Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Patent
1997-02-28
1999-01-26
Nguyen, Phu K.
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
G06F 1500
Patent
active
058643443
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
1. Field of the Invention
The described invention provides a computer graphics circuit to render gaseous image such as cloud, fog and steam. The circuit is comprised with gaussian random number generator, parametric free curve generator, filter and synthesizer of gaseous object and surface-defined object. This invention provides a real-time rendering of gaseous image in computer graphics and is applied to a graphics processor which is used for a visualization of virtual reality system.
2. Background Art
In a computer graphics, 3-dimensional object is often defined with surface or solid model and a realistic image is obtained by applying light-reflection to these defined objects. There are two schemes in rendering, polygon rendering and raytracing or radiosity. An image of natural phenomena such as fog and cloud which has a characteristics of complexity and dynamic change of shape is often rendered with raytracing algorithm. In the gaseous object, random light-reflection is also applied. Beside, it needs a synthesis with surface-defined object. Due to these large computation cost, there is no hardware circuit which is commercially available now for rendering the gaseous object as a volumed image but it has been rendered by software scheme. As the result, to display gaseous object with animation corresponding with a walk-through in virtual reality system has not yet realized up to now. A composition of 2-dimensional camera image or texture mapping technology has been used for it. This 2-dimensional approach limits the expressive power of 3-D scenes where viewer's eyes move into the gaseous object. Thus, to create the scene where the gaseous object dynamically flows before eyes needs the volume-rendering and the synthesis of gaseous object with surface-defined objects. A hardware implementation for these functions may be only way to realize a real-time rendering to cope with large computation cost. The implementation of real-time renderer for gaseous object in hardware has following processing: (1) definition of amorphous structured images with turbulent models; (2) shading with reflection; (3) transparency and filtering; (4) synthesis of gaseous and surface-defined objects. All of these processing have been considered to do only by software. This invention provides the hardware circuit for gaseous object rendering to get a realistic images in real time in virtual reality system.
SUMMARY OF THE INVENTION
This invention is specified a gaseous object rendering circuit comprising: (1) Gaussian random number generator to output quasi-random coordinates for positioning primitives of gaseous object. The gaseous objects are organized with hierarchical structures consisting of primitive, segment and object in this system. The segment consists of a mass of primitives (minimum particles) while the object is composed by combining multiple segments together; (2) interpolation circuit used to compute parametric free curve which defines a origin of segment (relative origin of primitives); (3) RAM(Random Access Memory) to store a predefined pattern which is mapped to each primitive to give a certain shape; (4) shading circuit to calculate a diffused reflection with normal vector of primitive and light-source. The normal vector is defined to have a opposite direction along to the straight line connected with the normal reference point and primitive point. The reference point is given arbitrary in 3-dimensional space for each segment; (5) means for defining overlapped number of primitive for getting a transparency in synthesis of gaseous and surface-defined object which are rendered independently. The overlapped number can be calculated when a destination primitive is already stored into frame buffer and executed a hidden primitive removal(using z-buffer). (6) means for reading intensity(intensity and overlapped number for gaseous object) and z value of both primitives from frame buffer synchronizing with a raster scanning and applying intensity and overlapped number of gaseous object to filters, and (7
REFERENCES:
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patent: 5745125 (1998-04-01), Deering et al.
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