Subdivision Surface Engraving via Mesh-to-NURBS Conversion
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Solution Overview
Problem
Existing CAD systems lack the capability for local changes on surfaces with arbitrary topology, limiting the design flexibility of 3D modeled objects.
Innovation Solution
A computer-implemented method that allows designing a 3D modeled object by defining a base mesh associated with a subdivision surface and a mesh-to-NURBS-surface conversion algorithm, enabling local modifications through a deformation map based on a 2D image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If subdivision surface technology is used to achieve arbitrary topology, then topology flexibility is improved, but local modification capability deteriorates
Solution Approach 1:
The patent segments the subdivision surface into multiple NURBS surface patches, each capable of independent local modification. The base mesh is divided into regions that can be selectively converted to NURBS surfaces, allowing localized editing without affecting the entire surface. This segmentation enables users to modify specific areas while preserving the overall arbitrary topology of the subdivision surface.
Solution Approach 2:
The patent applies local quality by enabling NURBS surface conversion only in specific regions of the base mesh where local modification is needed. Different regions of the surface can have different properties - some areas as subdivision surfaces for topology flexibility, others as NURBS surfaces for local editability. This allows the surface to have different functional qualities in different locations.
2Ease of operation
If NURBS technology is used to achieve local modification capability, then local editing is improved, but topology flexibility deteriorates
Solution Approach 1:
The patent merges NURBS surface technology with subdivision surface technology in a hybrid approach. NURBS surface patches are integrated into the subdivision surface framework, allowing the system to combine the local modification capability of NURBS with the topology flexibility of subdivision surfaces. The converted patches maintain continuity with the surrounding subdivision surface geometry.
3Ease of operation
If the base mesh is converted to NURBS surface, then local modification capability is improved, but the influence scope worsens
Solution Approach 1:
The patent segments the base mesh into multiple NURBS surface patches rather than converting the entire mesh. Each patch is a localized region that can be independently modified. This segmentation restricts the influence scope of modifications to only the specific patch being edited, preventing changes from propagating across the entire surface.
Solution Approach 2:
The patent applies local quality by giving different regions different properties - converted NURBS patches in areas requiring local modification, and original subdivision surface geometry in areas where global topology flexibility is needed. This ensures that modifications are localized and do not unnecessarily affect other parts of the surface.
Data Source
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AI summary
It is the method comprising the steps of defining (S10), by a user, a base mesh (B0) associated to a subdivision surface and to a corresponding predetermined mesh-to-NURBS-surface conversion algorithm (PCCM(·)), the subdivision surface representing the 3D modeled object; defining (S20), by the user, a 2D image and a location for engraving the 2D image on the subdivision surface; and determining (S30) a NURBS surface (S1) that corresponds to applying (S36) a deformation map (i,j ↦ Δ(i,j)) on the result (S0 = PCCM(B0)) of performing (S34) the mesh-to-NURBS-surface conversion algorithm to the base mesh, the deformation map including displacement vectors provided for positions of the result of performing (S34) the mesh-to-NURBS-surface conversion algorithm to the base mesh, the positions corresponding to the location for engraving the 2D image, the displacement vectors being computed (S32) based on corresponding pixel values of the 2D image. Such a method improves the design of a 3D modeled object.