The Effects of Terrain and Observation Distance on Relative Depth Discrimination

1955 ◽  
Vol 68 (2) ◽  
pp. 193 ◽  
Author(s):  
Warren H. Teichner ◽  
John L. Kobrick ◽  
Robert F. Wehrkamp
Keyword(s):  
Relative Depth ◽  
Observation Distance ◽  
Depth Discrimination

Depth Discrimination from Optic Flow

Perception ◽  
1988 ◽  
Vol 17 (4) ◽  
pp. 497-512 ◽  
Author(s):  
William A Simpson
Keyword(s):  
Optic Flow ◽  
Depth Information ◽  
Relative Depth ◽  
Rotational Flow ◽  
Rotational Component ◽  
Threshold Elevation ◽  
Simple Scheme ◽  
Time To Collision ◽  
Depth Discrimination ◽  
Prior Adaptation

A simple scheme for deriving relative depth (time-to-collision, or TTC) from optic flow is developed in which the total flow is first sensed by unconnected motion (imperfect filter) sensors and then the rotational component is subtracted to yield the translational component. Only the latter component yields depth information. This scheme is contrasted with one where the TTC sensors respond only to the translational component at the initial registration of the flow (perfect filter sensors or looming detectors). The simple scheme predicts the results of three experiments on discrimination of TTC: discrimination thresholds are elevated if the objects withdraw from rather than approach the observer, thresholds are elevated if a rotational component is added to the flow, and the amount of threshold elevation resulting from the addition of a rotational component is reduced by prior adaptation to a pure rotational flow. These results confirm the simple model and disconfirm predictions based on the looming detector scheme.

Acquisition of Depth Discrimination in a Japanese Macaque: A Preliminary Study

1981 ◽  
Vol 52 (3) ◽  
pp. 827-830 ◽  
Author(s):  
Ken'Ichi Fuji ◽  
Shozo Kojima
Keyword(s):  
Japanese Monkey ◽  
Japanese Macaque ◽  
Training Method ◽  
Observation Distance ◽  
Tracking Method ◽  
Depth Discrimination ◽  
Preliminary Study ◽  
Difference Thresholds ◽  
Type Apparatus

A training method of depth discrimination in a Japanese monkey was reported. Using a Howard-Dohlman type apparatus, the monkey was required to discriminate the distance of two rods. Observation distance was 785 mm and a tracking method was employed. Difference thresholds measured preliminarily were 23.6 mm and 77.1 mm for binocular and monocular conditions, respectively.

Convex Grouping Impedes Detection of Stereoscopic Depth

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 242-242
Author(s):  
Z Liu
Keyword(s):  
Perceptual Grouping ◽  
Image Plane ◽  
Stereoscopic Depth ◽  
Relative Depth ◽  
Objective Method ◽  
Good Continuation ◽  
Depth Discrimination ◽  
Ground Segmentation ◽  
Planar Regions ◽  
Oval Shape

When two image regions are separated by an occluder, the strength of their perceptual grouping behind the occluder depends in part on the possible smoothness of the hidden contour completions (ie, Gestalt ‘good continuation’). We consider if grouping strength also depends on whether the contour completion is convex or concave. We hypothesised that the stronger the grouping between two such regions, the harder it is to resolve their relative stereoscopic depth; and employed accordingly an objective method of relative depth discrimination. The stimulus was in stereo. A horizontal bar in the centre of the image occluded two pairs of planar regions parallel with the image plane. One pair assumed a convex (oval) shape behind the occluder, the other pair a concave (hourglass) shape. The regions in one pair had a slight depth difference. The task was to detect which pair was not coplanar. The convex grouping impeded detection of stereoscopic relative depth (73% vs 86%, F1,10=8.66, p < 0.02). This held even when the convex completion boundaries were less smooth than the concave ones, a result opposite to predictions by Gestalt ‘good continuation’. In a control experiment, the stimulus was viewed with the ‘occluder’ in the background, so grouping was no longer possible. No difference between the two pairs was found. Our results suggest that convexity, known to play a role in figure/ground segmentation, is also significant in perceptual grouping, and can even win out over ‘good continuation’. We also propose an objective method of depth discrimination to study perceptual grouping in general.

Low-light-level three-dimensional video microscope with long working distance objective lenses

1994 ◽  
Vol 52 ◽  
pp. 226-227
Author(s):  
W. Lin ◽  
J. Gregorio ◽  
T.J. Holmes ◽  
D. H. Szarowski ◽  
J.N. Turner
Keyword(s):  
Three Dimensional ◽  
Light Level ◽  
Stereo Pair ◽  
Light Illumination ◽  
Initial Image ◽  
Low Light ◽  
Image Recording ◽  
Depth Discrimination ◽  
Video Microscope ◽  
Working Distance

A low-light level video microscope with long working distance objective lenses has been built as part of our integrated three-dimensional (3-D) light microscopy workstation (Fig. 1). It allows the observation of living specimens under sufficiently low light illumination that no significant photobleaching or alternation of specimen physiology is produced. The improved image quality, depth discrimination and 3-D reconstruction provides a versatile intermediate resolution system that replaces the commonly used dissection microscope for initial image recording and positioning of microelectrodes for neurobiology. A 3-D image is displayed on-line to guide the execution of complex experiments. An image composed of 40 optical sections requires 7 minutes to process and display a stereo pair.The low-light level video microscope utilizes long working distance objective lenses from Mitutoyo (10X, 0.28NA, 37 mm working distance; 20X, 0.42NA, 20 mm working distance; 50X, 0.42NA, 20 mm working distance). They provide enough working distance to allow the placement of microelectrodes in the specimen.

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