Photometric Tangent Map Creation with Low-Frequency Normal Correction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional 3D scanning techniques using photogrammetry suffer from low-frequency inconsistencies in photometric surface normals, leading to inaccurate 3D model representations and undesirable low-frequency variations in tangent maps, which affect the consistency and quality of the rendered 3D models.

Innovation Solution

A system and method that corrects photometric surface normals using a base 3D mesh and mesh density maps to generate a tangent map free from low-frequency variations, by applying a correction based on a base normal map and mesh density map to convert the photometric surface normal from world-space to tangent-space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If photogrammetry is used to capture 3D object surfaces, then micro-geometry level surface description is achieved, but low-frequency inconsistencies in photometric surface normals occur

Engineering Contradiction:

Improvesurface normal accuracyVSAvoidlow-frequency consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments the surface normal information into two distinct components: high-frequency photometric surface normals (capturing micro-geometry details) and low-frequency geometric surface normals (capturing overall shape). This segmentation allows each component to be processed and corrected independently, resolving the contradiction by preserving the detailed surface information while eliminating low-frequency inconsistencies through the geometric model.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a geometric surface normal map as an intermediary between the photometric surface normals and the final tangent map. This intermediary provides a consistent low-frequency reference that mediates the inconsistencies in the photometric data, allowing the high-frequency details to be preserved while the low-frequency errors are corrected through the geometric model.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If photometric surface normal is used for tangent map creation, then micro-geometry details are captured, but low-frequency variations and artifacts are introduced

Engineering Contradiction:

Improvetangent map accuracyVSAvoidlow-frequency artifacts

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the low-frequency geometric information from the photometric surface normals by comparing them with the geometric surface normals derived from the 3D mesh. This extraction process separates the harmful low-frequency variations from the useful high-frequency details, allowing the artifacts to be removed while preserving the micro-geometry information in the corrected tangent map.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the low-frequency inconsistencies, which are normally harmful artifacts, into a useful correction signal. By computing the difference between photometric and geometric surface normals, the low-frequency errors are transformed into a correction map that can be applied to improve the overall tangent map quality, turning the harmful artifacts into a benefit for achieving photorealistic reconstruction.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If conventional photogrammetry processing is used, then 3D model generation is achieved, but consistency and quality of rendered models are reduced

Engineering Contradiction:

Improve3D model generation speedVSAvoidrendered model consistency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent performs preliminary correction of the photometric surface normals by computing the difference with geometric surface normals before generating the tangent map. This preliminary action eliminates low-frequency inconsistencies early in the processing pipeline, ensuring that the subsequent 3D model generation and rendering operations work with consistent data, thereby maintaining both productivity and reliability.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250232531A1Normal and mesh detail separation for photometric tangent map creation

Publication Date: 2025.07.17 SONY GROUP CORP

AI summary

A system and method for normal and mesh detail separation for photometric tangent map creation is provided. The system acquires a base three-dimensional (3D) mesh of an object and a photometric surface normal corresponding to the object. The system computes a mesh density map based on the base 3D mesh and a base normal map based on vertex normal information included in the base 3D mesh. The system determines a correction on the photometric surface normal based on the base normal map and the mesh density map. The system generates a corrected photometric surface normal based on an application of the correction.