The Experts below are selected from a list of 25062 Experts worldwide ranked by ideXlab platform
Luc Van Gool - One of the best experts on this subject based on the ideXlab platform.
-
modeling the effects of windshield refraction for Camera calibration
European Conference on Computer Vision, 2020Co-Authors: Frank Verbiest, Marc Proesmans, Luc Van GoolAbstract:In this paper, we study the effects of windshield refraction for autonomous driving applications. These distortion effects are surprisingly large and can not be explained by Traditional Camera models. Instead of using a generalized Camera approach, we propose a novel approach to jointly optimize a Traditional Camera model, and a mathematical representation of the windshield’s surface. First, using the laws of geometric optics, the refraction is modeled using a local spherical approximation to the windshield’s geometry. Next, a spline-based model is proposed as a refinement to better adapt to deviations from the ideal shape and manufacturing variations. By jointly optimizing refraction and Camera parameters, the projection error can be significantly reduced. The proposed models are validated on real windshield observations and custom setups to compare recordings with and without windshield, with accurate laser scan measurements as 3D ground truth.
Hansgerd Maas - One of the best experts on this subject based on the ideXlab platform.
-
sensor modelling and Camera calibration for close range photogrammetry
Isprs Journal of Photogrammetry and Remote Sensing, 2016Co-Authors: Thomas Luhmann, Clive S Fraser, Hansgerd MaasAbstract:Abstract Metric calibration is a critical prerequisite to the application of modern, mostly consumer-grade digital Cameras for close-range photogrammetric measurement. This paper reviews aspects of sensor modelling and photogrammetric calibration, with attention being focussed on techniques of automated self-calibration. Following an initial overview of the history and the state of the art, selected topics of current interest within calibration for close-range photogrammetry are addressed. These include sensor modelling, with standard, extended and generic calibration models being summarised, along with non-Traditional Camera systems. Self-calibration via both targeted planar arrays and targetless scenes amenable to SfM-based exterior orientation are then discussed, after which aspects of calibration and measurement accuracy are covered. Whereas Camera self-calibration is largely a mature technology, there is always scope for additional research to enhance the models and processes employed with the many Camera systems nowadays utilised in close-range photogrammetry.
Shan Chen - One of the best experts on this subject based on the ideXlab platform.
-
transient full field vibration measurement using spectroscopical stereo photogrammetry
Optics Express, 2010Co-Authors: Kaiduan Yue, Ming Zhang, Shan ChenAbstract:Contrasted with other vibration measurement methods, a novel spectroscopical photogrammetric approach is proposed. Two colored light filters and a CCD color Camera are used to achieve the function of two Traditional Cameras. Then a new calibration method is presented. It focuses on the vibrating object rather than the Camera and has the advantage of more accuracy than Traditional Camera calibration. The test results have shown an accuracy of 0.02 mm.
Frank Verbiest - One of the best experts on this subject based on the ideXlab platform.
-
modeling the effects of windshield refraction for Camera calibration
European Conference on Computer Vision, 2020Co-Authors: Frank Verbiest, Marc Proesmans, Luc Van GoolAbstract:In this paper, we study the effects of windshield refraction for autonomous driving applications. These distortion effects are surprisingly large and can not be explained by Traditional Camera models. Instead of using a generalized Camera approach, we propose a novel approach to jointly optimize a Traditional Camera model, and a mathematical representation of the windshield’s surface. First, using the laws of geometric optics, the refraction is modeled using a local spherical approximation to the windshield’s geometry. Next, a spline-based model is proposed as a refinement to better adapt to deviations from the ideal shape and manufacturing variations. By jointly optimizing refraction and Camera parameters, the projection error can be significantly reduced. The proposed models are validated on real windshield observations and custom setups to compare recordings with and without windshield, with accurate laser scan measurements as 3D ground truth.
H C Silva - One of the best experts on this subject based on the ideXlab platform.
-
identification of a scaled model riser dynamics through a combined computer vision and adaptive kalman filter approach
Mechanical Systems and Signal Processing, 2014Co-Authors: Flavio Celso Trigo, Flavius Portella Ribas Martins, Agenor De Toledo Fleury, H C SilvaAbstract:Abstract Aiming at overcoming the difficulties derived from the Traditional Camera calibration methods to record the underwater environment of a towing tank where experiments of scaled-model risers are carried on, a computer vision method, combining Traditional image processing algorithms and a self-calibration technique was implemented. This method was used to identify the coordinates of control-points viewed on a scaled-model riser submitted to a periodic force applied to its fairlead attachment point. To study the observed motion, the riser was represented as a pseudo-rigid body model (PRBM) and the hypotheses of compliant mechanisms theory were assumed in order to cope with its elastic behavior. The derived Lagrangian equations of motion were linearized and expressed as a state-space model in which the state variables include the generalized coordinates and the unknown generalized forces. The state-vector thus assembled is estimated through a Kalman Filter. The estimation procedure allows the determination of both the generalized forces and the tension along the cable, with statistically proven convergence.