3D Watermarking via Normal Vector Perturbation
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Solution Overview
Problem
Current 3D watermarking techniques lack a method to effectively trace and protect 3D modeled objects defined by both a field of points and a field of normal vectors, which are essential for rendering and modeling in CAD systems, as existing methods primarily focus on modifying geometry rather than normal vectors.
Innovation Solution
A method that modifies the field of points while keeping the field of normal vectors unchanged, allowing for the creation of a watermarked 3D modeled object that is difficult to detect visually, by applying perturbations that are statistically less visible and robust against transformations, thereby increasing traceability and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing 3D watermarking techniques modify geometry to embed watermarks, then traceability is improved, but visual detectability increases and rendering quality deteriorates
Solution Approach 1:
The patent extracts the normal vector field from the 3D model and uses it as a separate carrier for watermark embedding. By separating the watermark embedding process from direct geometry modification, the method embeds watermarks in the normal vector space while preserving the original geometry, thus improving traceability without increasing visual detectability or degrading rendering quality
Solution Approach 2:
The patent changes the parameter space for watermark embedding from position coordinates to normal vector directions. By embedding watermarks through subtle modifications to normal vector angles rather than position values, the method achieves reliable traceability while keeping changes imperceptible to visual inspection and maintaining rendering fidelity
2Reliability
If watermark perturbations are made larger to improve detection probability, then traceability is improved, but visual detectability increases
Solution Approach 1:
The patent applies different modification strategies to different components of the 3D model: geometry remains unchanged while normal vectors are subtly adjusted. This local differentiation allows watermark perturbations to be concentrated in the normal vector space where they do not affect visual appearance, enabling high detection probability without increased visual detectability
3Reliability
If geometry is modified to embed watermarks, then traceability is improved, but rendering quality deteriorates
Solution Approach 1:
The patent separates the normal vector field from the geometry and uses this extracted field as the watermark carrier. This separation ensures that watermark embedding occurs in the normal vector space without modifying the geometric positions that define rendering quality, thus maintaining both traceability and rendering fidelity
Solution Approach 2:
The patent changes the embedding parameter from position coordinates to normal vector directions. Since rendering quality is primarily determined by geometric positions and only secondarily by normal vectors, embedding watermarks in normal vector space provides traceability while preserving rendering quality
Data Source
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AI summary
A method is provided for designing a 3D modeled object comprising the steps of providing at least one surface defined by a field of points of the surface and a field of normal vectors normal to the surface; and watermarking the object by modifying the field of points while keeping the field of normal vectors as it is.Such a method provides a technique for tracing a 3D modeled object modeled at least by a field of points of a surface and a field of normal vectors normal to the surface.