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Is the perception of 3D shape from shading based on assumed reflectance and illumination?

Todd JT, Egan EJ, Phillips F - Iperception (2014)

Bottom Line: A gauge figure adjustment task was used to measure observers' perceptions of local surface orientation on the depicted surfaces, and the probe points included 60 pairs of regions that both had the same orientation.The results show clearly that observers' perceptions of these three types of stimuli were remarkably similar, and that probe regions with similar apparent orientations could have large differences in image intensity.This latter finding is incompatible with any process for computing shape from shading that assumes any plausible reflectance function combined with any possible homogeneous illumination.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, The Ohio State University, Columbus, OH; e-mail: todd.44@osu.edu.

ABSTRACT
The research described in the present article was designed to compare three types of image shading: one generated with a Lambertian BRDF and homogeneous illumination such that image intensity was determined entirely by local surface orientation irrespective of position; one that was textured with a linear intensity gradient, such that image intensity was determined entirely by local surface position irrespective of orientation; and another that was generated with a Lambertian BRDF and inhomogeneous illumination such that image intensity was influenced by both position and orientation. A gauge figure adjustment task was used to measure observers' perceptions of local surface orientation on the depicted surfaces, and the probe points included 60 pairs of regions that both had the same orientation. The results show clearly that observers' perceptions of these three types of stimuli were remarkably similar, and that probe regions with similar apparent orientations could have large differences in image intensity. This latter finding is incompatible with any process for computing shape from shading that assumes any plausible reflectance function combined with any possible homogeneous illumination.

No MeSH data available.


Related in: MedlinePlus

A toon-rendered image that depicts the occlusion contours from the stimuli in Experiment 1. This image has been cropped relative to the one that was used in the Experiment.
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Figure 6: A toon-rendered image that depicts the occlusion contours from the stimuli in Experiment 1. This image has been cropped relative to the one that was used in the Experiment.

Mentions: There were only two possible stimuli in this experiment: the Lambertian surface with homogeneous illumination used in Experiment 1 (see Figure 2A), and a toon-rendered version of the same surface that only depicted the occlusion boundaries (see Figure 6). These displays were judged by two of the naïve observers who participated in Experiment 1. In all other respects, the methods were identical to those reported for the previous study.


Is the perception of 3D shape from shading based on assumed reflectance and illumination?

Todd JT, Egan EJ, Phillips F - Iperception (2014)

A toon-rendered image that depicts the occlusion contours from the stimuli in Experiment 1. This image has been cropped relative to the one that was used in the Experiment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4441026&req=5

Figure 6: A toon-rendered image that depicts the occlusion contours from the stimuli in Experiment 1. This image has been cropped relative to the one that was used in the Experiment.
Mentions: There were only two possible stimuli in this experiment: the Lambertian surface with homogeneous illumination used in Experiment 1 (see Figure 2A), and a toon-rendered version of the same surface that only depicted the occlusion boundaries (see Figure 6). These displays were judged by two of the naïve observers who participated in Experiment 1. In all other respects, the methods were identical to those reported for the previous study.

Bottom Line: A gauge figure adjustment task was used to measure observers' perceptions of local surface orientation on the depicted surfaces, and the probe points included 60 pairs of regions that both had the same orientation.The results show clearly that observers' perceptions of these three types of stimuli were remarkably similar, and that probe regions with similar apparent orientations could have large differences in image intensity.This latter finding is incompatible with any process for computing shape from shading that assumes any plausible reflectance function combined with any possible homogeneous illumination.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, The Ohio State University, Columbus, OH; e-mail: todd.44@osu.edu.

ABSTRACT
The research described in the present article was designed to compare three types of image shading: one generated with a Lambertian BRDF and homogeneous illumination such that image intensity was determined entirely by local surface orientation irrespective of position; one that was textured with a linear intensity gradient, such that image intensity was determined entirely by local surface position irrespective of orientation; and another that was generated with a Lambertian BRDF and inhomogeneous illumination such that image intensity was influenced by both position and orientation. A gauge figure adjustment task was used to measure observers' perceptions of local surface orientation on the depicted surfaces, and the probe points included 60 pairs of regions that both had the same orientation. The results show clearly that observers' perceptions of these three types of stimuli were remarkably similar, and that probe regions with similar apparent orientations could have large differences in image intensity. This latter finding is incompatible with any process for computing shape from shading that assumes any plausible reflectance function combined with any possible homogeneous illumination.

No MeSH data available.


Related in: MedlinePlus