Ray Tracing Noise Reduction via Light Path Grouping

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Solution Overview

Problem

Current ray tracing techniques are prone to noise due to under sampling of illumination and materials, leading to suboptimal image quality.

Innovation Solution

A method for determining the quantity of light received by an element in a scene by identifying associated light paths, selecting similar paths using heuristic criteria, and averaging light quantities to reduce noise through path space filtering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional ray tracing is used to render images, then the rendering process is relatively simple and fast, but the image quality is poor due to noise from under sampling

Engineering Contradiction:
Improveimage qualityVSAvoidrendering complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple similar light paths together to form groups, where paths with similar properties (geometry, materials, illumination) are combined. This merging allows statistical information to be shared across grouped paths, reducing noise in the final image while maintaining manageable rendering complexity through organized path grouping.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent creates copies of statistical information from previously rendered light paths and reuses them for similar paths. By identifying paths with similar characteristics and copying their statistical data, the system reduces redundant computation and improves image quality without proportionally increasing rendering complexity.

Inventive Principle:
Principle #26Copying

2Measurement precision

If more light paths are sampled to reduce noise, then image quality improves, but the rendering time and computational cost increase

Engineering Contradiction:
Improvenoise reductionVSAvoidrendering time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary grouping and statistical analysis of light paths during the rendering process. By organizing paths into groups based on similarity criteria beforehand and pre-computing statistical information for each group, the system reduces the computational burden for individual path evaluation, thereby reducing noise without proportionally increasing total rendering time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter of path evaluation from individual path analysis to grouped path analysis. By transforming the rendering approach to work with groups of similar paths rather than individual paths, the system achieves better noise reduction efficiency, as statistical information can be shared and averaged across multiple paths within each group.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If under sampling is used to speed up rendering, then rendering speed increases, but noise in the image increases

Engineering Contradiction:
Improverendering speedVSAvoidillumination sampling accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent combines multiple under-sampled light paths into groups based on similarity in geometry, materials, and illumination characteristics. By merging these paths and sharing statistical information within groups, the system recovers illumination sampling accuracy that would otherwise be lost due to under sampling, while maintaining the faster rendering speed enabled by processing groups rather than individual paths.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements feedback mechanisms where statistical information from rendered paths is used to guide the selection and grouping of subsequent paths. This feedback allows the system to efficiently allocate sampling resources to areas needing more precision while maintaining overall rendering speed, as the system learns from previous path evaluations to optimize future sampling decisions.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS9501865B2System, method, and computer program product for determining a quantity of light received by an element of a scene
Publication Date: 2016.11.22 NVIDIA CORP
  • US9501865B2 patent drawing
  • US9501865B2 patent drawing
  • US9501865B2 patent drawing

AI summary

A system, method, and computer program product are provided for determining a quantity of light received by an element of a scene. In use, a quantity of light received by a first element of the scene is determined by averaging a quantity of light received by elements of the scene that are associated with a selected set of light paths.