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Browse Prior Art Database

Fast Drawing of Image Color Contours

IP.com Disclosure Number: IPCOM000105076D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Chapman, S: AUTHOR

Abstract

Described is a fast method of producing color contour lines on computer generated three dimensional graphics images with the minimum of computing. Avoided is the necessity to compute the positions fo the pixels to be colored along the contour line level.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 96% of the total text.

Fast Drawing of Image Color Contours

      Described is a fast method of producing color contour lines on
computer generated three dimensional graphics images with the minimum
of computing.  Avoided is the necessity to compute the positions fo
the pixels to be colored along the contour line level.

      In many computer graphics applications of 3-dimensional
modelling.  a terrain map will be produced showing the heights of
mountains, etc.  These are usually color coded by height.  Many times
it is necessary to draw in contour lines at specified intervals.  The
usual technique is to compute which pixedls in the image correspond
to each height and then reqrite those pixels in the contour color.

      Disclosed is a scheme that provides a simple and rapid method
for generating contours by writing directly into the hardware palette
at the required intervals.  In this way, the contours will appear in
the image without any image manipulation.  Fig. 1 shows a simple
image with height mapped to color using the palette shown.  This
palette has no contour lines imbedded and thus the image has no
contour lines.  Writing white lines (or indeed lines of any
appropriate color) appearing in the palette at the location shown
(Fig. 2) results in the contour lines appearing in the image.  This
technique has been applied to a pseudo-3d viewer within the IBM UK
Science Center.  This method is very much faster than computing a new
image, and the contour lines may be eas...