Invalidity dossier
US 6211883
Patch-flatness test unit for high order rational surface patch rendering systems
Current assignee: Avago Technologies International Sales Pte Ltd
Added 9/23/2026, 12:26:28 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6,211,883 B1
Title: Patch-flatness test unit for high order rational surface patch rendering systems
Patent number: US 6,211,883 B1
Application number: US08/921,918
Inventor: Vineet Goel
Original assignee: LSI Logic Corp
Current assignee listed: Avago Technologies International Sales Pte Ltd
Prior art date: 1997-04-08
Filing date: 1997-08-27
Publication (grant) date: 2001-04-03
Legal status as listed: Expired – Lifetime (anticipated expiration 2017-04-08)
Purpose and plain-language scope (from the supplied text):
The patent relates to converting object representations into images for graphical display, specifically rendering a surface represented by a set of Bezier patches. A rational Bezier patch is described as a generalization of a Bezier patch having a fourth equation, with surface points given by (X/W, Y/W, Z/W). Rendering is performed by subdividing a patch until subpatches are flat enough to approximate with a quadrilateral.
The disclosed patch-flatness test unit determines patch flatness from a set of control points, using eight stages: (1) receive and store control points; (2) determine control point coordinate differences from pairs of control points; (3) determine absolute values of those differences; (4) determine multiplicand pairs; (5) multiply multiplicand pairs to determine products; (6) determine control point deviations and deviation tolerances; (7) determine a deviation flag indicating whether deviations are less than tolerances; and (8) determine edge straightness and patch flatness flags.
According to the excerpt, edges and internal curves of a subpatch are determined to be straight if intermediate control points of a curve lie within a tolerance range of a straight line between the curve's endpoints, with the tolerance range chosen relative to pixel resolution so flatness is found when curvature cannot be perceived relative to a flat surface.
What the excerpt does not establish: It does not provide the full claims, complete figures, the full description, or any prosecution history. It does not establish validity, enforceability, or the accuracy of listed assignees or legal status, and it does not show prior art beyond the identified prior art date.
Generated 10/1/2026, 9:53:37 PM
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Assignment history
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Prior art
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Obviousness
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Derivative works
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