Light fields and shape from shading

Van Doorn, A.J.; Koenderink, J.J.; Wagemans, J.

doi:doi:10.1167/11.3.21

Light fields and shape from shading

Title

Light fields and shape from shading

Author

Van Doorn, A.J.
Koenderink, J.J.
Wagemans, J.

Faculty

Industrial Design Engineering

Department

Industrial Design

Date

2011-03-29

Abstract

From a theoretical point of view, the use of the shading cue involves estimates of the light field and thus observers need to judge the light field and the shape simultaneously. The conventional stimulus in perceptual experiments, a circular disk filled with a monotonic gradient on a uniform surround, represents a local shading or tonal gradient. In typical scenes, such gradients vary smoothly from point to point over large areas, whereas light fields are globally defined and tend to be invariant over large parts of the scene. Hence, it is hardly surprising that multi-local shape estimates tend to synchronize although previous reports of such synchronies involved uniform, homogeneous light fields. Here, we consider more complicated and more realistic light fields. We present extensive, highly structured, quantitative observations using novel paradigms. Human observers are able to deal with some structured light fields but totally fail in others, even though these may be formally similar (like radial and circular fields). Observers respond very differently in some cases where the light fields differ only by sign, like converging and diverging fields. These results can be qualitatively understood on the basis of a few simple assumptions, mainly global top-down template matching of peripheral local data.

Subject

light fields
illuminance flow
shape from shading
perceptual ambiguity
switching
synchronization
template matching

To reference this document use:

http://resolver.tudelft.nl/uuid:372cd97c-a424-491b-b8c7-bfa01c7488c4

DOI

https://doi.org/10.1167/11.3.21

Publisher

ARVO

ISSN

1534-7362

Source

Journal of Vision, 11 (3), 2011