Camera Calibration Method for Far Range Stereovision Sensors Used in Vehicles

Towards the Influence of a Car Windshield on Depth Calculation With a Stereo Camera System

“…As most critical and sensitive camera parameters of a stereo camera system, the relative orientation is identified (Marita et al, 2006). A drift of only a few seconds in the relative angle between the two cameras will lead to a lack of reconstructed 3d points.…”

Calibration and Sensitivity Analysis of a Stereo Vision-Based Driver Assistance System

“…A rough pose estimation can be performed by first estimating the homography between the world plane and the image and then by re-using the orthogonality constraints with known camera calibration matrix K (Malm & Heyden, 2003;Lepetit & Fua, 2005). The planar pattern used in intrinsic calibration is unsuitable for far-range systems, because it minimizes errors for close-range (as also stated in Marita et al, 2006;Bellino et al, 2005). For this purpose, Broggi et al used a medium-range grid painted on the ground (Broggi et al, 2005) while Marita et al used vertical X-shaped markers placed on the ground in front of the vehicle in a distance up to 45 m (Marita et al, 2006).…”

“…The planar pattern used in intrinsic calibration is unsuitable for far-range systems, because it minimizes errors for close-range (as also stated in Marita et al, 2006;Bellino et al, 2005). For this purpose, Broggi et al used a medium-range grid painted on the ground (Broggi et al, 2005) while Marita et al used vertical X-shaped markers placed on the ground in front of the vehicle in a distance up to 45 m (Marita et al, 2006). In the latter work, the intrinsic and the extrinsic parameters of each camera are computed separately.…”

“…The localization is achieved through the 3D reconstruction of the lane's geometry from the acquired images. In monocular lane detection systems, reconstruction usually relies on a number of assumptions concerning the scene geometry and the vehicle motion, such as flat road and constant pitch and roll angles, which are not always valid (as also stated in Kastrinaki et al, 2003;Marita et al, 2006). Stereo vision provides an effective and reliable means to extract correct range information without the need of relying on doubtful assumptions (Hartley & Zisserman, 2006).…”

“…IPM techiques (and also the one based on the Helmholtz shear equation) may fail when the relative orientations of cameras with respect to the road's plane are not precisely determined (Weber et al, 1995;Broggi et al, 2001). Since epipolar lines and the rays at the triangulation step are highly dependent on the camera parameters, both stereo matching and 3D reconstruction may prove unsatisfactory (Marita et al, 2006). These facts highlight the importance of an accurate calibration and motivate a thorough sensitivity analysis in the design of such safety-critical systems.…”