Virtual Environment Illumination Estimation Using Shadow Maps

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Solution Overview

Problem

Current methods for simulating global illumination in virtual environments are either memory-intensive and computationally costly or provide coarse results, failing to achieve high-quality, rapid estimation and realistic display of light diffusion and reflection.

Innovation Solution

A method that uses shadow maps to store distance information from light sources to virtual environment points, allowing for efficient estimation of light quantities by grouping points and reducing the need for costly visibility calculations, and employing grouping techniques to accelerate calculations while preserving lighting quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If radiosity methods are used to simulate global illumination, then the quality of illumination estimation is improved, but the memory requirements and calculation power increase significantly

Engineering Contradiction:
Improveillumination estimation qualityVSAvoidcalculation power
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The virtual environment is decomposed into discrete patches, and the illumination calculation is segmented by separating direct and indirect lighting components. This allows selective processing of different spatial regions and lighting contributions, reducing overall computational burden while maintaining quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A pre-computed depth buffer is generated before the main illumination calculation. This preliminary structure enables efficient occlusion testing during indirect lighting computation, avoiding redundant visibility calculations and reducing calculation power requirements.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If radiosity methods are used to simulate global illumination, then the quality of illumination estimation is improved, but the memory requirements increase significantly

Engineering Contradiction:
Improveillumination estimation qualityVSAvoidmemory requirements
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The method extracts only the essential geometric information (depth buffer) needed for occlusion testing, rather than storing complete scene geometry or radiosity matrices. This selective extraction significantly reduces memory requirements while preserving illumination quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of storing and processing complete scene geometry multiple times, the method uses a single depth buffer copy that suffices for all occlusion tests. This eliminates redundant geometric data storage and reduces memory consumption.

Inventive Principle:
Principle #26Copying

3Measurement precision

If ray tracing methods are used to follow light paths, then the realism of light diffusion is improved, but the calculation power required increases

Engineering Contradiction:
Improvelight diffusion realismVSAvoidcalculation power
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The method substitutes complex ray tracing mechanics with a simplified radiosity approach enhanced by depth buffer occlusion tests. This replacement maintains light diffusion realism through indirect lighting calculations while dramatically reducing calculation power requirements by avoiding exhaustive ray tracing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If screen space approximations are used, then the calculation speed is improved, but the quality of illumination result deteriorates

Engineering Contradiction:
Improvecalculation speedVSAvoidillumination result quality
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The depth buffer serves as an intermediary structure that bridges screen-space efficiency and quality. It enables accurate occlusion determination in screen space without requiring full 3D geometry processing, thus maintaining calculation speed while improving illumination quality over pure screen-space methods.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2437219B1Method for estimating the quantity of light received at a point of a virtual environment
Publication Date: 2015.08.12 THOMSON LICENSING SA
  • EP2437219B1 patent drawingFigure 1A~1B
  • EP2437219B1 patent drawingFigure 2
  • EP2437219B1 patent drawingFigure 3

AI summary

The invention relates to a method for estimation of the quantity of light received at a point P (43) of a virtual environment (1) that comprises several first points lit by a light source (10), said first points forming a plurality of groups each comprising at least one first point. In order to improve the display while minimising the required calculation time, the method comprises steps for: - estimating, for each group, the quantity of incident light received, - estimating a surface comprising the point P (43) grouping at least some of the points of the virtual environment visible from a viewpoint (40), - estimating at least a first group (321, 351) of said plurality of groups contributing to the lighting of said point P (43) by reflection of the incident light received from said light source (10) according to at least one item of occlusion information associated with said surface, - estimating the quantity of light received by said point P (43) from the quantity of incident light received by said at least one first group (321, 351) according to the at least one item of reflectance information associated with said at least one first group.