Integration Cone Tracing for Global Illumination

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Solution Overview

Problem

Conventional Monte Carlo based ray tracing is inefficient for complex scenes due to high processing overhead and random data access requirements, leading to significant noise in rendered images, especially at high resolutions, making it impractical for feature film rendering.

Innovation Solution

Integration cone tracing is employed, where a scene is arranged into a bounding hierarchy, and cones are intersected with this hierarchy to compute an integration result through directional sampling, allowing for multi-pass global illumination and adaptive refinement based on variance and noise tolerance, reducing the number of samples needed and optimizing rendering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If Monte Carlo based ray tracing is used for global illumination, then realistic lighting and shadows can be achieved, but processing overhead increases and noise appears in rendered images

Engineering Contradiction:
Improverealistic lighting qualityVSAvoidprocessing overhead
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent segments the scene into a bounding hierarchy structure and divides the integration domain into cones. By organizing scene objects into hierarchical bounding volumes and processing integration in conical segments rather than random ray samples, the method reduces processing overhead while maintaining global illumination quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary organization of scene objects into a bounding hierarchy before rendering. This pre-processing step structures the scene data to enable efficient cone-based integration, avoiding the random access patterns of Monte Carlo methods and reducing processing overhead during actual rendering.

Inventive Principle:
Principle #10Preliminary action

2Illumination intensity

If Monte Carlo based ray tracing is used for global illumination, then realistic lighting can be achieved, but significant noise appears in rendered images especially at high resolutions

Engineering Contradiction:
Improverealistic lighting qualityVSAvoidimage noise level
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

By segmenting the integration domain into cones and processing each cone systematically, the method reduces the variance and noise inherent in random Monte Carlo sampling. The conical segmentation provides a structured approach to integrating radiance that produces cleaner images at high resolutions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the stochastic mechanical sampling process of Monte Carlo ray tracing with a deterministic integration approach using cones. This substitution eliminates the random noise characteristic of Monte Carlo methods while maintaining the physical accuracy of global illumination calculations.

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

3Area of stationary object

If conventional ray tracing is used for complex scenes, then complete scene coverage can be achieved, but processing time and computational resources increase significantly

Engineering Contradiction:
Improvescene coverageVSAvoidrendering efficiency
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The patent segments both the scene into bounding hierarchies and the integration domain into cones. This dual segmentation enables efficient traversal and processing, covering the entire scene while reducing the computational work required compared to conventional ray tracing methods.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

By pre-organizing the scene into a bounding hierarchy structure, the patent enables efficient spatial queries and cone intersections during rendering. This preliminary organization significantly reduces processing time for complex scenes while maintaining complete scene coverage.

Inventive Principle:
Principle #10Preliminary action

4Measurement precision

If Monte Carlo sampling is used to reduce noise, then more samples are required per pixel, but this increases processing overhead and rendering time

Engineering Contradiction:
Improvenoise reductionVSAvoidrendering speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces stochastic Monte Carlo sampling with deterministic cone-based integration. This substitution achieves noise reduction without requiring multiple samples per pixel, thereby maintaining rendering speed while improving image quality.

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

Solution Approach 2:

The cone structure acts as an intermediary between the scene and the integration process. By using cones as the integration domain instead of random rays, the method provides a structured approach that reduces noise inherently without requiring increased sampling, thus maintaining productivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2674918B1Integration cone tracing
Publication Date: 2019.11.06 DISNEY ENTERPRISES INC
  • EP2674918B1 patent drawingFigure 1
  • EP2674918B1 patent drawingFigure 2
  • EP2674918B1 patent drawingFigure 3A~3B

AI summary

A method is provided for integration cone tracing with particular application for feature films and other demanding content creation using scenes of high complexity requiring global illumination. Instead of using a conventional noise prone ray tracer, cones are intersected with a scene bounding hierarchy to determine intersecting scene geometry, and integration results are computed by directional sampling within the cones. As a result, the working data set may be reduced as the rendering may begin with a smaller set of cones as compared to the large number of rays required for acceptable filtering in a conventional ray tracer. Furthermore, by refining the cones during the rendering only on an as-needed basis according to an acceptable noise threshold and by sharing secondary cone bounces among primary cones, the processing workload and data set requirements may be kept to a reasonable level even for multiple global illumination passes.