Browse Prior Art Database

Smoothing ISO-Surfaces Composed of Polygons

IP.com Disclosure Number: IPCOM000121787D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 51K

Publishing Venue

IBM

Related People

Watson, D: AUTHOR

Abstract

A method is disclosed whereby faceted iso-surfaces in a graphics processor can be smoothed after creation.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 59% of the total text.

Smoothing ISO-Surfaces Composed of Polygons

      A method is disclosed whereby faceted iso-surfaces in a
graphics processor can be smoothed after creation.

      When creating an iso-surface within a three-dimensional scalar
field using polygons, the resulting boundary surface may appear
faceted.  The degree of faceting depends upon the algorithm used to
create the polygons on the surface within a single grid cube and is
greatest when a geometric normal has been calculated for each polygon
rather than a unique vertex normal.

      A solution to the problem of faceting by a smoothing method is
here described.  Each polygon remains in storage after it has been
generated.  When all polygons have been generated for the iso-surface
the resultant mesh is processed.  For each vertex of a polygon the
mesh is scanned to find all other polygons which share the vertex.
When all polygons which share this vertex have been identified the
vertex normal is calculated by averaging the geometric normals of
each of the contributing polygons.  This method has been implemented
in code known as WINVIS90 and gives a significant visual improvement
over the faceted boundary. The method is applicable in situations
where no sharp discontinuities exist in the boundary of an
iso-surface.  If each vertex was marked as being on a discontinuity
(or not), then the method could be used in any polygonal graphics
application.  The approach is then universally applicable.

      An al...