Intuitive Boundary Patch Shape Control via Tangent Magnitude
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Solution Overview
Problem
Existing CAD systems face challenges in constructing boundary patches that meet boundary constraints while maintaining a fair shape, especially for n-sided regions, as standard operators are not applicable and internal smoothness is difficult to ensure, leading to limited control over the patch's interior shape.
Innovation Solution
A computer-implemented method that generates a surface based on boundary edges, modifies tangent magnitudes along these edges, and uses a modified spherical coordinate system to adjust the surface shape, allowing for intuitive modification of boundary patches by varying tangent magnitudes and scale factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a trimmed NURBS surface is used to represent an n-sided patch, then the patch can be constructed to meet boundary constraints, but the interior shape control is limited and the patch is locked by boundary constraints
Solution Approach 1:
The invention segments the control of the n-sided patch by separating boundary constraint satisfaction from interior shape control. It divides the patch into regions influenced by different control mechanisms, allowing independent adjustment of boundary adherence and interior geometry through the use of control points and tension parameters that affect specific regions without fully constraining the entire patch.
Solution Approach 2:
The invention introduces dynamic control mechanisms that allow the patch shape to be adjusted in real-time. By implementing tension control and iterative relaxation algorithms, the system enables users to dynamically modify interior shape parameters while maintaining boundary constraints, transforming a static locked surface into a dynamically adjustable geometric form.
2Ease of operation
If additional interior constraints such as interior curves and points are inserted to control patch shape, then some tension control is achieved, but artifacts are introduced and patch quality suffers
Solution Approach 1:
The invention applies local quality control by allowing different regions of the patch to have different levels of constraint and control. Instead of uniformly applying tension control across the entire patch, the system enables localized adjustment of interior shape parameters in specific regions, maintaining high patch quality while achieving the desired tension control effects where needed.
Solution Approach 2:
The invention changes the control parameters from fixed interior constraints to adjustable tension parameters. By using relaxation algorithms and iterative optimization, the system modifies geometric parameters dynamically to achieve smooth tension control without introducing artifacts, maintaining mathematical continuity and surface quality throughout the patch.
3Manufacturing precision
If standard surface operators (loft, sweep, fillet) are used, then well-defined rectangular domain surfaces are created, but they are not applicable to n-sided regions with arbitrary boundaries
Solution Approach 1:
The invention creates a universal patch construction method that can handle both rectangular and arbitrary n-sided regions. By implementing a generalized boundary patch algorithm that works with any closed boundary curve configuration, the system provides a multi-functional solution that replaces the need for separate operators for different polygon types, maintaining mathematical precision across all geometric configurations.
Data Source
AI summary
A method and system for computer aided design (CAD) is disclosed for intuitive shape control of boundary patch. A boundary patch is also known as n-sided patch which is defined by a number of input curves/edges. Continuity constraints (G0, G1 and G2) can be specified individually for the input curves. Boundary patch is primarily used to cover a relatively flat area where other modeling operators such as loft, sweep or fillet cannot apply due to irregular shape of the area. The present invention provides a technique to directly manipulate boundary tangent magnitude of a patch and allows the user to deform the patch shape in a very intuitive way. Thus, the present invention is especially useful for industrial design applications.