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Method to Generate the Shadow of Arbitrary-Shaped Three-Dimensional Objects

IP.com Disclosure Number: IPCOM000101192D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 93K

Publishing Venue

IBM

Related People

Lien, L: AUTHOR [+3]

Abstract

Disclosed is a system for generating the shadows of three-dimensional objects. The basic idea of the method is to reduce the number of dimensions of the objects to be processed. It is accomplished by dividing the three-dimensional objects into two-dimensional profiles, or slices, by transforming them, and by bitwise ORing (summing) them.

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Method to Generate the Shadow of Arbitrary-Shaped Three-Dimensional Objects

       Disclosed is a system for generating the shadows of
three-dimensional objects.  The basic idea of the method is to reduce
the number of dimensions of the objects to be processed.  It is
accomplished by dividing the three-dimensional objects into
two-dimensional profiles, or slices, by transforming them, and by
bitwise ORing (summing) them.

      In the following description, a three-dimensional character
pattern is used as an example (Fig. 1).  The module structure of the
system is shown in Fig. 2. It is composed of four modules:  a
clipper, a calculator, an bitmap editor, and a controller of other
modules.  The controller executes the program whose rough control
structure is shown in Fig. 3. The program repeats the clippings and
the two-dimensional perspective transformations in its main loop.  As
the first step of the main loop, the clipper divides the given
three-dimensional object into a set of two-dimensional bitmap
profiles by the method of three-dimensional clipping, as shown in
Fig. 4, and passes the bitmap profiles to the bitmap editor.  By this
division, the operations applied to the unit of objects become
simpler.  This module can be implemented as a software module, or as
a graphics hardware to speed up the processing.  When the object
originates from a two-dimensional bitmap, as in Fig.  4, this
clipping takes little time.  Next, the calculator gets the locations
of the light, the shadow plane, and the profile, and computes the
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