanoantennas to couple between a waveguide mode to free space radiation. Then, by combining existing Si photonic components like directional couplers and modulators with optical antennas and phase shifters that were designed for this goal we demonstrate, in this work, several NPAs for various applications. Using unique architecture, we then, specifically focus on a, NPA based, lidar. These lidar systems are essential components in any autonomous system maneuvering in an undefined environment. An on chip lidar like this one can serve, for example, in the automotive industry for safety enhancement and to allow autonomous driving functionality at an affordable price.
by Ami Yaacobi.
Ph. D.

Third generation full-waveform (FW) LIDAR systems image an entire scene by emitting laser pulses in particular directions and measuring the echoes. Each of these echoes provides range measurements about the objects intercepted by the laser pulse along a specified direction. By scanning through a specified region using a series of emitted pulses and observing their echoes, connected 1D profiles of 3D scenes can be readily obtained. This extra information has proven helpful in providing additional insight into the scene structure which can be used to construct effective characterizations and classifications. Unfortunately, massive amounts of data are typically collected which impose storage, processing and transmission limitations. To address these problems, a number of compression approaches have been developed in the literature. These, however, generally require the initial acquisition of large amounts of data only to later discard most of it by exploiting redundancies, thus sampling inefficiently. Based on this, our main goal is to apply efficient and effective LIDAR sampling schemes that achieve acceptable reconstruction quality of the 3D scenes. To achieve this goal, we propose on using compressive sampling by emitting pulses only into random locations within the scene and collecting only the corresponding returned FW signals. Under this framework, the number of emissions would typically be much smaller than what traditional LIDAR systems require. Application of this requires, however, that scenes contain many degrees of freedom. Fortunately, such a requirement is satisfied in most natural and man-made scenes. Here, we propose to use a measure of rank as the measure of degrees of freedom. To recover the connected 1D profiles of the 3D scene, matrix completion is applied to the tensor slices. In this paper, we test our approach by showing that recovery of compressively sampled 1D profiles of actual 3D scenes is possible using only a subset of measurements.

Orientador: Ana Maria Canesqui
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-08-08T02:33:53Z (GMT). No. of bitstreams: 1 Barsaglini_ReniAparecida_D.pdf: 2563294 bytes, checksum: 459d247bf4af378f145f27acb0b7dc16 (MD5) Previous issue date: 2006
Resumo: Este estudo analisa as representações sociais e a experiência com o diabetes mellitus, articulando a dimensão simbólica, a partir dos significados e do sentido atribuído à enfermidade, e a dimensão concreta do seu gerenciamento. A investigação é pertinente devido à importância epidemiológica do diabetes no quadro sanitário brasileiro, à escassez de pesquisas sobre as enfermidades ou as condições crônicas na área de Antropologia e Saúde, além de se constituir em oportunidade para articular os planos micro e macroanalíticos no estudo do adoecimento. Foi empregada a metodologia qualitativa, na perspectiva socioantropológica, combinando as técnicas da pesquisa documental, da entrevista, do relato oral e da observação em campo (bairros, residências, serviços de saúde) para coletar as informações sobre as quais se procedeu, posteriormente, a análise temática. A análise dos dados sobre o saber biomédico e os modelos de intervenção baseou-se em textos básicos sobre o assunto e em documentos oficiais normativos sobre a atenção dirigida ao diabetes, complementando-se com os discursos dos adoecidos com a enfermidade, de não-adoecidos e de profissionais de saúde que atendem os diabéticos. Pela abordagem que se designou ¿construtivista integradora¿, para a qual a realidade social é constituída pelas práticas interacionais e interpretativas, mas também pela participação de elementos da estrutura social, as representações sociais e a experiência da enfermidade foram tomadas articuladamente numa relação de influência circular como componentes do processo de adoecimento, relativizando, dessa forma, tanto a determinação social ou cultural quanto a total autonomia/liberdade do indivíduo. O conceito de representações sociais valeu-se da sociologia francesa com a abordagem herzlichiana, e a experiência da doença respaldou-se no suporte fenomenológico. Concluiu-se, neste estudo, que as formas como o adoecido pensa e lida com o diabetes envolvem fatores de ordem estrutural, simbólica, do contexto da vida diária, da biografia do sujeito, da experiência (prévia e atual, pessoal e de outras pessoas) e do próprio curso da doença. Os profissionais de saúde, embora imbuídos pelo discurso médico-científico, reinterpretam o saber erudito sobre o diabetes no exercício de sua prática, a partir da experiência (profissional e pessoal), passando-a pelo crivo das representações. Em ambos os segmentos, o adoecimento mobiliza saberes e práticas que, reciprocamente, são reelaborados em função da experiência, das representações e pela intermediação dos elementos contextuais
Abstract: The study analyzed the social representations and experience with diabetes, articulating the symbolic dimension based on the signification and the sense attributed to the illness, and the real dimension of its management. The investigation is pertinent to the epidemiological importance of diabetes regarding the condition of the public health in Brazil, the scarcity of researches on illnesses or chronic conditions in the Anthropology and Health area, besides the fact that it represents an opportunity to elaborate the macro and micro analytical plans in the study of the illness. The study applied the qualitative methodology through a social-anthropological perspective combining the techniques of documental research, interview, oral account and field observation (districts, households, health services) to gather the information which gave grounds for the thematic analysis. The analysis of the data on the biomedical knowledge and on the intervention models was based on basic texts on the issue, and on official normative documents about the attention given to diabetes, including the accounts of diabetics, non-diabetics and of health professionals who treat the illness. Through this ¿integrating constructivist¿ approach, to which social reality consists of interactional and interpretative practices and, also, of the participation of social structure elements; the social representations and the illness experience were articulately taken in a relation of circular influence as components of the illness onset process, making, this way, both the social and cultural determination and the individual¿s total autonomy/freedom relative. The concept of social representations is grounded in the French Sociology with the Claudine Herzlich approach, whereas the illness experience found grounds in the phenomenological support. The study concluded that the way a person suffering from diabetes thinks and deals with it involves material and symbolic factors of social context, of the day-to-day life, of the biography of the patient, of experience (current and previous, personal and of other¿s) and of the history of the disease itself. Health professionals, though imbued with the medical-scientific speech reinterpret the erudite knowledge on diabetes in their practice based on their personal and professional experience mediated by the representations. In both segments, the illness mobilizes knowledge and practices which are reciprocally redesigned in relation to the experience, to the representations mediated by the contextual elements
Doutorado
Saude Coletiva
Doutor em Saude Coletiva

Nas últimas décadas, observou-se um aumento gradativo na utilização de Veículo Aéreo Não Tripulado (VANT) em diversas áreas, entre elas, monitoramento do uso da terra, operações de busca e resgate, acompanhamento de impactos ambientais, vigilância de fronteiras, entre outras. Há expectativas no aumento do emprego de VANT em aplicações civis e militares devido ao baixo custo de desenvolvimento e operacional, quando comparados com aeronaves tripuladas. A ausência de tripulação embarcada durante o emprego de VANT, principalmente em missões de grande periculosidade, também é uma vantagem, pois diminui os riscos à vida humana. Com o aumento do emprego de VANT o desenvolvimento de sistemas para a sua navegação autônoma tem sido tema de diversas pesquisas. Uma das tarefas dos sistemas de navegação autônoma de VANT é estimar sua posição. A grande maioria dos sistemas de navegação autônoma de VANT utilizam a fusão de dados do Sistema de Navegação Inercial (INS, do inglês, Inertial Navigation System) com os dados do Sistema de Navegação Global por Satélite (Global Navigation Satellite System) (principalmente o Sistema de Posicionamento Global (GPS, do inglês, Global Positioning System)) para estimar a posição do VANT. Mas o GNSS pode sofrer interferência em seu sinal devido a ataques maliciosos e a fenômenos naturais. O desenvolvimento de um sistema de visão computacional, que utiliza imagens capturadas e processadas em tempo de voo para determinar a localização do VANT, pode substituir a informação do GNSS. Entretanto, ainda é um desafio o desenvolvimento de um sistema de estimação da posição do VANT por processamento de imagens para operar durante a navegação da aeronave sobre regiões cobertas por água (por exemplo, o oceano) e em condições de baixa ou sem luminosidade. Neste contexto, esta tese de doutorado apresenta uma metodologia que estima a posição geográfica de um VANT quando este sobrevoa regiões cobertas por água e regiões com baixa ou sem luminosidade utilizando imagens provenientes de um sensor ativo denominado Light Detection And Ranging (LiDAR). A metodologia proposta utiliza a fusão de dados, por um Filtro de Partículas Não-Extensível (FPNE), de duas técnicas de visão computacional, odometria visual e registro automático de imagens, para estimar a posição da aeronave. O sistema de estimação da posição requer que o processamento seja feito em sistemas embarcados e em tempo de voo, por este motivo, a metodologia proposta é desenvolvida em computadores portáteis e de baixo consumo e que permitam a computação de alto desempenho. Para a validação da metodologia proposta são realizados testes com dois conjunto de dados diferentes: o primeiro com dados reais do voo de VANT, mas capturado por uma câmera de vídeo; o segundo, uma simulação utilizando imagens de um sensor LiDAR. Os resultados obtidos com as técnicas empregadas mostram-se promissores para emprego na navegação autônoma de VANT em regiões cobertas por água ou e em regiões com baixa ou sem luminosidade.
In the last years, there was a gradual increase in the employment of Unmanned Aerial Vehicles (UAV) in several areas, among them, land-use monitoring, search and rescue operations, monitoring of environmental impacts, border surveillance, and others. There is an expectation that the use of UAVs will increase in the future, due to the low costs of development and low operational costs when compared to manned aircraft. The main advantage of the UAV employment is the absence of onboard crew, which reduces the risks to human life. With the increase of UAV employment, the development of systems for its autonomous navigation has been subject of several investigations. One of the tasks of autonomous navigation systems for UAV is to estimate its position. The main strategy applied for estimating the UAV position is the use of information from Inertial Navigation System (INS) combined with information from Global Navigation Satellite System (GNSS).The signal of GNSS can suffer an outage due to malicious attacks and natural phenomena. Thus, the development of a computer vision system, which uses images captured and processed in flight time, can be used to determine the UAV location and replace the information from GNSS. However, the development of a computer vision system for estimating the UAV position in a situation of flight over water-covered areas (eg the ocean) and flight in low light conditions is a challenge. In this context, this doctoral thesis presents an approach for estimating the geographical position of a UAV, when it flies over regions covered by water and regions with low light conditions. The approach uses images from an active sensor called Light Detection And Ranging (LiDAR) to allow the flight in those conditions. The proposed approach estimates the aircraft position by employing data fusion of two techniques of position estimation by computer vision: visual odometry and the image matching. The data fusion algorithm is performed by an Non-Extensible Particle Filter (NEPF). The approach requires that the processing be done in embedded systems and in flight time, thus, the proposed method is developed in portable and low-power high-performance computer. For the validation of the proposed method, two different data sets are applied: the first one composed by real flight data from an UAV, with images captured by its video camera; and the second one, a simulation using images from a LiDAR sensor. The approach results are promising for the UAV position estimation in regions covered by water or in regions with low light conditions.

A utilização de lasers de estado sólido bombeados por diodos laser tem atraído interesse crescente devido a sua alta eficiência, seu tamanho compacto e com a possibilidade da operação com altas potências-pico. O objetivo deste trabalho foi estudar configurações de cavidades ressonantes laser, que possibilitem a obtenção de pulsos chaveados Q e futura dobra de freqüência, para aplicações em LIDAR (Light Detection and Ranging), utilizando como meio ativo cristais de Nd:YLF crescidos pelo método de Czochralski no Centro de Lasers e Aplicações IPEN USP, com bombeio lateral por diodo laser, com uma, duas, quatro e nove reflexões internas totais do feixe laser na superfície do cristal. Das seis cavidades construídas, três cavidades foram desenvolvidas para operarem com baixo ganho, grande armazenamento de energia e com grande aproveitamento de inversão de população, bombeadas com diodo laser em 806 nm e outras três cavidades foram desenvolvidas para operarem com alta absorção de bombeio e alto ganho, bombeadas com diodo laser emitindo em 797 nm. Das seis cavidades desenvolvidas, as que apresentaram melhor eficiência de conversão óptica, foram as cavidades operando com alto ganho e alta absorção (cavidade quatro a seis), com 29,5% e 20,7% de eficiência de conversão óptica, propiciando a obtenção de pulsos chaveados de 20 ns com potência-pico de 160kW.
The use of diode pumped, solid state lasers has caused increasing interest due its high efficiency, compactness and possibility of operation in high peak powers. The goal of this work was the study of configurations of laser resonators that allow to obtain Q-switched pulses and a future frequency doubling, for LIDAR (Light Detection and Ranging) applications. Using as active medium Nd:YLF crystals grown by the Czochralski method at the Centro de Lasers e Aplicações IPEN USP, side pumping by laser diodes, with one, two, four and nine total internal reflexions of the laser beam at the surface of the crystals was employed. From the six resonators built, three of them were designed to work with low gain, pumped by a laser diode emitting at 806 nm. Another three laser resonators were designed to work with high pump absorption and high gain, pumped by a laser diode emitting at 797 nm. From the six developed resonators, the ones which showed the best optical conversion efficiency, were the resonators designed to work with high gain and high absorption (resonator four to six), showing 29,5% and 20,7% optical conversion efficiency, and enabling obtaining Q-switched pulses of 20 ns, with 160 kW peak power.

Mestrado em Gestão e Estratégia Industrial
Nos tempos actuais, não basta ser rentável, há que criar uma cultura de melhoria contínua de forma a garantir a sustentabilidade futura do negócio. O Projecto proposto pretende pois estudar métodos e técnicas de planeamento e controlo da produção em ambientes de incerteza numa indústria conserveira de atum, de modo a maximizar o cumprimento do plano de produção e optimizar os recursos disponíveis. Deste modo integraram-se algumas incertezas no MRP II existente, e adoptaram-se algumas das técnicas e metodologias 6-Sigma, visando introduzir conceitos de lean manufacturing. Constatou-se que as soluções optadas permitiram alcançar o desiderato pretendido. Por fim, refira-se que o sucesso deste projecto deveu-se antes de mais à equipa do Pico e do Faial, cujo desempenho superou as expectativas.

In forestry it is important to have accurate information about the forest. LiDAR (laser scanning) can be used to scan vast areas of forest and from the data extract information about the trees. The purpose of this thesis is to develop a simulator for LiDAR data. The simulator will be tested on a method for tree localization (Holmgren and Lindberg 2013) to see how parameters like tree density and laser frequency effects the accuracy of the localization. First a simulator which uses simple shaped trees (in the shape of cones) is written. Later on a tree model based on real laser data is created by the use of histogram density estimation. Ray-tracing is used to simulate the LiDAR data which the trees give rise to. This is done by following each ray of laser and see where it is reflected. The tree localization method is tested on the data and we report the following findings: 1: The percentage of correctly located trees decreases with increasing tree density. 2: Larger trees yields an increase in false trees found by the localization method. 3: Higher laser pulse density decreases the number of false trees. 4: The minimum radius at which the localization method start fitting ellipsoids greatly effects the number of false trees. Smaller radius yield more false trees.

The mining industry is currently facing a transition from manually operated vehicles to remote or semi-automated vehicles. The vision is fully autonomous vehicles being part of a larger fleet, with humans only setting high-level goals for the autonomous fleet to execute in an optimal way. An enabler for this vision is the presence of robust, reliable and highly accurate localization. This is a requirement for having areas in a mine with mixed autonomous vehicles, manually operated vehicles, and unprotected personnel. The robustness of the system is important from a safety as well as a productivity perspective. When every vehicle in the fleet is connected, an uncertain position of one vehicle can result in the whole fleet begin halted for safety reasons. Providing reliable positions is not trivial in underground mine environments, where access to global satellite based navigation systems is denied. Due to the harsh and dynamically changing environment, onboard positioning solutions are preferred over systems utilizing external infrastructure. The focus of this thesis is localization systems relying only on sensors mounted on the vehicle, e.g., odometers, inertial measurement units, and 2D LIDAR sensors. The localization methods are based on the Bayesian filtering framework and estimate the distribution of the position in the reference frame of a predefined map covering the operation area. This thesis presents research where the properties of 2D LIDAR data, and specifically characteristics when obtained in an underground mine, are considered to produce position estimates that are robust, reliable, and accurate. First, guidelines are provided for how to tune the design parameters associated with the unscented Kalman filter (UKF). The UKF is an algorithm designed for nonlinear dynamical systems, applicable to this particular positioning problem. There exists no general guidelines for how to choose the parameter values, and using the standard values suggested in the literature result in unreliable estimates in the considered application. Results show that a proper parameter setup substantially improves the performance of this algorithm. Next, strategies are developed to use only a subset of available measurements without losing quality in the position estimates. LIDAR sensors typically produce large amounts of data, and demanding real-time positioning information limits how much data the system can process. By analyzing the information contribution from each individual laser ray in a complete LIDAR scan, a subset is selected by maximizing the information content. It is shown how 80% of available LIDAR measurements can be dropped without significant loss of accuracy. Last, the problem of robustness in non-static environments is addressed. By extracting features from the LIDAR data, a computationally tractable localization method, resilient to errors in the map, is obtained. Moving objects, and tunnels being extended or closed, result in a map not corresponding to the LIDAR observations. State-of-the-art feature extraction methods for 2D LIDAR data are identified, and a localization algorithm is defined where features found in LIDAR data are matched to features extracted from the map. Experiments show that regions of the map containing errors are automatically ignored since no matching features are found in the LIDAR data, resulting in more robust position estimates.

Additional funding agency: Epiroc Rock Drills AB

Vernier Tuned Distributed Bragg Reflector (VT-DBR) lasers have had great success in the field of Swept-Source Optical Coherence Tomography (SS-OCT) due to their continuous and nearly 40 nm wavelength tuning range in a single longitudinal mode. Fast sweeps allow for real time imaging with micrometer resolution at a distance of a few centimeters. While this laser has proven quite useful as a medical imaging tool via OCT, it has yet to similarly prove itself for general light detection and ranging (LIDAR) applications due to range limitations that arise from a finite laser coherence length. The goal of this thesis is to explore LIDAR applications for VT-DBR lasers and how to improve VT-DBR performance for LIDAR. In the scope of this work, LIDAR is laser imaging at tens or hundreds of meters with a resolution finer than 10cm. In order to achieve this kind of LIDAR performance with a VT-DBR laser, the laser must have a linewidth less than 1MHz over a tuning range of around 10GHz. This thesis outlines two methods towards this goal. The bulk of this work is dedicated to looking for and characterizing VT-DBR tuning paths with fundamentally narrow linewidth using microampere currents in both forward and reverse bias conditions. The second part of this thesis is a preliminary design of an optical frequency-locked loop to reduce laser phase noise, which subsequently reduces the laser linewidth. By tuning with small currents in the forward bias condition, nearly the entire range of laser wavelengths could be tuned to, but areas of narrow linewidth were both sparse and very sensitive to any change in bias. The reverse bias case showed limited but continuous tuning with increased reverse current magnitude. In this reverse biased photo-detector mode the laser exhibited narrower linewidth less than 15MHz, with the linewidth at intrinsically narrow levels when all three sections reverse biased. Also promising was a subset of reverse bias conditions that only used a variable resistance across a laser section with no externally applied bias. This resistance tuning method gave a tuning range of more than 7GHz while maintaining an intrinsically narrow linewidth. The optical frequency-locked loop was able to achieve DC frequency locking but unable to reduce laser linewidth. More work needs to be done to achieve enough phase noise reduction to see an appreciable reduction in linewidth.