Tremblay G.,AEREX Avionics Inc. |
Cao X.,Royal Military College of Canada |
Roy G.,DRDC Valcartier
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
A laser pulse propagating through dense clouds suffers from spatial and temporal distortion caused by multiple scattering of light. Both distortions are function of the optical depth, the particle size of the aerosols and the cloud distance relative to the target and receiver. In order to study the effects of all theses parameters, 3-D Monte-Carlo (MC) simulations were performed. The Monte Carlo developed for this purpose has the unique capability to produce both 2D and 3D images of the scenes. For the 2D images we calculated the Modulation Transfer Function (MTF) using the Fourier transform of the system Point Spread function (PSF). For the 3D images, gratings with rectangular grooves of various frequencies and heights were used and the concept of contrast applied as for the calculation of MTF for 2D images. We found that 3D temporal distortion effects are significantly reduced when the reconnaissance algorithm is based on the shape of the raising pulse. © 2010 SPIE.
Boudreau S.,Laval University |
Levasseur S.,Laval University |
Perilla C.,Laval University |
Roy S.,DRDC Valcartier |
Genest J.,Laval University
Optics Express | Year: 2013
High-resolution spectral lidar measurements using dual frequency combs as a source is presented. The technique enables the rangeresolved measurement of fine spectral features, such as gas absorption lines, provided that a suitable scatterer is present in the scene. Measurements of HCN absorption lines at 20 meters are presented, with a water droplet cloud and a diffusely reflective surface as scatterers. © 2013 Optical Society of America.
Hamel N.,DRDC Valcartier |
Gagnon E.,DRDC Valcartier
29th AIAA Applied Aerodynamics Conference 2011 | Year: 2011
Guided artillery projectiles will offer substantial improvement in the accurate delivery of effects on target. A number of projects are under way in several countries with the objective to develop and field precision guided artillery munitions. A study of the aerodynamic characteristics as well as a Monte Carlo parametric analysis were carried out on a 155 mm shell concept equipped with a four-canard roll-decoupled course correction fuze. The course correction fuze concept studied is shown to efficiently counteract the gun azimuth and elevation perturbations. It can also correct the muzzle velocity perturbations when particular launch conditions are met, but it has a minimal effect on correcting the wind perturbations. The best accuracy results are obtained at low gun elevation, high muzzle velocity and short guidance lock delay. © 2011 by The Government of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc.
Lahaie P.,DRDC Valcartier
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014
The atmospheric correction of thermal hyperspectral imagery can be separated in two distinct processes: Atmospheric Compensation (AC) and Temperature and Emissivity separation (TES). TES requires for input at each pixel, the ground leaving radiance and the atmospheric downwelling irradiance, which are the outputs of the AC process. The extraction from imagery of the downwelling irradiance requires assumptions about some of the pixels' nature, the sensor and the atmosphere. Another difficulty is that, often the sensor's spectral response is not well characterized. To deal with this unknown, we defined a spectral mean operator that is used to filter the ground leaving radiance and a computation of the downwelling irradiance from MODTRAN. A user will select a number of pixels in the image for which the emissivity is assumed to be known. The emissivity of these pixels is assumed to be smooth and that the only spectrally fast varying variable in the downwelling irradiance. Using these assumptions we built an algorithm to estimate the downwelling irradiance. The algorithm is used on all the selected pixels. The estimated irradiance is the average on the spectral channels of the resulting computation. The algorithm performs well in simulation and results are shown for errors in the assumed emissivity and for errors in the atmospheric profiles. The sensor noise influences mainly the required number of pixels. © 2014 SPIE.
Ross V.,AEREX Avionique Inc. |
Dion D.,DRDC Valcartier
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011
A new C++ library for radiative transfer calculations in the visible and infrared bands which uses MODTRAN as a primary source for atmospheric optical parameters has been developed at Defense R&D Canada, Valcartier (DRDC Valcartier). The main benefit of the library is its capability to perform fast wide spectral band calculations with an appreciably high accuracy. Coherent calculations on wide bands are made possible by using a modified version of the correlated-k theory. The main features of the library are discussed, and comparisons with conventional spectral MODTRAN 4 calculations are presented. It is shown that the library is capable of producing band results that are usually within 5% of MODTRAN 4 with computation times that are thousands of times faster. © 2011 SPIE.
Roy G.,DRDC Valcartier |
Roy S.,DRDC Valcartier
Annual Forum Proceedings - AHS International | Year: 2014
In support to the Directorate of Technical Airworthiness and Engineering Support (DTAES-6) of Canada's Department of National Defence (DND), DRDC Valcartier is currently evaluating the Obscurant Penetrating Autosynchronous Lidar (OPAL) developed by Neptec Technologies Corp. This sensor is targeted at supporting rotary-wing aircraft operating in degraded visual environments (DVE) during critical flight phases (i.e. take-off and landing). OPAL consists of a scanning pulsed lidar that generates 3D images of obstacles on the landing zone that are engulfed in an obscurant cloud. The sensor performance evaluation study is conducted in three phases under the MATPILA project (Multipurpose airborne 3D polarimetric imaging ladar assessment). Phase I focused on acquiring knowledge on brownout and whiteout phénoménologies and on defining proper testing conditions and performance metrics for Phase H. Phase II aimed at quantifying the sensor see-through capability as a function of optical depth and target reflectivity. Phase III consisted of in-flight validation trials. This paper presents Phase I to III with an emphasis on control environment test and on the in-flight validation trials. Copyright© 2014 by the American Helicopter Society International, Inc. All rights reserved.
Kapp M.N.,École de Technologie Supérieure of Montreal |
Sabourin R.,École de Technologie Supérieure of Montreal |
Maupin P.,DRDC Valcartier
Proceedings - International Conference on Pattern Recognition | Year: 2010
The incremental updating of classifiers implies that their internal parameter values can vary according to incoming data. As a result, in order to achieve high performance, incremental learner systems should not only consider the integration of knowledge from new data, but also maintain an optimum set of parameters. In this paper, we propose an approach for performing incremental learning in an adaptive fashion with an ensemble of support vector machines. The key idea is to track, evolve, and combine optimum hypotheses over time, based on dynamic optimization processes and ensemble selection. From experimental results, we demonstrate that the proposed strategy is promising, since it outperforms a single classifier variant of the proposed approach and other classification methods often used for incremental learning. © 2010 IEEE.
Lahaie P.,DRDC Valcartier |
Simard J.-R.,DRDC Valcartier |
Buteau S.,DRDC Valcartier
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
Photon counting technologies are developed and could be used in the future to measure the return from laser induced fluorescence. Currently, the spectral detection of light emitted by fluorescing aerosols is performed with ICCD, Intensified Charge Coupled Device. The signal to noise ratio of ICCD devices is smaller by a factor of 2compared to photon counting devices having the same sensitivity. We studied the impact of this difference of signal to noise ratio on the capability of multivariate detection and classification algorithms to operate on various conditions. Signal simulations have been performed to obtain ROC (Receiver Operation Characteristics) Curves and Confusion Matrix to obtain the detection performance and the ability of algorithms to discriminate a potential source from another. Two detection algorithms are used, the Integrated Laser Induced Fluorescence(ILIF) and the Matched Filter. For the classification, three algorithms are used, the Adaptive Matched Filter (AMF), the Adaptive Coherent Estimator (ACE) and the Adaptive Least Squares (ALS). The best algorithm for detection is the AMF using the signature of the material present in a cloud, the ILIF detector performs very well. For the classification, the three algorithms are surprisingly giving the same results for the same data. The classification performs better if the distance between the signatures recorded in a database is important. The performance of the detector and of the classificator improves with an increase of the signal to noise ratio and is consistently and significantly better for the photon counting compared to ICCD. © 2013 SPIE.
Berger J.,DRDC Valcartier |
Lo N.,T OptLogic Ltd.
Computers and Operations Research | Year: 2015
Search and rescue path planning is known to be computationally hard, and most techniques developed to solve practical size problems have been unsuccessful to estimate an optimality gap. A mixed-integer linear programming (MIP) formulation is proposed to optimally solve the multi-agent discrete search and rescue (SAR) path planning problem, maximizing cumulative probability of success in detecting a target. It extends a single agent decision model to a multi-agent setting capturing anticipated feedback information resulting from possible observation outcomes during projected path execution while expanding possible agent actions to all possible neighboring move directions, considerably augmenting computational complexity. A network representation is further exploited to alleviate problem modeling, constraint specification, and speed-up computation. The proposed MIP approach uses CPLEX problem-solving technology in promptly providing near-optimal solutions for realistic problems, while offering a robust upper bound derived from Lagrangean integrality constraint relaxation. Modeling extension to a closed-loop environment to incorporate real-time action outcomes over a receding time horizon can even be envisioned given acceptable run-time performance. A generalized parameter-driven objective function is then proposed and discussed to suitably define a variety of user-defined objectives. Computational results reporting the performance of the approach clearly show its value. © 2014 Published by Elsevier Ltd. All rights reserved.
Lahaie P.,DRDC Valcartier |
Levesque J.,DRDC Valcartier
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2015
The processing chain leading to specific material detection in hyperspectral imagery implies the use of atmospherically corrected images of emissivity or reflectance before comparing image signatures to a database of materials' signatures. This is a sensible approach for the reflective hyperspectral bands l and when the pixels are completely filled with a uniform material in the LWIR bands (8 to 12 microns). In the LWIR, the atmospheric correction process is different of what is used in the reflective bands and involves the use of a temperature and emissivity separation process (TES). If the pixel is not filled with a uniform material and the measured radiance is produced from the mix of materials having different emissivity and temperatures, the output of the TES will not be linear in temperature and in emissivity and will be contaminated by the non-linear mix of the temperature and emissivity of the materials leading to a potential for confusion during the detection process. In this paper, we propose a detection approach using the ground leaving radiance that is used directly to perform detection using emissivity signatures contained in a database. The detection results using this process are compared with the detection results using the output of a TES algorithm. The study is performed in simulation without noise and with the exact knowledge of the downwelling irradiance. The results show that a detection algorithm using the ground leaving radiance performs better than its counterpart using the emissivity when the difference in temperature increases. © 2015 IEEE.