Zeitschriftenartikel: „Handheld laser scanning“

1

DuBose, Theodore, Derek Nankivil, Francesco LaRocca, Gar Waterman, Kristen Hagan, James Polans, Brenton Keller et al. „Handheld adaptive optics scanning laser ophthalmoscope“. Optica 5, Nr. 9 (23.08.2018): 1027. http://dx.doi.org/10.1364/optica.5.001027.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

2

Hagan, Kristen, Theodore DuBose, David Cunefare, Gar Waterman, Jongwan Park, Corey Simmerer, Anthony N. Kuo, Ryan P. McNabb, Joseph A. Izatt und Sina Farsiu. „Multimodal handheld adaptive optics scanning laser ophthalmoscope“. Optics Letters 45, Nr. 17 (01.09.2020): 4940. http://dx.doi.org/10.1364/ol.402392.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

3

Komissarov, A. V., A. V. Remizov, M. M. Shlyakhova und K. K. Yambaev. „Handheld Laser Scanner Research“. Geodesy and Cartography 952, Nr. 10 (20.11.2019): 47–54. http://dx.doi.org/10.22389/0016-7126-2019-952-10-47-54.

Der volle Inhalt der Quelle

Annotation:

The authors consider hand-held laser scanners, as a new photogrammetric tool for obtaining three-dimensional models of objects. The principle of their work and the newest optical systems based on various sensors measuring the depth of space are described in detail. The method of simultaneous navigation and mapping (SLAM) used for combining single scans into point cloud is outlined. The formulated tasks and methods for performing studies of the DotProduct (USA) hand-held laser scanner DPI?8X based on a test site survey are presented. The accuracy requirements for determining the coordinates of polygon points are given. The essence of the performed experimental research of the DPI?8X scanner is described, including scanning of a test object at various scanner distances, shooting a test polygon from various scanner positions and building point cloud, repeatedly shooting the same area of the polygon to check the stability of the scanner. The data on the assessment of accuracy and analysis of research results are given. Fields of applying hand-held laser scanners, their advantages and disadvantages are identified.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

4

Bleier, M., und A. Nüchter. „TOWARDS ROBUST SELF-CALIBRATION FOR HANDHELD 3D LINE LASER SCANNING“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W8 (13.11.2017): 31–36. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w8-31-2017.

Der volle Inhalt der Quelle

Annotation:

This paper studies self-calibration of a structured light system, which reconstructs 3D information using video from a static consumer camera and a handheld cross line laser projector. Intersections between the individual laser curves and geometric constraints on the relative position of the laser planes are exploited to achieve dense 3D reconstruction. This is possible without any prior knowledge of the movement of the projector. However, inaccurrately extracted laser lines introduce noise in the detected intersection positions and therefore distort the reconstruction result. Furthermore, when scanning objects with specular reflections, such as glossy painted or metalic surfaces, the reflections are often extracted from the camera image as erroneous laser curves. In this paper we investiagte how robust estimates of the parameters of the laser planes can be obtained despite of noisy detections.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

5

Sadeghi, F., H. Arefi, A. Fallah und M. Hahn. „3D BUILDING FAÇADE RECONSTRUCTION USING HANDHELD LASER SCANNING DATA“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1-W5 (11.12.2015): 625–30. http://dx.doi.org/10.5194/isprsarchives-xl-1-w5-625-2015.

Der volle Inhalt der Quelle

Annotation:

3D The three dimensional building modelling has been an interesting topic of research for decades and it seems that photogrammetry methods provide the only economic means to acquire truly 3D city data. According to the enormous developments of 3D building reconstruction with several applications such as navigation system, location based services and urban planning, the need to consider the semantic features (such as windows and doors) becomes more essential than ever, and therefore, a 3D model of buildings as block is not any more sufficient. To reconstruct the façade elements completely, we employed the high density point cloud data that obtained from the handheld laser scanner. The advantage of the handheld laser scanner with capability of direct acquisition of very dense 3D point clouds is that there is no need to derive three dimensional data from multi images using structure from motion techniques. This paper presents a grammar-based algorithm for façade reconstruction using handheld laser scanner data. The proposed method is a combination of bottom-up (data driven) and top-down (model driven) methods in which, at first the façade basic elements are extracted in a bottom-up way and then they are served as pre-knowledge for further processing to complete models especially in occluded and incomplete areas. The first step of data driven modelling is using the conditional RANSAC (RANdom SAmple Consensus) algorithm to detect façade plane in point cloud data and remove noisy objects like trees, pedestrians, traffic signs and poles. Then, the façade planes are divided into three depth layers to detect protrusion, indentation and wall points using density histogram. Due to an inappropriate reflection of laser beams from glasses, the windows appear like holes in point cloud data and therefore, can be distinguished and extracted easily from point cloud comparing to the other façade elements. Next step, is rasterizing the indentation layer that holds the windows and doors information. After rasterization process, the morphological operators are applied in order to remove small irrelevant objects. Next, the horizontal splitting lines are employed to determine floors and vertical splitting lines are employed to detect walls, windows, and doors. The windows, doors and walls elements which are named as terminals are clustered during classification process. Each terminal contains a special property as width. Among terminals, windows and doors are named the geometry tiles in definition of the vocabularies of grammar rules. Higher order structures that inferred by grouping the tiles resulted in the production rules. The rules with three dimensional modelled façade elements constitute formal grammar that is named façade grammar. This grammar holds all the information that is necessary to reconstruct façades in the style of the given building. Thus, it can be used to improve and complete façade reconstruction in areas with no or limited sensor data. Finally, a 3D reconstructed façade model is generated that the accuracy of its geometry size and geometry position depends on the density of the raw point cloud.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

6

LaRocca, Francesco, Derek Nankivil, Sina Farsiu und Joseph A. Izatt. „Handheld simultaneous scanning laser ophthalmoscopy and optical coherence tomography system“. Biomedical Optics Express 4, Nr. 11 (01.10.2013): 2307. http://dx.doi.org/10.1364/boe.4.002307.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

7

Yıldırım, I. D., B. Sarioglu und Y. D. Gokdel. „3D Printed Head for a Handheld Laser Scanning Confocal Microscope“. Instruments and Experimental Techniques 64, Nr. 2 (März 2021): 301–7. http://dx.doi.org/10.1134/s0020441221010176.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

8

Patil, Chetan A., Christopher L. Arrasmith, Mark A. Mackanos, David L. Dickensheets und Anita Mahadevan-Jansen. „A handheld laser scanning confocal reflectance imaging–confocal Raman microspectroscopy system“. Biomedical Optics Express 3, Nr. 3 (09.02.2012): 488. http://dx.doi.org/10.1364/boe.3.000488.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

9

LaRocca, Francesco, Derek Nankivil, Sina Farsiu und Joseph A. Izatt. „True color scanning laser ophthalmoscopy and optical coherence tomography handheld probe“. Biomedical Optics Express 5, Nr. 9 (27.08.2014): 3204. http://dx.doi.org/10.1364/boe.5.003204.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

10

Wang, Xiaomin, Zexiao Xie, Kun Wang und Liqin Zhou. „Research on a Handheld 3D Laser Scanning System for Measuring Large-Sized Objects“. Sensors 18, Nr. 10 (21.10.2018): 3567. http://dx.doi.org/10.3390/s18103567.

Der volle Inhalt der Quelle

Annotation:

A handheld 3D laser scanning system is proposed for measuring large-sized objects on site. This system is mainly composed of two CCD cameras and a line laser projector, in which the two CCD cameras constitute a binocular stereo vision system to locate the scanner’s position in the fixed workpiece coordinate system online, meanwhile the left CCD camera and the laser line projector constitute a structured light system to get the laser lines modulated by the workpiece features. The marked points and laser line are both obtained in the coordinate system of the left camera in each moment. To get the workpiece outline, the handheld scanner’s position is evaluated online by matching up the marked points got by the binocular stereo vision system and those in the workpiece coordinate system measured by a TRITOP system beforehand; then the laser line with workpiece’s features got at this moment is transformed into the fixed workpiece coordinate system. Finally, the 3D information composed by the laser lines can be reconstructed in the workpiece coordinate system. A ball arm with two standard balls, which is placed on a glass plate with many marked points randomly stuck on, is measured to test the system accuracy. The distance errors between the two balls are within ±0.05 mm, the radius errors of the two balls are all within ±0.04 mm, the distance errors from the scatter points to the fitted sphere are distributed evenly, within ±0.25 mm, without accumulated errors. Measurement results of two typical workpieces show that the system can measure large-sized objects completely with acceptable accuracy and have the advantage of avoiding some deficiencies, such as sheltering and limited measuring range.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

11

Gollob, Christoph, Tim Ritter und Arne Nothdurft. „Comparison of 3D Point Clouds Obtained by Terrestrial Laser Scanning and Personal Laser Scanning on Forest Inventory Sample Plots“. Data 5, Nr. 4 (31.10.2020): 103. http://dx.doi.org/10.3390/data5040103.

Der volle Inhalt der Quelle

Annotation:

In forest inventory, trees are usually measured using handheld instruments; among the most relevant are calipers, inclinometers, ultrasonic devices, and laser range finders. Traditional forest inventory has been redesigned since modern laser scanner technology became available. Laser scanners generate massive data in the form of 3D point clouds. We have developed a novel methodology to provide estimates of the tree positions, stem diameters, and tree heights from these 3D point clouds. This dataset was made publicly accessible to test new software routines for the automatic measurement of forest trees using laser scanner data. Benchmark studies with performance tests of different algorithms are welcome. The dataset contains co-registered raw 3D point-cloud data collected on 20 forest inventory sample plots in Austria. The data were collected by two different laser scanning systems: (1) A mobile personal laser scanner (PLS) (ZEB Horizon, GeoSLAM Ltd., Nottingham, UK) and (2) a static terrestrial laser scanner (TLS) (Focus3D X330, Faro Technologies Inc., Lake Mary, FL, USA). The data also contain digital terrain models (DTMs), field measurements as reference data (ground-truth), and the output of recent software routines for the automatic tree detection and the automatic stem diameter measurement.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

12

Kumar, Karthik, Rony Avritscher, Youmin Wang, Nancy Lane, David C. Madoff, Tse-Kuan Yu, Jonathan W. Uhr und Xiaojing Zhang. „Handheld histology-equivalent sectioning laser-scanning confocal optical microscope for interventional imaging“. Biomedical Microdevices 12, Nr. 2 (10.12.2009): 223–33. http://dx.doi.org/10.1007/s10544-009-9377-6.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

13

GRIVET, D., M. ESPINASSE, E. CINOTTI, B. LABEILLE, F. CAMBAZARD, JL PERROT, N. CAMPOLMI et al. „In vivo laser scanning microscopy of cornea, conjunctiva and ocular adnexa with a handheld dermatological laser-scanning microscope: new perspectives“. Acta Ophthalmologica 90 (06.08.2012): 0. http://dx.doi.org/10.1111/j.1755-3768.2012.4642.x.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

14

Wang, Xing Xing, Jin Dong Wei, Yi Pei, Yu Zhu und Hong Jun Ni. „Modeling Design and Rapid Prototyping Manufacture of Cream Bottle Based on Handheld Laser Scanning“. Applied Mechanics and Materials 752-753 (April 2015): 1301–6. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.1301.

Der volle Inhalt der Quelle

Annotation:

Reverse Engineering (RE) and Rapid Prototyping (RP) were used for manufacturing cream bottle. Points cloud data of cream bottle was accessed by handheld laser scanner firstly. Then, points cloud data was handed by Imageware software and the three-dimensional model was formed by Solidworks software. Finally, the entity model was manufacturing by RP machine. In the research, rapid prototyping was combined with reverse engineering technology, manufacturing cycle was shorten, production requirements, improve efficiency and other advantages were met.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

15

Kelly, John P. „Imaging a Child's Fundus Without Dilation Using a Handheld Confocal Scanning Laser Ophthalmoscope“. Archives of Ophthalmology 121, Nr. 3 (01.03.2003): 391. http://dx.doi.org/10.1001/archopht.121.3.391.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

16

VATANDAŞLAR, Can, und Mustafa ZEYBEK. „Application of handheld laser scanning technology for forest inventory purposes in the NE Turkey“. TURKISH JOURNAL OF AGRICULTURE AND FORESTRY 44, Nr. 3 (01.06.2020): 229–42. http://dx.doi.org/10.3906/tar-1903-40.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

17

Jurjević, Luka, Mateo Gašparović, Xinlian Liang und Ivan Balenović. „Assessment of Close-Range Remote Sensing Methods for DTM Estimation in a Lowland Deciduous Forest“. Remote Sensing 13, Nr. 11 (24.05.2021): 2063. http://dx.doi.org/10.3390/rs13112063.

Der volle Inhalt der Quelle

Annotation:

Digital terrain models (DTMs) are important for a variety of applications in geosciences as a valuable information source in forest management planning, forest inventory, hydrology, etc. Despite their value, a DTM in a forest area is typically lower quality due to inaccessibility and limited data sources that can be used in the forest environment. In this paper, we assessed the accuracy of close-range remote sensing techniques for DTM data collection. In total, four data sources were examined, i.e., handheld personal laser scanning (PLShh, GeoSLAM Horizon), terrestrial laser scanning (TLS, FARO S70), unmanned aerial vehicle (UAV) photogrammetry (UAVimage), and UAV laser scanning (ULS, LS Nano M8). Data were collected within six sample plots located in a lowland pedunculate oak forest. The reference data were of the highest quality available, i.e., total station measurements. After normality and outliers testing, both robust and non-robust statistics were calculated for all close-range remote sensing data sources. The results indicate that close-range remote sensing techniques are capable of achieving higher accuracy (root mean square error < 15 cm; normalized median absolute deviation < 10 cm) than airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) data that are generally understood to be the best data sources for DTM on a large scale.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

18

Maset, E., S. Cucchiaro, F. Cazorzi, F. Crosilla, A. Fusiello und A. Beinat. „INVESTIGATING THE PERFORMANCE OF A HANDHELD MOBILE MAPPING SYSTEM IN DIFFERENT OUTDOOR SCENARIOS“. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B1-2021 (28.06.2021): 103–9. http://dx.doi.org/10.5194/isprs-archives-xliii-b1-2021-103-2021.

Der volle Inhalt der Quelle

Annotation:

Abstract. In recent years, portable Mobile Mapping Systems (MMSs) are emerging as valuable survey instruments for fast and efficient mapping of both internal and external environments. The aim of this work is to assess the performance of a commercial handheld MMS, Gexcel HERON Lite, in two different outdoor applications. The first is the mapping of a large building, which represents a standard use-case scenario of this technology. Through the second case study, that consists in the survey of a torrent reach, we investigate instead the applicability of the handheld MMS for natural environment monitoring, a field in which portable systems are not yet widely employed. Quantitative and qualitative assessment is presented, comparing the point clouds obtained from the HERON Lite system against reference models provided by traditional techniques (i.e., Terrestrial Laser Scanning and Photogrammetry).

APA, Harvard, Vancouver, ISO und andere Zitierweisen

19

Vasilakos, C., S. Chatzistamatis, O. Roussou und N. Soulakellis. „TERRESTRIAL PHOTOGRAMMETRY VS LASER SCANNING FOR RAPID EARTHQUAKE DAMAGE ASSESSMENT“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W4 (06.03.2018): 527–33. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w4-527-2018.

Der volle Inhalt der Quelle

Annotation:

Abstract. Building damage assessment caused by earthquakes is essential during the response phase following a catastrophic event. Modern techniques include terrestrial and aerial photogrammetry based on Structure from Motion algorithm and Laser Scanning with the latter to prove its superiority in accuracy assessment due to the high-density point clouds. However, standardized procedures during emergency surveys often could not be followed due to restrictions of outdoor operations because of debris or decrepit buildings, the high human presence of civil protection agencies, expedited deployment of survey team and cost of operations. The aim of this paper is to evaluate whether terrestrial photogrammetry based on a handheld amateur DSLR camera can be used to map building damages, structural deformations and facade production in an accepted accuracy comparing to laser scanning technique. The study area is the Vrisa village, Lesvos, Greece where a Mw&thinsp;6.3 earthquake occurred on June 12th, 2017. A dense point cloud from some digital images created based on Structure from Motion algorithm and compared with a dense point cloud acquired by a laser scanner. The distance measurement and the comparison were conducted with the Multiscale Model to Model Cloud Comparison method. According to the results, the mean of the absolute distances between the two clouds is 0.038&thinsp;m while the 94.9&thinsp;% of the point distances are less than 0.1&thinsp;m. Terrestrial photogrammetry proved to be an accurate methodology for rapid earthquake damage assessment thus its products were used by local authorities for the calculation of the compensation for the property loss.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

20

Hyyppä, Eric, Xiaowei Yu, Harri Kaartinen, Teemu Hakala, Antero Kukko, Mikko Vastaranta und Juha Hyyppä. „Comparison of Backpack, Handheld, Under-Canopy UAV, and Above-Canopy UAV Laser Scanning for Field Reference Data Collection in Boreal Forests“. Remote Sensing 12, Nr. 20 (13.10.2020): 3327. http://dx.doi.org/10.3390/rs12203327.

Der volle Inhalt der Quelle

Annotation:

In this work, we compared six emerging mobile laser scanning (MLS) technologies for field reference data collection at the individual tree level in boreal forest conditions. The systems under study were an in-house developed AKHKA-R3 backpack laser scanner, a handheld Zeb-Horizon laser scanner, an under-canopy UAV (Unmanned Aircraft Vehicle) laser scanning system, and three above-canopy UAV laser scanning systems providing point clouds with varying point densities. To assess the performance of the methods for automated measurements of diameter at breast height (DBH), stem curve, tree height and stem volume, we utilized all of the six systems to collect point cloud data on two 32 m-by-32 m test sites classified as sparse (n = 42 trees) and obstructed (n = 43 trees). To analyze the data collected with the two ground-based MLS systems and the under-canopy UAV system, we used a workflow based on our recent work featuring simultaneous localization and mapping (SLAM) technology, a stem arc detection algorithm, and an iterative arc matching algorithm. This workflow enabled us to obtain accurate stem diameter estimates from the point cloud data despite a small but relevant time-dependent drift in the SLAM-corrected trajectory of the scanner. We found out that the ground-based MLS systems and the under-canopy UAV system could be used to measure the stem diameter (DBH) with a root mean square error (RMSE) of 2–8%, whereas the stem curve measurements had an RMSE of 2–15% that depended on the system and the measurement height. Furthermore, the backpack and handheld scanners could be employed for sufficiently accurate tree height measurements (RMSE = 2–10%) in order to estimate the stem volumes of individual trees with an RMSE of approximately 10%. A similar accuracy was obtained when combining stem curves estimated with the under-canopy UAV system and tree heights extracted with an above-canopy flying laser scanning unit. Importantly, the volume estimation error of these three MLS systems was found to be of the same level as the error corresponding to manual field measurements on the two test sites. To analyze point cloud data collected with the three above-canopy flying UAV systems, we used a random forest model trained on field reference data collected from nearby plots. Using the random forest model, we were able to estimate the DBH of individual trees with an RMSE of 10–20%, the tree height with an RMSE of 2–8%, and the stem volume with an RMSE of 20–50%. Our results indicate that ground-based and under-canopy MLS systems provide a promising approach for field reference data collection at the individual tree level, whereas the accuracy of above-canopy UAV laser scanning systems is not yet sufficient for predicting stem attributes of individual trees for field reference data with a high accuracy.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

21

Vatandaşlar, Can, und Mustafa Zeybek. „Extraction of forest inventory parameters using handheld mobile laser scanning: A case study from Trabzon, Turkey“. Measurement 177 (Juni 2021): 109328. http://dx.doi.org/10.1016/j.measurement.2021.109328.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

22

Ahmed, Mahmoud, C. T. Haas und Ralph Haas. „Using digital photogrammetry for pipe-works progress tracking1This paper is one of a selection of papers in this Special Issue on Construction Engineering and Management.“ Canadian Journal of Civil Engineering 39, Nr. 9 (September 2012): 1062–71. http://dx.doi.org/10.1139/l2012-055.

Der volle Inhalt der Quelle

Annotation:

Pipe-works are among the most complicated items to be tracked in the course of monitoring construction project progress. Traditionally, the tracking of pipe-works progress is conducted either manually or using laser scanning technology. While laser scanning is a 3D imaging technique, and commercial software exists to construct 3D CAD models of piping based on such images, it suffers from portability, purchase cost, and other disadvantages. This paper describes digital photogrammetry technology as an alternative for pipe-works reconstruction and as a cost effective tracking tool. For validation, data was collected using a handheld digital camera to acquire images inside a new building under construction. Progress of the pipe-work networks of different types and sizes in the new building was monitored during the construction phases. In addition to the known accuracy and robustness of photogrammetry, it was found that the use of digital photogrammetry provided a practical and low-cost approach.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

23

Ryan, Robert W., Tamir Wolf, Robert F. Spetzler, Stephen W. Coons, Yoel Fink und Mark C. Preul. „Application of a flexible CO2 laser fiber for neurosurgery: laser-tissue interactions“. Journal of Neurosurgery 112, Nr. 2 (Februar 2010): 434–43. http://dx.doi.org/10.3171/2009.7.jns09356.

Der volle Inhalt der Quelle

Annotation:

Object The CO2 laser has an excellent profile for use in neurosurgery. Its high absorption in water results in low thermal spread, sparing adjacent tissue. Use of this laser has been limited to line-of-sight applications because no solid fiber optic cables could transmit its wavelength. Flexible photonic bandgap fiber technology enables delivery of CO2 laser energy through a flexible fiber easily manipulated in a handheld device. The authors examined and compared the first use of this CO2 laser fiber to conventional methods for incising neural tissue. Methods Carbon dioxide laser energy was delivered in pulsed or continuous wave settings for different power settings, exposure times, and distances to cortical tissue of 6 anesthetized swine. Effects of CO2 energy on the tissue were compared with bipolar cautery using a standard pial incision technique, and with scalpel incisions without cautery. Tissue was processed for histological analysis (using H & E, silver staining, and glial fibrillary acidic protein immunohistochemistry) and scanning electron microscopy, and lesion measurements were made. Results Light microscopy and scanning electron microscopy revealed laser incisions of consistent shape, with central craters surrounded by limited zones of desiccated and edematous tissue. Increased laser power resulted in deeper but not significantly wider incisions. Bipolar cautery lesions showed desiccated and edematous zones but did not incise the pia, and width increased more than depth with higher power. Incisions made without using cautery produced hemorrhage but minimal adjacent tissue damage. Conclusions The photonic bandgap fiber CO2 laser produced reliable cortical incisions, adjustable over a range of settings, with minimal adjacent thermal tissue damage. Ease of application under the microscope suggests this laser system has reached true practicality for neurosurgery.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

24

Sadeghi, F., und H. Arefi. „OCCLUDED AREA REMOVING FROM HANDHELD LASER SCANNER DATA DURING 3D BUILDING MODELLING“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W18 (19.10.2019): 935–39. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w18-935-2019.

Der volle Inhalt der Quelle

Annotation:

Abstract. 3D building modelling has been turned to be one of the most interesting and hottest subjects in photogrammetry in last two decades, and it seems that photogrammetry provides the only economic means to acquire truly 3D city-data. Most of the researches proposed methods for 3d building modelling in LoD2 using aerial images and LIDAR data and the produced models will be enriched by oblique images, therefore there is always a demand for a user to interpret the façade or in other manual building reconstruction process the operator should draw boundaries to represent the building model and the process will be too time-consuming for 3d modelling for a whole city. Creating building facade models for a whole city requires considerable work, therefore for decades, much research has been dedicated to the automation of this reconstruction process. Nowadays researchers attempt to recommend a new method which is flexible to model hug variety of buildings and has a solution for several challenges such as irrelevant objects (pedestrians, trees, traffic signs, etc.), occluded areas and non-homogenous data. Based on various 3d building models applications, namely navigation systems, location-based system, city planning and etc. the demand for adding semantic features (such as windows and doors) is increasing and becoming more essential, therefore simple blocks as the representation of 3d buildings aren’t sufficient anymore. Therefore 2.5 models which show the façade details using pixel values have been substituted by LoD3 models recently.The lack of automation in image based approaches can be explained by the difficulties in image interpretation. Specifically, factors like illumination and occlusion can cause considerable confusion for machine understanding and some conditions (relative orientation, feature matching, etc.) need to be accurately determined to transfer image pixels to 3D coordinates. In recent years, terrestrial laser scanning data has been proven as a valuable source for building facade reconstruction. The point density of stationary laser scanning in urban areas can be up to hundreds or thousands of points per square meter, which is high enough for documenting most details on building facades. In comparison with image-based modelling, several steps such as image matching, intersection and resection will be eliminated, while there is no need to image interpret in laser data-based reconstruction approaches, these methods face major challenges such as extracting meaningful structures from a huge amount of data.This paper presents a data-driven algorithm for façade reconstruction, using a handheld laser scanner, Zebedee. The mentioned device is consisting of 2d laser scanner and an inertial measurement unit mounted on one or two springs, it has 270-degree field of view. Its mass is 210 g which makes it ideal for low measurement and it is maximum range is 30 m. The proposed method was implemented by using the Zebedee point cloud in order to determine the challenges of zeb1 data and ensure that the introduced device can be practical for 3d reconstruction.Due to obstacle existence, operator gross errors while data capturing and façade elements arrangement, there will always be occluded area and shadows in produced data. Occluded area cause tribulation in machine understanding and problems for automatic reconstruction algorithms. The proposed method represents a new way to detect occluded area and remove the artificial objects which are produced by them. The 3d point cloud is used to cover all façade elements and details, also image matching and producing 3-dimensional data steps will be omitted from the process.The proposed workflow is indicated in figure 1. Most researches such as road, building or other objects detection and reconstruction put ground points detection in priority in order to decrease data volume and processing time, so as a pre-processing step, point cloud is classified into two separate groups (non-ground and ground points).

APA, Harvard, Vancouver, ISO und andere Zitierweisen

25

Giammanco, Ian M., Benjamin R. Maiden, Heather E. Estes und Tanya M. Brown-Giammanco. „Using 3D Laser Scanning Technology to Create Digital Models of Hailstones“. Bulletin of the American Meteorological Society 98, Nr. 7 (01.07.2017): 1341–47. http://dx.doi.org/10.1175/bams-d-15-00314.1.

Der volle Inhalt der Quelle

Annotation:

Abstract The emergence of 3D scanning technologies has provided a new opportunity to explore the shape characteristics of hailstones in great detail. The ability to effectively map the shape of hailstones will improve assessments of hailstone aerodynamic properties, how their density relates to their strength, and how radar energy is scattered. Ultimately, 3D scanning of hailstones will contribute toward research in hail detection, forecasting, and damage mitigation of severe hail, which accounts for well over $1 billion in annual insured losses. The use of a handheld 3D laser scanner in a field setting was explored during field campaigns in 2015 and 2016. Hailstones were collected following thunderstorm passages and were measured, weighed, and scanned. The system was successful in capturing 3D models of more than 40 hailstones. A full scan takes approximately 3 minutes to complete, and data can be captured at a resolution of 0.008 cm. It is believed this is the first time such a system has been used to produce 3D digital hailstone models. Analysis of the model data has shown that hailstones depart from spherical shapes as they increase in diameter, and that bulk density and strength show little correlation. While the dataset presented here is small, the use of 3D scanners in the field is a practical method to obtain detailed datasets on hailstone characteristics. In addition, these data could be used to 3D-print hailstones to explore their aerodynamics, to produce cavity molds for ice impact tests, and for modeling radar scattering properties of natural hailstone shapes.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

26

Ghahremani, Kasra, Mahdi Safa, Jamie Yeung, Scott Walbridge, Carl Haas und Sebastien Dubois. „Quality assurance for high-frequency mechanical impact (HFMI) treatment of welds using handheld 3D laser scanning technology“. Welding in the World 59, Nr. 3 (10.12.2014): 391–400. http://dx.doi.org/10.1007/s40194-014-0210-3.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

27

Lin, Wenshu, Weiwei Fan, Haoran Liu, Yongsheng Xu und Jinzhuo Wu. „Classification of Handheld Laser Scanning Tree Point Cloud Based on Different KNN Algorithms and Random Forest Algorithm“. Forests 12, Nr. 3 (03.03.2021): 292. http://dx.doi.org/10.3390/f12030292.

Der volle Inhalt der Quelle

Annotation:

Handheld mobile laser scanning (HMLS) can quickly acquire point cloud data, and has the potential to conduct forest inventory at the plot scale. Considering the problems associated with HMLS data such as large discreteness and difficulty in classification, different classification models were compared in order to realize efficient separation of stem, branch and leaf points from HMLS data. First, the HMLS point cloud was normalized and ground points were removed, then the neighboring points were identified according to three KNN algorithms and eight geometric features were constructed. On this basis, the random forest classifier was used to calculate feature importance and perform dataset training. Finally, the classification accuracy of different KNN algorithms-based models was evaluated. Results showed that the training sample classification accuracy based on the adaptive radius KNN algorithm was the highest (0.9659) among the three KNN algorithms, but its feature calculation time was also longer; The validation accuracy of two test sets was 0.9596 and 0.9201, respectively, which is acceptable, and the misclassification mainly occurred in the branch junction of the canopy. Therefore, the optimal classification model can effectively achieve the classification of stem, branch and leaf points from HMLS point cloud under the premise of comprehensive training.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

28

Camarretta, Nicolò, Peter A. Harrison, Arko Lucieer, Brad M. Potts, Neil Davidson und Mark Hunt. „Handheld Laser Scanning Detects Spatiotemporal Differences in the Development of Structural Traits among Species in Restoration Plantings“. Remote Sensing 13, Nr. 9 (28.04.2021): 1706. http://dx.doi.org/10.3390/rs13091706.

Der volle Inhalt der Quelle

Annotation:

A major challenge in ecological restoration is assessing the success of restoration plantings in producing habitats that provide the desired ecosystem functions and services. Forest structural complexity and biomass accumulation are key measures used to monitor restoration success and are important factors determining animal habitat availability and carbon sequestration. Monitoring their development through time using traditional field measurements can be costly and impractical, particularly at the landscape-scale, which is a common requirement in ecological restoration. We explored the application of proximal sensing technology as an alternative to traditional field surveys to capture the development of key forest structural traits in a restoration planting in the Midlands of Tasmania, Australia. We report the use of a hand-held laser scanner (ZEB1) to measure annual changes in structural traits at the tree-level, in a mixed species common-garden experiment from seven- to nine-years after planting. Using very dense point clouds, we derived estimates of multiple structural traits, including above ground biomass, tree height, stem diameter, crown dimensions, and crown properties. We detected annual increases in most LiDAR-derived traits, with individual crowns becoming increasingly interconnected. Time by species interaction were detected, and were associated with differences in productivity between species. We show the potential for remote sensing technology to monitor temporal changes in forest structural traits, as well as to provide base-line measures from which to assess the restoration trajectory towards a desired state.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

29

Russhakim, N. A. S., M. F. M. Ariff, N. Darwin, Z. Majid, K. M. Idris, M. A. Abbas, N. K. Zainuddin und A. R. Yusoff. „THE SUITABILITY OF TERRESTRIAL LASER SCANNING FOR STRATA BUILDING“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W9 (26.10.2018): 67–76. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w9-67-2018.

Der volle Inhalt der Quelle

Annotation:

Abstract. During the recent years, the used of terrestrial laser scanning (TLS) is becoming rapidly popular because of its ability in several applications, especially the ability to observe complex documentation of complex building and observe millions of point cloud in three-dimensional in a short period. Users of strata plan usually find it difficult to translate the traditional two-dimensional (2D) data on maps they see on a flat piece of paper to three-dimensional (3D). The TLS is able to record thousands of point clouds which contains very rich of geometry details and made the processing usually takes longer time. In addition, the demand of strata survey work has made the surveyors need to obtain the data with full of accuracy and time saves. Therefore, the aim of this study is to study the limitation uses of TLS and its suitability for strata building survey. In this study, the efficiency of TLS Leica C10 for strata building survey was determined in term of its accuracy and comparing with Zeb-Revo Handheld Mobile Laser Scanning (MLS) and the distometer. The accuracy for scanned data from both, TLS and MLS were compared with the Distometer by using root mean square error (RMSE) formula. Then, the 3D model of the building for both data, TLS and MLS were produced to analyze the visualization for different type of scanners. The software used; Autodesk Recap, Autodesk Revit, Leica Cyclone Software, Autocad Software and Geo Slam Software. The RMSE for TLS technique is 0.001m meanwhile, RMSE for MLS technique is 0.007m. The difference between these two techniques is 0.006m. The 3D model of building for both models did not have too much different but the scanned data from TLS is much easier to process and generate the 3D model compared to scanned data from MLS. It is because the scanned data from TLS comes with an image, while none from MLS scanned data. There are limitations of TLS for strata building survey such as water and glass window but this study proved that acquiring data by TLS is better than using MLS.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

30

Giganto, Sara, Susana Martínez-Pellitero, Eduardo Cuesta, Víctor M. Meana und Joaquín Barreiro. „Analysis of Modern Optical Inspection Systems for Parts Manufactured by Selective Laser Melting“. Sensors 20, Nr. 11 (04.06.2020): 3202. http://dx.doi.org/10.3390/s20113202.

Der volle Inhalt der Quelle

Annotation:

Metal additive manufacturing (AM) allows obtaining functional parts with the possibility of optimizing them topologically without affecting system performance. This is of great interest for sectors such as aerospace, automotive, and medical–surgical. However, from a metrological point of view, the high requirements applied in these sectors constitute a challenge for inspecting these types of parts. Non-contact inspection has gained great relevance due to the rapid verification of AM parts. Optical measurement systems (OMSs) are being increasingly adopted for geometric dimensioning and tolerancing (GD&T) verification within the context of Industry 4.0. In this paper, the suitability (advantages and limitations) of five different OMSs (based on laser triangulation, conoscopic holography, and structured light techniques) for GD&T verification of parts manufactured by selective laser melting (SLM) is analyzed. For this purpose, a specific testing part was designed and SLM-manufactured in 17-4PH stainless steel. Once the part was measured by contact (obtaining the reference GD&T values), it was optically measured. The scanning results allow comparing the OMSs in terms of their inspection speed as well as dimensional and geometrical accuracy. As a result, two portable systems (handheld laser triangulation and structured blue-light scanners) were identified as the most accurate optical techniques for scanning SLM parts.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

31

Yang, Sungwook, Joseph N. Martel, Louis A. Lobes und Cameron N. Riviere. „Techniques for robot-aided intraocular surgery using monocular vision“. International Journal of Robotics Research 37, Nr. 8 (Juli 2018): 931–52. http://dx.doi.org/10.1177/0278364918778352.

Der volle Inhalt der Quelle

Annotation:

This paper presents techniques for robot-aided intraocular surgery using monocular vision in order to overcome erroneous stereo reconstruction in an intact eye. We propose a new retinal surface estimation method based on a structured-light approach. A handheld robot known as the Micron enables automatic scanning of a laser probe, creating projected beam patterns on the retinal surface. Geometric analysis of the patterns then allows planar reconstruction of the surface. To realize automated surgery in an intact eye, monocular hybrid visual servoing is accomplished through a scheme that incorporates surface reconstruction and partitioned visual servoing. We investigate the sensitivity of the estimation method according to relevant parameters and also evaluate its performance in both dry and wet conditions. The approach is validated through experiments for automated laser photocoagulation in a realistic eye phantom in vitro. Finally, we present the first demonstration of automated intraocular laser surgery in porcine eyes ex vivo.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

32

Salgues, H., H. Macher und T. Landes. „EVALUATION OF MOBILE MAPPING SYSTEMS FOR INDOOR SURVEYS“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIV-4/W1-2020 (03.09.2020): 119–25. http://dx.doi.org/10.5194/isprs-archives-xliv-4-w1-2020-119-2020.

Der volle Inhalt der Quelle

Annotation:

Abstract. With their high recording rate of hundreds of thousands of points acquired per second, speed of execution and a remote acquisition mode, SLAM based mobile mapping systems (MMS) are a very powerful solution for capturing 3D point clouds in real time, simply by walking in the area of interest. Regarding indoor surveys, these MMS have been integrated in handheld or backpack solutions and become fast scanning sensors. Despite their advantages, the geometric accuracy of 3D point clouds guaranteed with these sensors is lower than the one reachable with static TLS. In this paper the effectiveness of two recent mobile mapping systems namely the GeoSLAM ZEB-REVO RT and the more recent GreenValley LiBackPack C50 is investigated for indoor surveys. In order to perform a reliable assessment study, several datasets produced with each sensor are compared to the high-cost georeferenced point cloud obtained with static laser scanning target-based technique.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

33

Ortiz-Coder, P., und R. Cabecera. „ACCURATE 3D RECONSTRUCTION USING A VIDEOGRAMMETRIC DEVICE FOR HERITAGE SCENARIOS“. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVI-M-1-2021 (28.08.2021): 499–506. http://dx.doi.org/10.5194/isprs-archives-xlvi-m-1-2021-499-2021.

Der volle Inhalt der Quelle

Annotation:

Abstract. In recent years, handheld laser scanning systems have been developed for documenting architectural heritage, among other applications. In this article we present a new alternative for the 3D documentation of historical heritage based on videogrammetry. For this purpose, a prototype has been designed with two cameras, a high resolution camera and a VGA camera which, when connected to a tablet, allow the user to establish a guidance system to ensure that the trajectory is not lost and enables highly flexible and long-lasting movements over time. This paper unveils the operation of the filtering and image selection system to finally proceed to an evaluation of the prototype in three areas of an archaeological site, called “Casa del Mitreo” in the city of Mérida (Spain). The results are compared to the Faro Focus 3D X330 laser scanner, yielding very similar accuracies and a capture time about 17 times faster than the 3D laser scanner. The article therefore proposes a real alternative to 3D data acquisition systems in applications for the graphic documentation of architectural and archaeological heritage.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

34

ESPINASSE, M., D. GRIVET, N. CAMPOLMI, E. CINOTTI, JL PERROT, B. LABEILLE, F. CAMBAZARD et al. „Agreement between in vivo confocal scanning laser microscopy with a handheld microscope and histology in eyelid and conjunctival tumours“. Acta Ophthalmologica 91 (August 2013): 0. http://dx.doi.org/10.1111/j.1755-3768.2013.2641.x.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

35

Cui, Li und Dong. „Structural 3D Reconstruction of Indoor Space for 5G Signal Simulation with Mobile Laser Scanning Point Clouds“. Remote Sensing 11, Nr. 19 (27.09.2019): 2262. http://dx.doi.org/10.3390/rs11192262.

Der volle Inhalt der Quelle

Annotation:

3D modelling of indoor environment is essential in smart city applications such as building information modelling (BIM), spatial location application, energy consumption estimation, and signal simulation, etc. Fast and stable reconstruction of 3D models from point clouds has already attracted considerable research interest. However, in the complex indoor environment, automated reconstruction of detailed 3D models still remains a serious challenge. To address these issues, this paper presents a novel method that couples linear structures with three-dimensional geometric surfaces to automatically reconstruct 3D models using point cloud data from mobile laser scanning. In our proposed approach, a fully automatic room segmentation is performed on the unstructured point clouds via multi-label graph cuts with semantic constraints, which can overcome the over-segmentation in the long corridor. Then, the horizontal slices of point clouds with individual room are projected onto the plane to form a binary image, which is followed by line extraction and regularization to generate floorplan lines. The 3D structured models are reconstructed by multi-label graph cuts, which is designed to combine segmented room, line and surface elements as semantic constraints. Finally, this paper proposed a novel application that 5G signal simulation based on the output structural model to aim at determining the optimal location of 5G small base station in a large-scale indoor scene for the future. Four datasets collected using handheld and backpack laser scanning systems in different locations were used to evaluate the proposed method. The results indicate our proposed methodology provides an accurate and efficient reconstruction of detailed structured models from complex indoor scenes.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

36

Liang, Xinlian, Yunsheng Wang, Anttoni Jaakkola, Antero Kukko, Harri Kaartinen, Juha Hyyppa, Eija Honkavaara und Jingbin Liu. „Forest Data Collection Using Terrestrial Image-Based Point Clouds From a Handheld Camera Compared to Terrestrial and Personal Laser Scanning“. IEEE Transactions on Geoscience and Remote Sensing 53, Nr. 9 (September 2015): 5117–32. http://dx.doi.org/10.1109/tgrs.2015.2417316.

Der volle Inhalt der Quelle

APA, Harvard, Vancouver, ISO und andere Zitierweisen

37

Russhakim, N. A. S., M. F. M. Ariff, Z. Majid, K. M. Idris, N. Darwin, M. A. Abbas, K. Zainuddin und A. R. Yusoff. „THE SUITABILITY OF TERRESTRIAL LASER SCANNING FOR BUILDING SURVEY AND MAPPING APPLICATIONS“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W9 (31.01.2019): 663–70. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w9-663-2019.

Der volle Inhalt der Quelle

Annotation:

Abstract. The popularity of Terrestrial Laser Scanner (TLS) has been introduced into a field of surveying and has increased dramatically especially in producing the 3D model of the building. The used of terrestrial laser scanning (TLS) is becoming rapidly popular because of its ability in several applications, especially the ability to observe complex documentation of complex building and observe millions of point cloud in three-dimensional in a short period. Users of building plan usually find it difficult to translate the traditional two-dimensional (2D) data on maps they see on a flat piece of paper to three-dimensional (3D). The TLS is able to record thousands of point clouds which contains very rich of geometry details and made the processing usually takes longer time. In addition, the demand of building survey work has made the surveyors need to obtain the data with full of accuracy and time saves. Therefore, the aim of this study is to study the limitation uses of TLS and its suitability for building survey and mapping. In this study, the efficiency of TLS Leica C10 for building survey was determined in term of its accuracy and comparing with Zeb-Revo Handheld Mobile Laser Scanning (MLS) and the distometer. The accuracy for scanned data from both, TLS and MLS were compared with the Distometer by using root mean square error (RMSE) formula. Then, the 3D model of the building for both data, TLS and MLS were produced to analyze the visualization for different type of scanners. The software used; Autodesk Recap, Autodesk Revit, Leica Cyclone Software, Autocad Software and Geo Slam Software. The RMSE for TLS technique is 0.001m meanwhile, RMSE for MLS technique is 0.007m. The difference between these two techniques is 0.006m. The 3D model of building for both models did not have too much different but the scanned data from TLS is much easier to process and generate the 3D model compared to scanned data from MLS. It is because the scanned data from TLS comes with an image, while none from MLS scanned data. There are limitations of TLS for building survey such as water and glass window but this study proved that acquiring data by TLS is better than using MLS.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

38

Thilmany, Jean. „Outside In“. Mechanical Engineering 131, Nr. 08 (01.08.2009): 38–41. http://dx.doi.org/10.1115/1.2009-aug-5.

Der volle Inhalt der Quelle

Annotation:

This article discusses reverse engineering software is slowly changing the way design engineers do their everyday jobs. With the pervasiveness of computer-aided design packages, reverse engineering technology has become a practical tool to create a 3D virtual model of an existing physical part. This model is then available to be used in 3D CAD, computer-aided manufacturing, or other computer-aided engineering applications. The reverse engineering process needs hardware and software that work together. The hardware is used to measure an object, and the software reconstructs it as a 3D model. The physical object can be measured using 3D scanning technologies such as a coordinate measuring machine, laser scanner, structured light digitizer, or computed tomography. The wider accessibility of handheld-laser scanners and portable CMMs like the one used at Excel Foundry means more companies can afford reverse engineering for their own unique ends. The scanner has turned out to be equally useful for engineering and for local archeological and preservation projects; and so far, it has been used to help preserve endangered artifacts.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

39

Watermann, Anna, Rita Gieringer, Anna-Maria Bauer, Sven Kurch, Ralf Kiesslich, Wolfgang Tremel, Jan Gosepath und Juergen Brieger. „Fluorescein- and EGFR-Antibody Conjugated Silica Nanoparticles for Enhancement of Real-time Tumor Border Definition Using Confocal Laser Endomicroscopy in Squamous Cell Carcinoma of the Head and Neck“. Nanomaterials 9, Nr. 10 (26.09.2019): 1378. http://dx.doi.org/10.3390/nano9101378.

Der volle Inhalt der Quelle

Annotation:

Intraoperative definition of tumor free resection margins in head and neck cancer is challenging. In the current proof-of-principle study we evaluated a novel silica nanoparticle-based agent for its potential use as contrast enhancer. We synthesized silica nanoparticles with an average size of 45 nm and modified these particles with the fluorescence stain fluorescein isocyanate (FITC) for particle detection and with epidermal growth factor receptor (EGFR)-targeting antibodies for enhanced tumor specificity. The nanoparticles exhibited good biocompatibility and could be detected in vitro and in vivo by confocal laser scanning microscopy. Additionally, we show in an ex vivo setting that these modified nanoparticles specifically bind to tumor samples and could be detected using a handheld confocal fluorescence endomicroscope. From a clinical point of view, we believe that this method could be used for tumor border contrast enhancement and for better intraoperative definition of R-0 tumor resection.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

40

Hunčaga, Milan, Juliána Chudá, Julián Tomaštík, Martina Slámová, Milan Koreň und František Chudý. „The Comparison of Stem Curve Accuracy Determined from Point Clouds Acquired by Different Terrestrial Remote Sensing Methods“. Remote Sensing 12, Nr. 17 (24.08.2020): 2739. http://dx.doi.org/10.3390/rs12172739.

Der volle Inhalt der Quelle

Annotation:

The knowledge of tree characteristics, especially the shape of standing trees, is important for living tree volume estimation, the computation of a wide range of forest stand features, and the evaluation of stand stability. Nowadays, nondestructive and accurate approaches to data collection in the forest environment are required. Therefore, the implementation of accurate point cloud-based information in the field of forest inventory has become increasingly required. We evaluated the stem curves of the lower part of standing trees (diameters at heights of 0.3 m to 8 m). The experimental data were acquired from three point cloud datasets, which were created through different approaches to three-dimensional (3D) environment modeling (varying in terms of data acquisition and processing time, acquisition costs, and processing complexity): terrestrial laser scanning (TLS), close-range photogrammetry (CRP), and handheld mobile laser scanning (HMLS) with a simultaneous localization and mapping algorithm (SLAM). Diameter estimation errors varied across heights of cross sections and methods. The average root mean squared error (RMSE) of all cross sections for the specific methods was 1.03 cm (TLS), 1.26 cm (HMLS), and 1.90 cm (CRP). TLS and CRP reached the lowest RMSE at a height of 1.3 m, while for HMLS, it was at the height of 8 m. Our findings demonstrated that the accuracy of measurements of the standing tree stem curve was comparable for the usability of all three devices in forestry practices.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

41

Comesaña-Cebral, Lino, Joaquín Martínez-Sánchez, Henrique Lorenzo und Pedro Arias. „Individual Tree Segmentation Method Based on Mobile Backpack LiDAR Point Clouds“. Sensors 21, Nr. 18 (08.09.2021): 6007. http://dx.doi.org/10.3390/s21186007.

Der volle Inhalt der Quelle

Annotation:

Individual tree (IT) segmentation is crucial for forest management, supporting forest inventory, biomass monitoring or tree competition analysis. Light detection and ranging (LiDAR) is a prominent technology in this context, outperforming competing technologies. Aerial laser scanning (ALS) is frequently used for forest documentation, showing good point densities at the tree-top surface. Even though under-canopy data collection is possible with multi-echo ALS, the number of points for regions near the ground in leafy forests drops drastically, and, as a result, terrestrial laser scanners (TLS) may be required to obtain reliable information about tree trunks or under-growth features. In this work, an IT extraction method for terrestrial backpack LiDAR data is presented. The method is based on DBSCAN clustering and cylinder voxelization of the volume, showing a high detection rate (∼90%) for tree locations obtained from point clouds, and low commission and submission errors (accuracy over 93%). The method includes a sensibility assessment to calculate the optimal input parameters and adapt the workflow to real-world data. This approach shows that forest management can benefit from IT segmentation, using a handheld TLS to improve data collection productivity.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

42

Fottner, C., E. Mettler, M. Goetz, E. Schirrmacher, M. Anlauf, D. Strand, R. Schirrmacher et al. „In Vivo Molecular Imaging of Somatostatin Receptors in Pancreatic Islet Cells and Neuroendocrine Tumors by Miniaturized Confocal Laser-Scanning Fluorescence Microscopy“. Endocrinology 151, Nr. 5 (16.03.2010): 2179–88. http://dx.doi.org/10.1210/en.2009-1313.

Der volle Inhalt der Quelle

Annotation:

The aim of the study was to evaluate real time in vivo molecular imaging of somatostatin receptors (sstrs) using a handheld miniaturized confocal laser scan microscope (CLM) in conjunction with fluorescein-labeled octreotate (OcF) in healthy mice and murine models of neuroendocrine tumors. For CLM a small rigid probe (diameter 7 mm) with an integrated single line laser (488 nm) was used (optical slice thickness 7 μm; lateral resolution 0.7 μm). OcF was synthesized via Fmoc solid-phase peptide synthesis and purified by HPLC showing high-affinity binding to the sstr2 (IC50 6.2 nmol). For in vitro evaluation, rat and human pancreatic cancer cells were used and characterized with respect to its sstr subtype expression and functional properties. For in vivo confocal imaging, healthy mouse pancreatic islet and renal tubular cells as well as immunoincompetent nude mice harboring sstr-expressing tumors were evaluated. Incubation of sstr-positive cells with OcF showed a specific time- and dose-dependent staining of sstr-positive cells. CLM showed rapid internalization and homogenous cytoplasmatic distribution. After systemic application to mice (n = 8), specific time-dependent internalization and cytoplasmatic distribution into pancreatic islet cells and tubular cells of the renal cortex was recorded. After injection in tumor-harboring nude mice (n = 8), sstr-positive cells selectively displayed a cell surface and cytoplasmatic staining. CLM-targeted biopsies detected sstr-positive tumor cells with a sensitivity of 87.5% and a specificity of 100% as correlated with ex vivo immunohistochemistry. CLM with OcF permits real-time molecular, functional, and morphological imaging of sstr-expressing cell structures, allowing the specific visualization of pancreatic islet cells and neuroendocrine tumors in vivo.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

43

Zhou, Sanzhang, Feng Kang, Wenbin Li, Jiangming Kan, Yongjun Zheng und Guojian He. „Extracting Diameter at Breast Height with a Handheld Mobile LiDAR System in an Outdoor Environment“. Sensors 19, Nr. 14 (21.07.2019): 3212. http://dx.doi.org/10.3390/s19143212.

Der volle Inhalt der Quelle

Annotation:

Mobile laser scanning (MLS) is widely used in the mapping of forest environments. It has become important for extracting the parameters of forest trees using the generated environmental map. In this study, a three-dimensional point cloud map of a forest area was generated by using the Velodyne VLP-16 LiDAR system, so as to extract the diameter at breast height (DBH) of individual trees. The Velodyne VLP-16 LiDAR system and inertial measurement units (IMU) were used to construct a mobile measurement platform for generating 3D point cloud maps for forest areas. The 3D point cloud map in the forest area was processed offline, and the ground point cloud was removed by the random sample consensus (RANSAC) algorithm. The trees in the experimental area were segmented by the European clustering algorithm, and the DBH component of the tree point cloud was extracted and projected onto a 2D plane, fitting the DBH of the trees using the RANSAC algorithm in the plane. A three-dimensional point cloud map of 71 trees was generated in the experimental area, and estimated the DBH. The mean and variance of the absolute error were 0.43 cm and 0.50, respectively. The relative error of the whole was 2.27%, the corresponding variance was 15.09, and the root mean square error (RMSE) was 0.70 cm. The experimental results were good and met the requirements of forestry mapping, and the application value and significance were presented.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

44

Che, E., M. J. Olsen, C. Parrish und J. Jung. „PAVEMENT MARKING REFLECTIVITY EVALUATION THROUGH RADIOMETRIC CALIBRATION OF THE LEICA P40 TERRESTRIAL LASER SCANNER“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W5 (29.05.2019): 333–39. http://dx.doi.org/10.5194/isprs-annals-iv-2-w5-333-2019.

Der volle Inhalt der Quelle

Annotation:

Abstract. Pavement markings serve as important traffic control devices, delineating traffic lanes and conveying regulations, guidance or warnings to roadway users. To ensure that pavement markings are clearly visible, especially at night, transportation agencies periodically assess the retroreflectivity of various categories of markings through manual approaches at discrete location. Because the radiometric information such as intensity in the lidar data cannot inherently be considered as a retroreflectivity measurement without additional processing, this study rigorously assesses the ability to determine pavement marking retroreflectivity from the Leica ScanStation P40 through radiometric calibration. For the evaluation, data were collected at a study site in Philomath, Oregon using the Leica P40, Leica Pegasus: Two mobile lidar system, and a handheld retroreflectometer as a reference. The results show that, with appropriate calibration, the lidar data can adequately assess the retroreflectivity of pavement markings. Additionally, while corrections have been proposed for range and angle of incidence, these corrections are not straightforward to apply for retroreflective materials, as will be discussed herein. While mobile lidar technology is ideal for a system-wide asset management framework, terrestrial laser scanning can be utilized for detailed investigations at sites such as intersections with highly variable wear where both can enable significant cost savings and applied for a variety of purposes simultaneously including asset management and project development.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

45

Patrucco, G., F. Rinaudo und A. Spreafico. „MULTI-SOURCE APPROACHES FOR COMPLEX ARCHITECTURE DOCUMENTATION: THE “PALAZZO DUCALE” IN GUBBIO (PERUGIA, ITALY)“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W11 (05.05.2019): 953–60. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w11-953-2019.

Der volle Inhalt der Quelle

Annotation:

Abstract. Nowadays, the employment of rapid mapping solutions for architectural survey is more and more considered, not only for the strong reduction of the primary data acquisition times, but also thanks to their adaptability to various contexts, especially in the framework of Cultural Heritage documentation where tailored solutions are required. The combined use of Mobile Mapping Systems (MMS), Unmanned Aerial Vehicles (UAV) for close range aerial image acquisition, and Terrestrial Laser Scanning (TLS) seems to be an effective solution for the architectonic scale compliant to the level of detail and accuracy of 1&thinsp;:&thinsp;200, and 1&thinsp;:&thinsp;100 scales. The present research tries to evaluate the use of a handheld MMS, the ZEB-Revo RT by Geoslam, an UAV, the DJI Mavic Pro, and a LiDAR system, the Faro Focus3D S 120 by CAM2. The complex case of the documentation metric survey of Palazzo Ducale in Gubbio, the Montefeltro’s Palace, now hosting the museum of itself, allows the comparison of the effectiveness of the used technologies.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

46

Belykh, Evgenii, Jubran Jubran, Laeth George, Liudmila Bardonova, Deborah Healey, Joseph Georges, Chad Quarles et al. „BIMG-03. MOLECULAR IMAGING OF GLUCOSE METABOLISM FOR INTRAOPERATIVE FLUORESCENCE GUIDANCE DURING GLIOMA SURGERY“. Neuro-Oncology Advances 3, Supplement_1 (01.03.2021): i1. http://dx.doi.org/10.1093/noajnl/vdab024.002.

Der volle Inhalt der Quelle

Annotation:

Abstract PURPOSE This study evaluated the utility of using molecular imaging of fluorescent glucose analog 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG) as a discriminatory marker for intraoperative tumor border identification in a mouse glioma model. PROCEDURES 2-NBDG and were assessed in GL261 and U251 orthotopic tumor bearing mice. Intraoperative fluorescence of 2-NBDG administered topical and intravenous in normal and tumor regions was assessed with operating microscope, handheld confocal laser scanning endomicroscope (CLE) and benchtop confocal laser scanning microscope (LSM). Additionally, 2-NBDG fluorescence in tumors was compared to 5-aminolevulinic acid-induced protoporphyrin IX fluorescence. RESULTS Intravenously administered 2-NBDG was detectable in brain tumor and absent in contralateral normal brain parenchyma on wide field operating microscopy imaging. Intraoperative and benchtop CLE showed preferential 2-NBDG accumulation in the cytoplasm of glioma cells (tumor-background ratio of 2.76±0.43). Topically administered 2-NBDG did not create a sufficient tumor-background contrast for white field operating microscopy imaging, or under benchtop LSM (tumor-background ratio 1.42 ± 0.72). However, topical 2-NBDG did create sufficient contrast to evaluate cellular tissue architecture and differentiate tumor cells from normal brain parenchyma. PpIX imaging resulted in a more specific delineation of gross tumor margins than IV or topical 2-NBDG, and a significantly higher tumor-normal brain fluorescence intensity ratio. CONCLUSION After intravenous administration, 2-NBDG selectively accumulated in the experimental brain tumors and provided bright contrast under wide field fluorescence imaging with a clinical grade operating microscope. Topical 2-NBDG was able to create a sufficient contrast to differentiate tumor from normal brain cells based on visualization of cellular architecture with CLE. 5-ALA demonstrated superior specificity in outlining tumor margins and significantly higher tumor-background contrast. Given its non-toxicity, using 2-NBDG as a topical molecular marker for noninvasive in vivo intraoperative microscopy is encouraging, and warrants further clinical evaluation.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

47

Gollob, Christoph, Tim Ritter, Ralf Kraßnitzer, Andreas Tockner und Arne Nothdurft. „Measurement of Forest Inventory Parameters with Apple iPad Pro and Integrated LiDAR Technology“. Remote Sensing 13, Nr. 16 (07.08.2021): 3129. http://dx.doi.org/10.3390/rs13163129.

Der volle Inhalt der Quelle

Annotation:

The estimation of single tree and complete stand information is one of the central tasks of forest inventory. In recent years, automatic algorithms have been successfully developed for the detection and measurement of trees with laser scanning technology. Nevertheless, most of the forest inventories are nowadays carried out with manual tree measurements using traditional instruments. This is due to the high investment costs for modern laser scanner equipment and, in particular, the time-consuming and incomplete nature of data acquisition with stationary terrestrial laser scanners. Traditionally, forest inventory data are collected through manual surveys with calipers or tapes. Practically, this is both labor and time-consuming. In 2020, Apple implemented a Light Detection and Ranging (LiDAR) sensor in the new Apple iPad Pro (4th Gen) and iPhone Pro 12. Since then, access to LiDAR-generated 3D point clouds has become possible with consumer-level devices. In this study, an Apple iPad Pro was tested to produce 3D point clouds, and its performance was compared with a personal laser scanning (PLS) approach to estimate individual tree parameters in different forest types and structures. Reference data were obtained by traditional measurements on 21 circular forest inventory sample plots with a 7 m radius. The tree mapping with the iPad showed a detection rate of 97.3% compared to 99.5% with the PLS scans for trees with a lower diameter at a breast height (dbh) threshold of 10 cm. The root mean square error (RMSE) of the best dbh measurement out of five different dbh modeling approaches was 3.13 cm with the iPad and 1.59 cm with PLS. The data acquisition time with the iPad was approximately 7.51 min per sample plot; this is twice as long as that with PLS but 2.5 times shorter than that with traditional forest inventory equipment. In conclusion, the proposed forest inventory with the iPad is generally feasible and achieves accurate and precise stem counts and dbh measurements with efficient labor effort compared to traditional approaches. Along with future technological developments, it is expected that other consumer-level handheld devices with integrated laser scanners will also be developed beyond the iPad, which will serve as an accurate and cost-efficient alternative solution to the approved but relatively expensive TLS and PLS systems. Such a development would be mandatory to broadly establish digital technology and fully automated routines in forest inventory practice. Finally, high-level progress is generally expected for the broader scientific community in forest ecosystem monitoring, as the collection of highly precise 3D point cloud data is no longer hindered by financial burdens.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

48

Tenschert, R. „CATHEDRAL NORTE DAME IN PARIS – THE INSCRIPTION OF THE SOUTH TRANSEPTS FAÇADE: MEDIEVAL RELICT OR 19th CENTURY RECREATION?“ ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W15 (26.08.2019): 1141–47. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w15-1141-2019.

Der volle Inhalt der Quelle

Annotation:

Abstract. While non-destructive 3D technologies offer outstanding possibilities for analysing shape and similarities in architectural details, and for the monitoring of weathering effects, it has so far been used only rarely for these purposes. This paper shows the application and analysis of high resolution, handheld, optical tracked laser scanning on an inscription at the cathedral of Notre Dame in Paris. The transept’s south façade carries a latin inscription dating from 1258, and the common research opinion is that the inscription was copied and renewed during the mid-19th century restoration. In the course of an on-site research campaign, some doubt as to the veracity of this theory arose. Essential questions regarding the inscription concern the workflows of both medieval craftsmen and those from the 19th century. The project’s aim was to analyse the inscription for its shape and for any traces left by the craftsmen. Another key question focussed on the originality and authenticity of the inscription. The analysis of the high-resolution 3D data set has confirmed the initial visual impression of differences between the stones and shown that most of the inscription is the 13th century original with only a few parts replaced. The analysis also revealed that the ribbon and the letters must have been carved before the stones were placed. An investigation using historical transcripts, comparative examples and contextual reflections with a detailed analysis of the individual letters also revealed possible changes in the wording of the inscription made during the restoration. A discussion of the possible variants supported by virtual visualisations is also presented.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

49

Polewski, P., A. Erickson, W. Yao, N. Coops, P. Krzystek und U. Stilla. „OBJECT-BASED COREGISTRATION OF TERRESTRIAL PHOTOGRAMMETRIC AND ALS POINT CLOUDS IN FORESTED AREAS“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-3 (06.06.2016): 347–54. http://dx.doi.org/10.5194/isprsannals-iii-3-347-2016.

Der volle Inhalt der Quelle

Annotation:

Airborne Laser Scanning (ALS) and terrestrial photogrammetry are methods applicable for mapping forested environments. While ground-based techniques provide valuable information about the forest understory, the measured point clouds are normally expressed in a local coordinate system, whose transformation into a georeferenced system requires additional effort. In contrast, ALS point clouds are usually georeferenced, yet the point density near the ground may be poor under dense overstory conditions. In this work, we propose to combine the strengths of the two data sources by co-registering the respective point clouds, thus enriching the georeferenced ALS point cloud with detailed understory information in a fully automatic manner. Due to markedly different sensor characteristics, coregistration methods which expect a high geometric similarity between keypoints are not suitable in this setting. Instead, our method focuses on the object (tree stem) level. We first calculate approximate stem positions in the terrestrial and ALS point clouds and construct, for each stem, a descriptor which quantifies the 2D and vertical distances to other stem centers (at ground height). Then, the similarities between all descriptor pairs from the two point clouds are calculated, and standard graph maximum matching techniques are employed to compute corresponding stem pairs (tiepoints). Finally, the tiepoint subset yielding the optimal rigid transformation between the terrestrial and ALS coordinate systems is determined. We test our method on simulated tree positions and a plot situated in the northern interior of the Coast Range in western Oregon, USA, using ALS data (76 x 121 m2) and a photogrammetric point cloud (33 x 35 m2) derived from terrestrial photographs taken with a handheld camera. Results on both simulated and real data show that the proposed stem descriptors are discriminative enough to derive good correspondences. Specifically, for the real plot data, 24 corresponding stems were coregistered with an average 2D position deviation of 66 cm.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

50

Polewski, P., A. Erickson, W. Yao, N. Coops, P. Krzystek und U. Stilla. „OBJECT-BASED COREGISTRATION OF TERRESTRIAL PHOTOGRAMMETRIC AND ALS POINT CLOUDS IN FORESTED AREAS“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-3 (06.06.2016): 347–54. http://dx.doi.org/10.5194/isprs-annals-iii-3-347-2016.

Der volle Inhalt der Quelle

Annotation:

Airborne Laser Scanning (ALS) and terrestrial photogrammetry are methods applicable for mapping forested environments. While ground-based techniques provide valuable information about the forest understory, the measured point clouds are normally expressed in a local coordinate system, whose transformation into a georeferenced system requires additional effort. In contrast, ALS point clouds are usually georeferenced, yet the point density near the ground may be poor under dense overstory conditions. In this work, we propose to combine the strengths of the two data sources by co-registering the respective point clouds, thus enriching the georeferenced ALS point cloud with detailed understory information in a fully automatic manner. Due to markedly different sensor characteristics, coregistration methods which expect a high geometric similarity between keypoints are not suitable in this setting. Instead, our method focuses on the object (tree stem) level. We first calculate approximate stem positions in the terrestrial and ALS point clouds and construct, for each stem, a descriptor which quantifies the 2D and vertical distances to other stem centers (at ground height). Then, the similarities between all descriptor pairs from the two point clouds are calculated, and standard graph maximum matching techniques are employed to compute corresponding stem pairs (tiepoints). Finally, the tiepoint subset yielding the optimal rigid transformation between the terrestrial and ALS coordinate systems is determined. We test our method on simulated tree positions and a plot situated in the northern interior of the Coast Range in western Oregon, USA, using ALS data (76 x 121 m2) and a photogrammetric point cloud (33 x 35 m2) derived from terrestrial photographs taken with a handheld camera. Results on both simulated and real data show that the proposed stem descriptors are discriminative enough to derive good correspondences. Specifically, for the real plot data, 24 corresponding stems were coregistered with an average 2D position deviation of 66 cm.

APA, Harvard, Vancouver, ISO und andere Zitierweisen

Zeitschriftenartikel zum Thema „Handheld laser scanning“

Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an