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Shape perception from shading under ...

Liu, Baoxia.

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Shape perception from shading under natural lighting conditions.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Shape perception from shading under natural lighting conditions./
Author:	Liu, Baoxia.
Description:	103 p.
Notes:	Adviser: James T. Todd.
Contained By:	Dissertation Abstracts International63-07B.
Subject:	Psychology, Cognitive. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3059289
ISBN:	0493748318

Shape perception from shading under natural lighting conditions.
Liu, Baoxia.

Shape perception from shading under natural lighting conditions. - 103 p.

Adviser: James T. Todd.

Thesis (Ph.D.)--The Ohio State University, 2002.

The present research was designed to investigate the effects of the three components (i.e. cast shadows, indirect illuminations and specular highlights) on the shape perception and also the process of resolving the ambiguity in shaded images.

ISBN: 0493748318Subjects--Topical Terms:

1017810
Psychology, Cognitive.

Shape perception from shading under natural lighting conditions.
LDR:03119nam 2200325 a 45 001 936764
005 20110510
008 110510s2002 eng d
020 $a 0493748318
035 $a (UnM)AAI3059289
035 $a AAI3059289
040 $a UnM $c UnM
100 1 $a Liu, Baoxia. $3 1260597
245 1 0 $a Shape perception from shading under natural lighting conditions.
300 $a 103 p.
500 $a Adviser: James T. Todd.
500 $a Source: Dissertation Abstracts International, Volume: 63-07, Section: B, page: 3490.
502 $a Thesis (Ph.D.)--The Ohio State University, 2002.
520 $a The present research was designed to investigate the effects of the three components (i.e. cast shadows, indirect illuminations and specular highlights) on the shape perception and also the process of resolving the ambiguity in shaded images.
520 $a Much of the recent research on the visual perception of shape from shading has employed computer generated images, which often do not include several basic components of shading that are common in natural scenes, such as cast shadows, indirect illuminations and specular highlights. In addition, the ambiguity in shaded images has been a puzzle for the studies on “shape perception from shading” since the 18th century.
520 $a In the first three experiments, convex and concave half spheroids were used as stimuli. The presence of each of the three components could be turned on or off independently, the illumination direction could be from top or bottom, and the images were presented to observers in all possible combinations. Both the perception of the sign of curvature and the depth magnitude were tested. The results revealed clear biases in observers' judgments of the sign of curvature (i.e. convexity bias and overhead illumination bias). Different observers had different biases. Observers' estimations of depth magnitude were affected by the sign of curvature, the presence or absence of cast shadows and the shininess of surfaces.
520 $a The fourth and fifth experiments used images of randomly shaped objects as stimuli. Shape perception was very accurate comparing to the real shapes and it was also reliable across subjects and different illumination directions. The perception of complex shapes seemed to be more stable than convex and concave bumps. Even when the occluding contour of the complex shapes was masked off, shape perception was still very accurate and reliable across observers and illumination directions.
520 $a The estimations of illumination directions were also tested. The results showed close relationship between the estimated illumination direction and the judgment of the sign of curvature for convex and concave bumps. However, the illumination information may not be necessary for the perception of complex shapes.
590 $a School code: 0168.
650 4 $a Psychology, Cognitive. $3 1017810
650 4 $a Psychology, Experimental. $3 517106
690 $a 0623
690 $a 0633
710 2 0 $a The Ohio State University. $3 718944
773 0 $t Dissertation Abstracts International $g 63-07B.
790 $a 0168
790 1 0 $a Todd, James T., $e advisor
791 $a Ph.D.
792 $a 2002
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3059289