Structure from Infrared Stereo Images

Discovering depth from stereopsis is difficult because the quality of un-cooled sensors is not sufficient for generating dense depth maps. We show how to produce sparse disparity maps from uncalibrated infrared stereo images which can be interpolated to produce a dense/semi-dense depth field. In our proposed technique, the sparse disparity map is produced by a robust features-based stereo matching method capable of dealing with the problems of infrared images, such as low resolution and high noise. Initially, a set of stable features are extracted from stereo pairs using the phase congruency model, which contrary to the gradient-based feature detectors, provides features that are invariant to geometric transformations. Then, a set of log-Gabor wavelet coefficients at different orientations and frequencies is used to analyze and describe the extracted features for matching. The resulting sparse disparity map is then refined by triangular and epipolar geometrical constraints. In densifying the sparse map, a watershed transformation is applied to divide the image into several segments, where the disparity inside each segment is assumed to vary smoothly. The surface of each segment is then reconstructed independently by fitting a spline to its known disparities. Results indicate strong correlation with ground truth. The marginal results from the watershed segmentation on IR is chiefly responsible for the errors in the reconstructed depth map.