Chromatic Shadows for Improved Perception

Veronika Šoltészová, Daniel Patel, Ivan Viola

INPROCEEDINGS, Proc. Non-photorealistic Animation and Rendering (NPAR 2011), 2011

• www

Abstract

Soft shadows are effective depth and shape cues. However, traditional shadowing algorithms decrease the luminance in shadow areas. The features in shadow become dark and thus shadowing causes information hiding. For this reason, in shadowed areas, medical illustrators decrease the luminance less and compensate the lower luminance range by adding color, i.e., by introducing a chromatic component. This paper presents a novel technique which enables an interactive setup of an illustrative shadow representation for preventing overdarkening of important structures. We introduce a scalar attribute for every voxel denoted as shadowiness and propose a shadow transfer function that maps the shadowiness to a color and a blend factor. Typically, the blend factor increases linearly with the shadowiness. We then let the original object color blend with the shadow color according to the blend factor. We suggest a specific shadow transfer function, designed together with a medical illustrator which shifts the shadow color towards blue. This shadow transfer function is quantitatively evaluated with respect to relative depth and surface perception.

Published

Proc. Non-photorealistic Animation and Rendering (NPAR 2011)

• Pages: 105–115
• Location: Vancouver, Canada
• Project: IllustraSound, MedViz, Illustrative Visualization
• URL: http://dx.doi.org/10.1145/2024676.2024694

Media

BibTeX

@inproceedings{solteszova11chromatic,
 title =  {Chromatic Shadows for Improved Perception},
 author = {Veronika \v{S}olt{\'e}szov{\'a} and Daniel Patel and Ivan Viola},
 booktitle = {Proc. Non-photorealistic Animation and Rendering (NPAR 2011)},
 year =  {2011},
 pages =  {105--115},
 abstract = {Soft shadows are effective depth and shape cues. However, 
traditional shadowing algorithms decrease the luminance in shadow
areas. The features in shadow become dark and thus shadowing causes
information hiding. For this reason, in shadowed areas, medical 
illustrators decrease the luminance less and compensate the lower 
luminance range by adding color, i.e., by introducing a chromatic 
component. This paper presents a novel technique which enables an 
interactive setup of an illustrative shadow representation for 
preventing overdarkening of important structures. We introduce a 
scalar attribute for every voxel denoted as shadowiness and propose 
a shadow transfer function that maps the shadowiness to a color and 
a blend factor. Typically, the blend factor increases linearly with 
the shadowiness. We then let the original object color blend with 
the shadow color according to the blend factor. We suggest a 
specific shadow transfer function, designed together with a medical 
illustrator which shifts the shadow color towards blue. This shadow 
transfer function is quantitatively evaluated with respect to 
relative depth and surface perception.},
 location = {Vancouver, Canada},
 url = {http://dx.doi.org/10.1145/2024676.2024694},

}