Local Cues for Half-Occlusion Detection in Stereo-Images of Natural Scenes

ABSTRACTLocal depth variation is a distinctive property of natural scenes and its effects on perception have only recently begun to be investigated. Here, we demonstrate how natural depth variation impacts performance in two fundamental tasks related to stereopsis: half-occlusion detection and disparity detection. We report the results of a computational study that uses a large database of calibrated natural stereo-images with precisely co-registered laser-based distance measurements. First, we develop a procedure for precisely sampling stereo-image patches from the stereo-images, based on the distance measurements. The local depth variation in each stereo-image patch is quantified by disparity contrast. Next, we show that increased disparity contrast degrades performance in half-occlusion detection and disparity detection tasks, and changes the size and shape of the optimal spatial integration areas (“receptive fields”) for computing the task-relevant decision variables. Then, we show that a simple binocular image statistic predicts disparity contrast in natural scenes. Finally, we report results on the most likely patterns of disparity variation in natural scenes. Our findings motivate computational and psychophysical investigations of the mechanisms that underlie disparity estimation in local regions of natural scenes.

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Optimal disparity estimation in stereo-images of natural scenes

Journal of Vision ◽

10.1167/11.11.295 ◽

2011 ◽

Vol 11 (11) ◽

pp. 295-295

Author(s):

J. Burge ◽

W. Geisler

Keyword(s):

Disparity Estimation ◽

Natural Scenes ◽

Stereo Images

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Stereo imaging in the shadow electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107745 ◽

1978 ◽

Vol 36 (1) ◽

pp. 120-121

Author(s):

W. C. T. Dowell

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Convenient Method ◽

Patent Application ◽

Standard Technique ◽

Stereo Imaging ◽

Stereo Images ◽

Specimen Height

Stereo imaging is not new to electron microscopy. Von Ardenne, who first published transmission pairs nearly forty hears ago, himself refers to a patent application by Ruska in 1934. In the early days of the electron microscope von Ardenne employed a pair of magnetic lenses to view untilted specimens but soon opted for the now standard technique of tilting the specimen with respect to the beam.In the shadow electron microscope stereo images can, of course, be obtained by tilting the specimen between micrographs. This obvious method suffers from the disadvantage that the magnification is very sensitive to small changes in specimen height which accompany tilting in the less sophisticated stages and it is also time consuming. A more convenient method is provided by horizontally displacing the specimen between micrographs. The specimen is not tilted and the technique is both simple and rapid, stereo pairs being obtained in less than thirty seconds.

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