Bibliografie tematiche / Photometric

Letteratura scientifica selezionata sul tema "Photometric"

Autore: Grafiati
Pubblicato: 4 giugno 2021
Ultima modifica: 28 maggio 2022

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Articoli di riviste sul tema "Photometric"

1

Evans, D. W., M. Riello, F. De Angeli, J. M. Carrasco, P. Montegriffo, C. Fabricius, C. Jordi et al. "Gaia Photometric Catalogue: the calibration of the DR2 photometry". Proceedings of the International Astronomical Union 14, A30 (agosto 2018): 466–70. http://dx.doi.org/10.1017/s174392131900512x.

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AbstractGaia DR2 was released in April 2018 and contains a photometric catalogue of more than 1 billion sources. This release contains colour information in the form of integrated BP and RP photometry in addition to the latest G-band photometry. The level of uncertainty can be as good as 2 mmag with some residual systematics at the 10 mmag level. The addition of colour information greatly enhances the value of the photometric data for the scientific community. A high level overview of the photometric processing, with a focus on the improvements with respect to Gaia DR1, was given. The definition of the Gaia photometric system, a crucial part of the calibration of the photometry, was also explained. Finally, some of the photometric improvements expected for the next data release were described.
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Wittman, D., P. Riechers e V. E. Margoniner. "Photometric Redshifts and Photometry Errors". Astrophysical Journal 671, n. 2 (16 novembre 2007): L109—L112. http://dx.doi.org/10.1086/525020.

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3

Fotopoulou, S., e S. Paltani. "CPz: Classification-aided photometric-redshift estimation". Astronomy & Astrophysics 619 (30 ottobre 2018): A14. http://dx.doi.org/10.1051/0004-6361/201730763.

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Abstract (sommario):
Broadband photometry offers a time and cost effective method to reconstruct the continuum emission of celestial objects. Thus, photometric redshift estimation has supported the scientific exploitation of extragalactic multiwavelength surveys for more than twenty years. Deep fields have been the backbone of galaxy evolution studies and have brought forward a collection of various approaches in determining photometric redshifts. In the era of precision cosmology, with the upcoming Euclid and LSST surveys, very tight constraints are put on the expected performance of photometric redshift estimation using broadband photometry, thus new methods have to be developed in order to reach the required performance. We present a novel automatic method of optimizing photometric redshift performance, the classification-aided photometric redshift estimation (CPz). The main feature of CPz is the unified treatment of all classes of objects detected in extragalactic surveys: galaxies of any type (passive, starforming and starbursts), active galactic nuclei (AGN), quasi-stellar objects (QSO), stars and also includes the identification of potential photometric redshift catastrophic outliers. The method operates in three stages. First, the photometric catalog is confronted with star, galaxy and QSO model templates by means of spectral energy distribution fitting. Second, three machine-learning classifiers are used to identify 1) the probability of each source to be a star, 2) the optimal photometric redshift model library set-up for each source and 3) the probability to be a photometric redshift catastrophic outlier. Lastly, the final sample is assembled by identifying the probability thresholds to be applied on the outcome of each of the three classifiers. Hence, with the final stage we can create a sample appropriate for a given science case, for example favoring purity over completeness. We apply our method to the near-infrared VISTA public surveys, matched with optical photometry from CFHTLS, KIDS and SDSS, mid-infrared WISE photometry and ultra-violet photometry from the Galaxy Evolution Explorer (GALEX). We show that CPz offers improved photometric redshift performance for both normal galaxies and AGN without the need for extra X-ray information.
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Li, Xiao Pan, Cheng Yang, Li Zhou e Hai Tao Yang. "Photometric Data Procession of the Swift/UVOT Instrument". Advanced Materials Research 989-994 (luglio 2014): 3489–92. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.3489.

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The Ultraviolet/Optical Telescope (UVOT) which is one of three scientific instruments onboard the NASA-led Swift satellite provides simultaneous ultraviolet and optical photometric data. We present the installing procedures of HEASoft software and the detailed method for using the HEASoft in UVOT photometric data processions. We focus on the application of photometry processes, and present the photometry of Quasar PKS 0537-441. The analysis of the photometric data shows that this source has extreme variations in optical and ultraviolet bands and the shape of photometric flux curves in each band is excellently in agreement with each other.
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Walker, Alistair, Saul Adelman, Eugene Milone, Barbara Anthony-Twarog, Pierre Bastien, Wen Ping Chen, Steve Howell et al. "DIVISION B COMMISSION 25: ASTRONOMICAL PHOTOMETRY AND POLARIMETRY". Proceedings of the International Astronomical Union 11, T29A (agosto 2015): 159–70. http://dx.doi.org/10.1017/s1743921316000727.

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Commission 25 (C25) deals with the techniques and issues involved with the measurement of optical and infrared radiation intensities and polarization from astronomical sources. As such, in recent years attention has focused on photometric standard stars, atmospheric extinction, photometric passbands, transformation between systems, nomenclature, and observing and reduction techniques. At the start of the trimester C25 changed its name from Stellar Photometry and Polarization to Astronomical Photometry and Polarization so as to explicitly include in its mandate particular issues arising from the measurement of resolved sources, given the importance of photometric redshifts of distant galaxies for many of the large photometric surveys now underway. We begin by summarizing commission activities over the 2012-2014 period, follow with a report on Polarimetry, continue with Photometry topics that have been of interest to C25 members, and conclude with a Vision for the Future.
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Tedesco, Edward F. "Archiving Asteroid Photometric Data". Highlights of Astronomy 9 (1992): 719–20. http://dx.doi.org/10.1017/s1539299600010169.

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AbstractCurrent programs which produce asteroid photometric data range from astrometry through visual and near-infrared photometry and spectrophotometry to thermal infrared (8 to 30 micrometers) photometry. These data are published in a variety of places including observatory publications, IAU Circulars, the Minor Planet Circulars, and various journals.
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Rufener, F. "Passbands and Photometric Systems". Highlights of Astronomy 7 (1986): 813–17. http://dx.doi.org/10.1017/s1539299600007334.

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AbstractSynthetic photometry must be used to accurately define the passbands which characterize a photometric system. On the one hand, the colour indices of the stars must be coherent with their absolute spectrophotometry; on the other hand, direct comparisons of model atmospheres with observations must be carried out without resorting to arbitrary transformations. A systematic evaluation procedure could be applied to various photometric systems.
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Pforr, Janine. "The Spitzer Extragalactic Representative Volume Survey - measuring photometric redshifts for ∼4 million galaxies - challenges and ways forward". Proceedings of the International Astronomical Union 15, S341 (novembre 2019): 157–61. http://dx.doi.org/10.1017/s1743921319002412.

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AbstractWe highlight the challenges as well as lessons learnt in the derivation of the photometric redshifts for ∼4 million galaxies at 0 < z ≲ 6 contained in the Spitzer Extragalactic Representative Volume Survey (SERVS) and summarise the photometric redshift results recently published in Pforr et al. (2019). The inhomogeneous nature of the ancillary photometry for SERVS presents a similar situation to the one future, large, extragalactic surveys with e.g. LSST and JWST will face. We employ template SED-fitting to determine photometric redshifts. Our comparison of photometric redshifts to ∼75.000 public, spectroscopic redshifts results in an average σNMAD of ∼0.038 and outlier fraction of 3.7% for sources with the best photometric coverage. We find that photometric redshifts are determined most robustly when filter bands are numerous and cover a wide wavelength range. We highlight some possible improvements for the photometric redshifts in SERVS in the future.
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Bessell, Michael S. "Photometric Systems". International Astronomical Union Colloquium 136 (1993): 22–39. http://dx.doi.org/10.1017/s025292110000734x.

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AbstractMulticolour photometry has historically been carried out within a variety of standard systems. With the advent of new detectors with different wavelength sensitivities to those of the original system and the use of subsets of secondary standards, many subtle and not so subtle changes have occurred to the original systems. However, by reverse engineering, the passbands of the modified standard systems can be determined which enables good realisation of theoretical colours and better passband matching for CCD-based photometry. In this paper, the various photometric systems will be discussed and compared and strategies will be outlined for ensuring that precise relative photometry is maintained in the future, in particular from area detectors.
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Zhou, Rongpu, Michael C. Cooper, Jeffrey A. Newman, Matthew L. N. Ashby, James Aird, Christopher J. Conselice, Marc Davis et al. "Deep ugrizY imaging and DEEP2/3 spectroscopy: a photometric redshift testbed for LSST and public release of data from the DEEP3 Galaxy Redshift Survey". Monthly Notices of the Royal Astronomical Society 488, n. 4 (25 luglio 2019): 4565–84. http://dx.doi.org/10.1093/mnras/stz1866.

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ABSTRACT We present catalogues of calibrated photometry and spectroscopic redshifts in the Extended Groth Strip, intended for studies of photometric redshifts (photo-z’s). The data includes ugriz photometry from Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) and Y-band photometry from the Subaru Suprime camera, as well as spectroscopic redshifts from the DEEP2, DEEP3, and 3D-HST surveys. These catalogues incorporate corrections to produce effectively matched-aperture photometry across all bands, based upon object size information available in the catalogue and Moffat profile point spread function fits. We test this catalogue with a simple machine learning-based photometric redshift algorithm based upon Random Forest regression, and find that the corrected aperture photometry leads to significant improvement in photo-z accuracy compared to the original SExtractor catalogues from CFHTLS and Subaru. The deep ugrizY photometry and spectroscopic redshifts are well suited for empirical tests of photometric redshift algorithms for LSST. The resulting catalogues are publicly available at http://d-scholarship.pitt.edu/36064/. We include a basic summary of the strategy of the DEEP3 Galaxy Redshift Survey to accompany the recent public release of DEEP3 data.
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Più fonti

Tesi sul tema "Photometric"

1

Halliday, Colin George. "Aspects of photometric titration". Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329513.

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2

Powell, Christopher. "Mutual illumination photometric stereo". Thesis, University of East Anglia, 2018. https://ueaeprints.uea.ac.uk/67065/.

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Many techniques have been developed in computer vision to recover three-dimensional shape from two-dimensional images. These techniques impose various combinations of assumptions/restrictions of conditions to produce a representation of shape (e.g. surface normals or a height map). Although great progress has been made it is a problem which remains far from solved. In this thesis we propose a new approach to shape recovery - namely `mutual illumination photometric stereo'. We exploit the presence of colourful mutual illumination in an environment to recover the shape of objects from a single image.
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3

Pocino, Yuste Andrea. "Cosmology with photometric redshift". Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671733.

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Els cartografiats de galàxies fotomètrics actuals i futurs observaran un gran volum de l’univers que ens permetrà acotar amb precisió el model cosmològic. Tanmateix, la capacitat de delimitar el model que tenen aquests cartografiats a través de les sondes cosmològiques depèn de la precisió i certesa amb les que es determina el redshift de les galàxies. Per tant, la determinació del redshift fotomètric i els seus efectes en les anàlisis cosmològiques han de ser tractats i estudiats curosament. En la primera part de la tesi, transformem la fotometria de simulacions que ja existeixen per imitar les mesures fotomètriques del Dark Energy Survey (DES). D’aquesta manera, esperem recuperar la distribució real del redshift fotomètric en simulacions, i així crear una base encara més realista per comprovar els resultats de les anàlisis cosmològiques de DES que fan us del redshift fotomètric. Per transformar les simulacions utilitzem diversos mètodes que transfereixen les propietats estadístiques de la fotometria d’observacions real a les simulacions. A la segona part de la tesi, utilitzem la tècnica del Self-Organizing Map per seleccionar galàxies per ser observades amb espectroscòpia, contribuint així al projecte C3R2 que vol establir un mapa correlacional entre l’espai de colors i redshift i omplir-ho amb informació espectroscòpica. En aquesta part també explorem l’espai de colors definit per la fotometria del Physics of the Accelerating Universe Survey (PAUS) per tal d’estudiar la cobertura del redshift espectroscòpic del seu espai de colors. Volem determinar la quantitat d’espai de color sense cobertura espectroscòpica perquè la falta de representació d’espectroscòpia pot ser una font de biaix quan la precisió dels redshifts fotomètrics és avaluada comparant-los amb redshifts espectroscòpics o quan els redshifts espectroscòpics s’utilitzen com a mostra d’entrenament per determinar els redshifts fotomètrics amb algoritmes d’entrenament. Finalment, explorem com la variació en la profunditat de les observacions des de terra combinades amb les d’Euclid afecta la precisió dels redshifts fotomètrics i, per tant, la capacitat de determinar els paràmetres cosmològics d’Euclid sobretot quan utilitza galaxy clustering i galaxy-galaxy lensing com a sondes cosmològiques. També estudiem com la densitat de les mostres de galàxies afecta la capacitat de delimitar els paràmetres cosmològics i quina és la configuració de bins tomogràfics de redshift que permet extreure la màxima informació per delimitar els paràmetres cosmològics. Per tal de dur a terme aquesta anàlisi, creem diverses distribucions realistes de redshift fotomètric basades en la simulació Flagship d’Euclid i utilitzem el formalisme de Fisher per fer una estimació de la capacitat d’acotament dels paràmetres cosmològics de les diferents configuracions de les mostres de galàxies.
Los cartografiados de galaxias fotométricos actuales y futuros observarán un gran volumen del universo que nos permitirá acotar con precisión el modelo cosmológico. Aun así, la capacidad de los cartografiados para delimitar el modelo a través de las sondas cosmológicas depende de la precisión y certeza con las que se determina el redshift de las galaxias. Por lo tanto, la determinación del redshift fotométrico y sus efectos en los análisis cosmológicos deben ser tratados y estudiados cuidadosamente. En la primera parte de la tesis, transformamos la fotometría de simulaciones que ya existen para imitar las mediciones fotométricas del Dark Energy Survey (DES). De esta forma, esperamos recuperar la distribución real del redshift fotométrico en simulaciones, y así crear una base aún más realista para comprobar los resultados de los análisis cosmológicos de DES que usan redshifts fotométricos. Para transformar las simulaciones utilizamos diversos métodos que transfieren las propiedades estadísticas de la fotometría de observaciones reales a las simulaciones. En la segunda parte de la tesis, utilizamos la técnica del Self-Organizing Map para seleccionar galaxias para ser observadas con espectroscopia, contribuyendo así al proyecto C3R2 que quiere establecer un mapa correlacional entre el espacio de colores y redshift y llenarlo con información espectroscópica. En esta parte también exploramos el espacio de colores definido por la fotometría del Physics of the Accelerating Universe Survey (PAUS) con tal de estudiar la cobertura del redshift espectroscópico de su espacio de colores. Queremos determinar la cantidad del espacio de color sin cobertura espectroscópica porque la falta de representación espectroscópica puede originar un sesgo cuando la precisión del redshift fotométrico se evalúa comparándolo con el redshift espectroscópico o cuando el redshift espectroscópico se utiliza como muestra de entrenamiento para determinar el redshift fotométrico con algoritmos de entrenamiento. Finalmente, exploramos como la variación en la profundidad de las observaciones desde tierra combinadas con las de Euclid afecta la precisión de los redshifts fotométricos y, por lo tanto, la capacidad de Euclid para determinar los parámetros cosmológicos sobre todo cuando se utilizan galaxy clustering y galaxy-galaxy lensing como sondas cosmológicas. También estudiamos como la densidad de las muestras de galaxias afecta la capacidad de acotar los parámetros cosmológicos y cuál es la configuración de bines tomográficos de redshift que permiten extraer la máxima información para delimitar los parámetros cosmológicos. Para llevar a cabo este análisis, creamos diversas distribuciones realistas de redshift fotométrico basadas en la simulación Flagship de Euclid y utilizamos el formalismo de Fisher para hacer una estimación de la capacidad de acotar los parámetros cosmológicos de las diferentes configuraciones de las muestras de galaxias.
Current and future photometric surveys will observe a large volume of the universe that will allow us to accurately constrain the cosmological model. However, the constraining power from cosmological probes of photometric surveys highly relies on the accuracy and precision with which we can determine the galaxies redshifts. Therefore, the determination of photometric redshifts (photo-zs) and their effect in cosmological analysis should be treated and studied carefully. In the first part of this thesis, we transform the photometry of existing simulations to mimic the photometric measurements of the Dark Energy Survey (DES). With this exercise, we expect to recover the real photo-z distribution in simulations, thus creating a more realistic environment to crosscheck the performance of DES in cosmological analyses that use photo-z. We transform the simulations using several method to transfer the statistical properties from the real observations photometry to the simulations. In the second part of the thesis, we use the Self-Organizing Map technique to select spectroscopic targets for the C3R2 program aimed at establishing the mapping between color and redshift space. We also explore the color space defined by the photometry of galaxies from the Physics of the Accelerating Universe Survey (PAUS) in order to study the spectroscopic redshift coverage of its color space. We want to quantify the regions of color space without spectroscopic redshifts because the lack of spectroscopic representation can be a source of bias when the accuracy of photo-zs is evaluated by comparing it to spectroscopic redshifts and when the spectroscopic redshifts are used to determine the photo- z with training-based algorithms. Lastly, we explore how the variation of the depth of ground-based observations combined with Euclid observations affects the accuracy and precision of the photo-z and thus the cosmological constraining power of Euclid focusing on photometric galaxy clustering and galaxy-galaxy lensing analyses. We also study how the number density of photometric galaxy samples affects the constraining power and which tomographic redshift binning configuration returns the maximum information to constrain the cosmological parameters. To perform such analyses, we create several realistic photo-z distributions based on the Euclid Flagship simulation and we use the Fisher forecast and the cosmological inference code, CosmoSIS, over the different configurations of the galaxy samples to determine the cosmological constraining power.
Universitat Autònoma de Barcelona. Programa de Doctorat en Física
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Bezanson, Rachel, David A. Wake, Gabriel B. Brammer, Pieter G. van Dokkum, Marijn Franx, Ivo Labbé, Joel Leja et al. "LEVERAGING 3D-HST GRISM REDSHIFTS TO QUANTIFY PHOTOMETRIC REDSHIFT PERFORMANCE". IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621218.

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We present a study of photometric redshift accuracy in the 3D-HST photometric catalogs, using 3D-HST grism redshifts to quantify and dissect trends in redshift accuracy for galaxies brighter than JH(IR) > 24 with an unprecedented and representative high-redshift galaxy sample. We find an average scatter of 0.0197 +/- 0.0003(1 + z) in the Skelton et al. photometric redshifts. Photometric redshift accuracy decreases with magnitude and redshift, but does not vary monotonically with color or stellar mass. The 1 sigma scatter lies between 0.01 and 0.03 (1 + z) for galaxies of all masses and colors below z. <. 2.5 (for JH(IR) < 24), with the exception of a population of very red (U - V > 2), dusty star-forming galaxies for which the scatter increases to similar to 0.1 (1+ z). We find that photometric redshifts depend significantly on galaxy size; the largest galaxies at fixed magnitude have photo-zs with up to similar to 30% more scatter and similar to 5 times the outlier rate. Although the overall photometric redshift accuracy for quiescent galaxies is better than that for star-forming galaxies, scatter depends more strongly on magnitude and redshift than on galaxy type. We verify these trends using the redshift distributions of close pairs and extend the analysis to fainter objects, where photometric redshift errors further increase to similar to 0.046 (1 + z) at H-F160W = 26. We demonstrate that photometric redshift accuracy is strongly filter dependent and quantify the contribution of multiple filter combinations. We evaluate the widths of redshift probability distribution functions and find that error estimates are underestimated by a factor of similar to 1.1 - 1.6, but that uniformly broadening the distribution does not adequately account for fitting outliers. Finally, we suggest possible applications of these data in planning for current and future surveys and simulate photometric redshift performance in the Large Synoptic Survey Telescope, Dark Energy Survey (DES), and combined DES and Vista Hemisphere surveys.
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Blake, R. Melvin. "Photometric decomposition of NGC 6166". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22790.pdf.

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Silva, Fernández Simón Yeco. "Photometric Redshifts in the HDFS". Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/133104.

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Magíster en Ciencias, Mención Astronomía
Se presenta fotometría óptica en 11 bandas medias a partir de observaciones realizadas con el telescopio de 2.2m en LSO (WFI) sobre un campo de ~30'×30' deg extendido en el Hubble Deep Field-South (EHDF-S), el cual es uno de los campos que contiene información en multibandas como parte del Multiwavelength Survey by Yale-Chile (MUSYC). Este campo tiene una gran cantidad de datos públicos y datos auxiliares en bandas UV, óptico, infrarrojo cercano e infrarrojo lejano. Se determinaron aperturas óptimas para fotometría de alta precisión para diversas fuentes y brillos. Se proporcionan incertezas en magnitud a través de una técnica mejorada que considera correlaciones a mayor y menor escala en el ruido. Se incluyen datos auxiliares en el óptico a partir del catálogo de MUSYC en bandas UBVRIz ' hasta una magnitud total de R=25 (AB), además de datos en infrarrojo cercano JHK de dos campos de 10 '× 10' deg con profundidades de J~22.5, H~21.5 y K~21 (5σ; Vega). Se creó un catálogo fotométrico de ~62.000 galaxias detectadas en la imagen BVR de MUSYC. Se miden redshifts fotométricos mediante el código EAzY y se compara con ~500 fuentes identificadas espectroscópicamente con la finalidad de probar la precisión y desempeño de los filtros en bandas medias. Los redshifts fotométricos resultaron más confiables para R<24 cuando la muestra contiene ~12.000 galaxias, particularmente en 0.1 < z < 1.2, región de sampleo en el óptico de características como el quiebre de Balmer. La precisión de los redshifts fotométricos en Δz/(1+z) es de 0.029, lo cual es comparable a estudios recientes con un mejoramiento del 20%. Estos valores se degradan en calidad para galaxias más débiles o cuando se utilizan menos bandas. Como demostración de la calidad de los resultados, se derivan tipos espectrales de las fuentes, luego se construyen funciones de luminosidad para comparar con trabajos similares, y así confirmar la fuerte dependencia de las SEDs con la densidad numérica de fuentes. Se incorporan datos observacionales en radio en el HDFS del Australia Telescopio Hubble Deep Field-South para estudiar en detalle su población. Este proyecto realizó observaciones en cuatro longitudes de onda, 20, 11, 6 y 3 cm y alcanza una sensibilidad en rms alrededor de 10 μJy para cada longitud de onda. Utilizando una muestra de 227 fuentes en radio seleccionadas, se realiza una clasificación detallada de la población en AGNs (-loud de radio (9%) y -quiet (46%)), galaxias con formación estelar (SFG; 39%), y galaxias normales (6%), usando los redshifts fotométricos, información en multibanda, un template combinado quasares, índices espectrales, las SEDs derivadas y la dependencia redshift luminosidad. Se confirman los resultados recientes sobre la disribución de AGNs y SFGs. Asimismo las LFs muestran consistencia para las fuentes en radio para z~1.0. Los resultados obtenidos siguen la tendencia de los trabajos previos de los últimos 4 a 5 años en la distribución de las fuentes de radio, y sugiere nuevas metodologías en torno a la caracterizacón la población en radio.
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7

Campisi, Andrea. "Development of a photometric stereo system". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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Abstract (sommario):
Photometric stereo is a method of estimating surface geometry by using a fixed-position camera and multiple light sources. The idea of photometric stereo is to vary the direction of incident illumination between successive images, while the viewing direction is constant; in this way, the correspondence of image points is known beforehand, as the position of the object is not changed, and surface orientation is determined by using the radiance values recorded with the different images. Photometric stereo has several applications: it is used to detect small surface defects, imperceptible to the human eye; it has also medical applications, i.e. to detect skin lesions and help in the diagnosis of melanoma. More recently, it has been used also to perform a non-invasive 3D scan of surfaces, and as a cheap method to get a real-time facial motion capture, widely used in computer graphics applications. The goals of this thesis are to describe the main algorithms used to achieve a photometric stereo analysis of surfaces, and the realization of a hardware device capable of acquire the images.
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Botzler, Christine S. "Finding Structures in Photometric Redshift Surveys". Diss., lmu, 2004. http://nbn-resolving.de/urn:nbn:de:bvb:19-22187.

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Buyukatalay, Soner. "Photometric Stereo Considering Highlights And Shadows". Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613749/index.pdf.

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Three dimensional (3D) shape reconstruction that aims to reconstruct 3D surface of objects using acquired images, is one of the main problems in computer vision. There are many applications of 3D shape reconstruction, from satellite imaging to material sciences, considering a continent on earth or microscopic surface properties of a material. One of these applications is the automated firearm identification that is an old, yet an unsolved problem in forensic science. Firearm evidence matching algorithms rely on the fact that a firearm creates characteristic marks on surfaces of the bullets and the cartridge cases. These marks should be digitized unaffected from different surface material properties of evidences. Accuracy of 3D shape is one of the most important parameters affecting the overall identification performance. A very high resolution, accurate 3D data have to be reconstructed in the order of minutes. Photometric stereo (PS) method is capable of reconstructing high resolution surfaces in a fast manner. But, the metallic material and the surface topology of the firearm evidences generate highlights and shadows on their images that does not comply with the assumptions of conventional PS. In the scope of this work, it is intended to design an accurate, fast and robust 3D shape reconstruction scheme using PS considering highlights and shadows. These new PS procedures to be developed here should not be limited only to the ballistic evidences but they also could be used for a wider range of objects reflection properties and texture. For this purpose, masked PS methods which are quite fast when compared to other approaches, were classified and implemented. Simple additional masking methods are also proposed. A novel weighted PS method, using weighted least square estimation, is presented to eliminate false edges created by the masks. Concurrently, the calibration processes and the illumination configuration were improved. The disturbances due to close light sources were removed by image calibrations. From experimental tests to simulate the light positioning problem, it is concluded that the double zenith illumination configuration have better performance than the optimal single zenith illumination configuration, when the highlights and the shadows are considered. Double zenith illumination configuration results were further improved by the weighted normal PS with a small additional computation cost. All the implemented methods were tested firstly on the controlled environment using synthetic images. Later the same tests were conducted on real objects with varying characteristics as well as the firearm evidences.
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Samaddar, Debasmita. "Photometric variability of three brown dwarfs". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.24 Mb., 65 p, 2006. http://proquest.umi.com/pqdlink?did=1075713471&Fmt=7&clientId=8331&RQT=309&VName=PQD.

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Libri sul tema "Photometric"

1

Ohno, Yoshihiro. Photometric calibrations. Gaithersburg, MD: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1997.

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2

Booker, Robert L. Photometric calibrations. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1992.

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3

A, McSparron Donald, e United States. National Bureau of Standards., a cura di. Photometric calibrations. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1987.

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4

Ohno, Yoshihiro. Photometric calibrations. Gaithersburg, MD: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1997.

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Ohno, Yoshihiro. Photometric calibrations. Gaithersburg, MD: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1997.

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6

Ohno, Yoshihiro. Photometric calibrations. [Gaithersburg, MD]: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1997.

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7

Booker, Robert L. NBS measurement services: Photometric calibrations. Washington, D.C: National Bureau of Standards, 1987.

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8

Durou, Jean-Denis, Maurizio Falcone, Yvain Quéau e Silvia Tozza, a cura di. Advances in Photometric 3D-Reconstruction. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51866-0.

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Endre, Upor. Photometric methods in inorganic trace analysis. Amsterdam: Elsevier, 1985.

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Lopez-Cruz, Omar. Photometric properties of low-redshift galaxy clusters. Toronto: Dept. of Astronomy, University of Toronto, 1997.

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Capitoli di libri sul tema "Photometric"

1

Weik, Martin H. "photometric". In Computer Science and Communications Dictionary, 1271. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_14004.

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Gooch, Jan W. "Photometric". In Encyclopedic Dictionary of Polymers, 534. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_8682.

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3

Basri, Ronen. "Photometric Stereo". In Computer Vision, 603–8. Boston, MA: Springer US, 2014. http://dx.doi.org/10.1007/978-0-387-31439-6_254.

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Zickler, Todd. "Photometric Invariants". In Computer Vision, 599–603. Boston, MA: Springer US, 2014. http://dx.doi.org/10.1007/978-0-387-31439-6_544.

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Robles-Kelly, Antonio, e Cong Phuoc Huynh. "Photometric Invariance". In Imaging Spectroscopy for Scene Analysis, 63–87. London: Springer London, 2013. http://dx.doi.org/10.1007/978-1-4471-4652-0_6.

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Ikeuchi, Katsushi, Yasuyuki Matsushita, Ryusuke Sagawa, Hiroshi Kawasaki, Yasuhiro Mukaigawa, Ryo Furukawa e Daisuke Miyazaki. "Photometric Stereo". In Active Lighting and Its Application for Computer Vision, 107–23. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-56577-0_5.

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Ikeuchi, Katsushi, Yasuyuki Matsushita, Ryusuke Sagawa, Hiroshi Kawasaki, Yasuhiro Mukaigawa, Ryo Furukawa e Daisuke Miyazaki. "Photometric Estimation". In Active Lighting and Its Application for Computer Vision, 183–209. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-56577-0_8.

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Sterken, Chr, e J. Manfroid. "Photometric systems". In Astrophysics and Space Science Library, 229–47. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2476-8_16.

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Sterken, Chr, e J. Manfroid. "Photometric filters". In Astrophysics and Space Science Library, 81–92. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2476-8_5.

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Zickler, Todd. "Photometric Invariants". In Computer Vision, 970–75. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63416-2_544.

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Atti di convegni sul tema "Photometric"

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Zwinkels, Joanne C. "Issues and Strategies for Improving Measurement Uncertainties for Solid-State Lighting". In NCSL International Workshop & Symposium. NCSL International, 2016. http://dx.doi.org/10.51843/wsproceedings.2016.23.

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The use of solid-state lighting (SSL), such as light-emitting-diode (LED) products for general lighting and display applications, has increased dramatically over the past decade. However, there are significant photometric and radiometric metrological challenges with this new lighting technology. The photometric procedures and standards that have been developed for traditional lighting products, such as incandescent and compact fluorescent (CFL) lamps, do not work well for LEDs because they exhibit significantly different characteristics. This paper will discuss these differences in the spectral, geometric and operating properties of LEDs and how they impact precise photometric measurements and associated performance metrics, such as color rendering index (CRI). The current state-of-the-art uncertainties for photometric measurements of LED lighting products is about a factor of 5 poorer than for traditional lamps, based upon the results of recent interlaboratory comparisons involving both national measurement institutes (NMIs) and accredited laboratories. Reducing the uncertainty of these measurements will have a significant impact on society - both on reducing costs due to energy savings, but also on improving overall lighting quality and performance. For these reasons, there are a number of activities being carried out both at the national and international level to address these LED measurement issues. This paper will highlight the current strategies and standardization activities within both the Consultative Committee of Photometry and Radiometry (CCPR) and the International Commission of Illumination (CIE) to develop improved measurement techniques, transfer standards and metrics for the measurement and use of LED lighting in photometry and to meet consumer needs.
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Haefner, Bjoern, Yvain Queau e Daniel Cremers. "Photometric Segmentation: Simultaneous Photometric Stereo and Masking". In 2019 International Conference on 3D Vision (3DV). IEEE, 2019. http://dx.doi.org/10.1109/3dv.2019.00033.

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Popescu, Nedelia A. "Photometric redshifts determinations for galaxies by means of multicolor photometry". In FIFTY YEARS OF ROMANIAN ASTROPHYSICS. AIP, 2007. http://dx.doi.org/10.1063/1.2720449.

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Hauagge, Daniel, Scott Wehrwein, Kavita Bala e Noah Snavely. "Photometric Ambient Occlusion". In 2013 IEEE Conference on Computer Vision and Pattern Recognition (CVPR). IEEE, 2013. http://dx.doi.org/10.1109/cvpr.2013.325.

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Lap-Fai Yu, Sai-Kit Yeung, Yu-Wing Tai, D. Terzopoulos e T. F. Chan. "Outdoor photometric stereo". In 2013 IEEE International Conference on Computational Photography (ICCP). IEEE, 2013. http://dx.doi.org/10.1109/iccphot.2013.6528306.

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Du, Hao, Dan Goldman e Steven Seitz. "Binocular Photometric Stereo". In British Machine Vision Conference 2011. British Machine Vision Association, 2011. http://dx.doi.org/10.5244/c.25.84.

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Draper, R. J. "Reflective photometric stereo". In 6th International Conference on Image Processing and its Applications. IEE, 1997. http://dx.doi.org/10.1049/cp:19970926.

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Olczak, Paul, e Jack Tumblin. "Photometric camera calibration". In ACM SIGGRAPH 2014 Posters. New York, New York, USA: ACM Press, 2014. http://dx.doi.org/10.1145/2614217.2614244.

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Higo, Tomoaki, Yasuyuki Matsushita e Katsushi Ikeuchi. "Consensus photometric stereo". In 2010 IEEE Conference on Computer Vision and Pattern Recognition (CVPR). IEEE, 2010. http://dx.doi.org/10.1109/cvpr.2010.5540084.

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Calef, Brandoch, John Africano, Brian Birge, Doyle Hall e Paul Kervin. "Photometric signature inversion". In SPIE Optics + Photonics, a cura di Victor L. Gamiz, Paul S. Idell e Marija S. Strojnik. SPIE, 2006. http://dx.doi.org/10.1117/12.683015.

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Rapporti di organizzazioni sul tema "Photometric"

1

Ohno, Yoshihiro. Photometric calibrations. Gaithersburg, MD: National Institute of Standards and Technology, 1997. http://dx.doi.org/10.6028/nist.sp.250-37.

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2

Booker, Robert L., e Donald A. McSparron. Photometric calibrations. Gaithersburg, MD: National Bureau of Standards, 1987. http://dx.doi.org/10.6028/nbs.sp.250-15.

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Perrin, TE, CC Brown, ME Poplawski e NJ Miller. Characterizing Photometric Flicker. Office of Scientific and Technical Information (OSTI), febbraio 2017. http://dx.doi.org/10.2172/1607663.

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Zong, Yuqin, Maria E. Nadal, Benjamin K. Tsai e C. Cameron Miller. NIST measurement services: photometric calibrations. Gaithersburg, MD: National Institute of Standards and Technology, luglio 2018. http://dx.doi.org/10.6028/nist.sp.250-95.

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Leon, Felipe A., Joshua A. McIntosh, Addison J. Rutz, Naomi J. Miller e Michael P. Royer. Characterizing Photometric Flicker - Handheld Meters. Office of Scientific and Technical Information (OSTI), febbraio 2019. http://dx.doi.org/10.2172/1567860.

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Kent, Stephen, Mary Elizabeth Kaiser, Susana E. Deustua, J. Allyn Smith, Saul Adelman, Sahar S. Allam, Brian Baptista et al. Photometric calibrations for 21st century science. Office of Scientific and Technical Information (OSTI), febbraio 2009. http://dx.doi.org/10.2172/951353.

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Landolt, Arlo. Faint Photoelectric Photometric Standard Star Sequences. Fort Belvoir, VA: Defense Technical Information Center, luglio 1988. http://dx.doi.org/10.21236/ada201999.

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May, M. J. Photometric Calibration of the SPRED at the FTU Tokamak. Office of Scientific and Technical Information (OSTI), dicembre 1999. http://dx.doi.org/10.2172/15004653.

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Carrasco Kind, Matias. Probabilistic Photometric Redshifts in the Era of Petascale Astronomy. Office of Scientific and Technical Information (OSTI), gennaio 2014. http://dx.doi.org/10.2172/1172583.

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Ortiz, M. Growing Self-Organizing Maps as Predictors for Photometric Redshift. Office of Scientific and Technical Information (OSTI), agosto 2019. http://dx.doi.org/10.2172/1557954.

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