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Browse Prior Art Database

Automatic Choice of Color and Opacity for Volume Rendering

IP.com Disclosure Number: IPCOM000107871D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Gresh, DL: AUTHOR

Abstract

Disclosed is a method for automatically choosing colors and opacities for volume rendering. For volumetric data, the opacity and luminosity must both be chosen so that the final picture is bright, but not oversaturated, and so that the entire volume may be seen. The method disclosed here takes into account the thickness of the object, as well as a user-specified attenuation through the volume A and a user-specified total brightness B, to determine appropriate values of opacity and luminosity for volume rendering. The Hue, Saturation, and Value (HSV) color space is used, although the extension to other color spaces is possible. The saturation is set by the user, and the hue is based on the data value, typically blue for minimum data value and red for maximum data value.

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Automatic Choice of Color and Opacity for Volume Rendering

       Disclosed is a method for automatically choosing colors
and opacities for volume rendering.  For volumetric data, the opacity
and luminosity must both be chosen so that the final picture is
bright, but not oversaturated, and so that the entire volume may be
seen.  The method disclosed here takes into account the thickness of
the object, as well as a user-specified attenuation through the
volume A and a user-specified total brightness B, to determine
appropriate values of opacity and luminosity for volume rendering.
The Hue, Saturation, and Value (HSV) color space is used, although
the extension to other color spaces is possible. The saturation is
set by the user, and the hue is based on the data value, typically
blue for minimum data value and red for maximum data value.  The
third parameter in HSV space, "value" or luminosity, and the opacity
D, are determined automatically based on the size of the object, such
that the total integrated intensity when viewing the object along its
longest axis (thickness T) is equal to B.

      Looking at the object, the brightness B registered is given by

                            (Image Omitted)

where z is the direction into the screen, and znear and zfar are the
near and far edges of the object along the viewing direction.  L is
the luminosity (color) of the points along the viewing direction, and
D is the opacity.  Choosing the...