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13. Toward standardized testing of automotive lidars: year two results.

Author

Aspiras, Theus H., Asari, Vijayan K., Bradley, Cullen, Gnacek, Anna, Kershner, Charlie, LeMaster, Daniel A., McManamon, Paul F., Reinhardt, Andrew D., Ruff, Eddie, Valenta, Christopher R., and Van Rynbach, Andre

Subjects
DRIVER assistance systems, SOLAR radiation, TRAFFIC signs & signals, UNITS of measurement, SAFETY standards
Abstract

SPIE is working with SAE International to develop lidar measurement standards for active safety systems. This multi-year effort aims to develop standard tests to measure the performance of low-cost lidar sensors developed for autonomous vehicles or advanced driver assistance systems, commonly referred to as automotive lidars. SPIE is sponsoring three years of testing to support this goal. We discuss the second-year test results. In year two, we tested nine models of automotive grade lidars, using child-size targets at short ranges and larger targets at longer ranges. We also tested the effect of high reflectivity signs near the targets, laser safety, and atmospheric effects. We observed large point densities and noise dependencies for different types of automotive lidars based on their scanning patterns and fields of view. In addition to measuring point density at a given range, we have begun to evaluate the point density in the presence of measurement impediments, such as atmospheric absorption or scattering and highly reflective corner cubes. We saw dynamic range effects in which bright objects, such as road signs with corner cubes embedded in the paint, make it difficult to detect low-reflectivity targets that are close to the high-reflectivity target. Furthermore, preliminary testing showed that atmospheric extinction in a water-glycol fog chamber is comparable to natural fog conditions at ranges that are meaningful for automotive lidar, but additional characterization is required before determining general applicability. This testing also showed that laser propagation through water-glycol fog results in appreciable backscatter, which is often ignored in automotive lidar modeling. In year two, we have begun to measure the effect of impediments to measuring the 3D point cloud density; these measurements will be expanded in year three to include interference with other lidars. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Data collection and preliminary results on turbulence characterisation and mitigation techniques

Author

Velluet, Marie-Thérèse, Bell, Christopher, Daigle, Jean-François, Dijk, Judith, Gladysz, Szymon, Kanaev, Andrey, Lambert, Andrew, Lemaster, Daniel, Potvin, Guy, Vorontsov, Mikhail, DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Université Paris Saclay (COmUE), Dstl Fort Halsyead, Defense Research and Development Canada, Valcartier (DRDC), The Netherlands Organisation for Applied Scientific Research (TNO), Fraunhofer Institute of Optronics, System Technologies and Image Exploitation (Fraunhofer IOSB), Fraunhofer (Fraunhofer-Gesellschaft), Naval Research Laboratory (NRL), University of New South Wales [Canberra Campus] (UNSW), Air Force Research Laboratory (AFRL), United States Air Force (USAF), and University of Dayton

Subjects
ADAPTIVE OPTICS, [PHYS]Physics [physics], IMAGE PROCESSING, TURBULENCE OPTIQUE, PROPAGATION, PROPAGATION LASER, OPTIQUE ADAPTATIVE, [SPI]Engineering Sciences [physics], TRAITEMENT IMAGE, EXPERIMENTS, TURBULENCE, LASER BEAM DELIVERY, EXPERIMENTATION, PROPAGATION OPTIQUE
Abstract

International audience; In the framework of NATO task group SET 226 on turbulence mitigation techniques for OA systems, a trial was conducted in the premises of RDDC-Valcartier, using indoor and outdoor facilities in September 2016. Images data sets were collected under various turbulence conditions, both controllable (indoor) and natural (outdoor). The imagery of this trial was used in the Grand Challenge, where different experts were asked to process identical input data with state-of-the-art algorithms. The trial also provided a database to validate theoretical and numerical models. The paper will give an overview of the experiment setup (target, sensors, turbulence screens generators…) and present some preliminary results obtained with the collected data in terms of effectiveness of image processing techniques, new methods for turbulence characterisation, modelling of laser beam propagation.; Augmenter la distance et/ou la résolution des systèmes optiques et laser devient de plus en plus difficile. La turbulence présente entre la cible et le senseur ou la source dégrade les performance des systèmes imageurs, des communications laser en espace libre, les systèmes de focalisation laser ou les armes à énergie dirigée. Des techniques permettant de réduire les effets induits pas la turbulence peuvent être utilisées. L'optique adaptative (OA) est plus efficaces pour des systèmes laser, tandis que le traitement du signal est plus approprié pour les systèmes imageurs. Cependant, plus la turbulence est importante moins ces techniques sont efficaces. Comprendre la turbulence et ses effets à travers des modèles et des simulations permet de développer des instruments et des algorithmes pour la mesurer et réduire ses effets. Dans le cadre du groupe OTAN SET 226 sur les techniques de mitigation de la turbulence pour les systèmes optiques, une expérimentation a été réalisée dans les locaux du RDDC Valcatier (Canada), en septembre 2016 en utilisant les équipements intérieurs et extérieurs. 8 nations ont été impliquées dans cette expérimentation. Des séquences d'images ont été enregistrées sous différentes conditions de turbulence, en environnement contrôlable (intérieur) et naturel (extérieur). Les images ont été utilisé dans le "Grand Challenge", pour lequel plusieurs experts ont mis en œuvre des algorithmes à l'état-de-l'art pour restaurer les images. Des données ont également été enregistrées pour valider les méthodes théoriques et numériques. Une autre sortie du groupe est la mise en œuvre d'instruments pour caractériser la turbulence ainsi que leur comparaison.Ce papier présente l'expérimentation (cibles, senseurs, écrans générateurs de turbulence...) et donne quelques résultats préliminaires obtenues avec les données collectées pour ce qui est de l'efficacité des techniques de traitement d'images, des méthodes de caractérisation de la turbulence, de la modélisation de la propagation laser.

Published
2019
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31. Polarization Aberration in Astronomical Telescopes

Author

Shaw, Joseph A., LeMaster, Daniel A., Chipman, Russell A., Lam, Wai Sze Tiffany, Breckinridge, James, Shaw, Joseph A., LeMaster, Daniel A., Chipman, Russell A., Lam, Wai Sze Tiffany, and Breckinridge, James

Abstract

The point spread function (PSF) for astronomical telescopes and instruments depends not only on geometric aberrations and scalar wave diffraction, but also on the apodization and wavefront errors introduced by coatings on reflecting and transmitting surfaces within the optical system. The functional form of these aberrations, called polarization aberrations, result from the angles of incidence and the variations of the coatings as a function of angle. These coatings induce small modifications to the PSF, which consists of four separate components, two nearly Airy-disk PSF components, and two faint components, we call ghost PSF components, with a spatial extent about twice the size of the diffraction limited image. As the specifications of optical systems constantly improve, these small effects become increasingly important. It is shown how the magnitude of these ghost PSF components, at ~10^(-5) in the example telescope, can interfere with exoplanet detection with coronagraphs.

Published
2015

40. Statistical Processing Methods for Polarimetric Imagery

Author

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT, LeMaster, Daniel A., AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT, and LeMaster, Daniel A.

Abstract

Estimation theory is applied to a physical model of incoherent polarized light to address problems in polarimetric image registration, restoration, and analysis for electro-optical imaging systems. In the image registration case, the Cramer-Rao lower bound on unbiased joint estimates of the registration parameters and the underlying scene is derived, simplified using matrix methods, and used to explain the behavior of multi-channel linear polarimetric imagers. In the image restoration case, a polarimetric maximum likelihood blind deconvolution algorithm is derived and tested using laboratory and simulated imagery. Finally, a principal components analysis is derived for polarization imaging systems. This analysis expands upon existing research by including an allowance for partially polarized and unpolarized light.

Published
2008

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