Low Discrepancy Sequence Subset Generation for Photon Mapping

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Solution Overview

Problem

Current photon mapping techniques suffer from approximation artifacts that affect the visual realism of generated images, particularly due to clustering and averaging methods.

Innovation Solution

A system and method for generating a subset of a low discrepancy sequence by identifying a low discrepancy sequence, determining a threshold value, and selecting a single dimension for comparison, resulting in a subset with reduced dimensions while maintaining low discrepancy properties, which can be applied in photon mapping to improve image generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If clustering and averaging methods are used in photon mapping, then computational efficiency is improved, but approximation artifacts are introduced that reduce image quality

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidimage quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent extracts only the necessary elements from the full low discrepancy sequence by applying a threshold criterion to select a subset of photons. This extraction approach eliminates the need for clustering and averaging operations that cause approximation artifacts, while maintaining computational efficiency by working with a reduced set of carefully selected photons that preserve the low discrepancy properties needed for high-quality rendering.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the selection criterion from spatial clustering to a threshold-based parameter comparison. By comparing each photon's contribution parameter against a threshold value derived from the low discrepancy sequence, the method selects photons that meet a minimum quality criterion without requiring clustering operations, thus eliminating approximation artifacts while maintaining computational efficiency.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If a full low discrepancy sequence is used in photon mapping, then image quality is improved, but computational cost increases

Engineering Contradiction:
Improveimage qualityVSAvoidcomputational efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent extracts a subset of photons from the full low discrepancy sequence by applying a threshold criterion. This extraction maintains the low discrepancy properties necessary for high-quality rendering while reducing the total number of photons processed, thereby improving computational efficiency without sacrificing image quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by selecting only the necessary portion of the low discrepancy sequence that meets the threshold criterion. Rather than processing the entire sequence, the method uses a carefully selected subset that provides sufficient coverage and quality for the rendering task, achieving the desired image quality with reduced computational cost.

Inventive Principle:
Principle #16Partial or excessive action

3Speed

If clustering is performed to reduce computational load, then processing speed is improved, but approximation artifacts are introduced

Engineering Contradiction:
Improveprocessing speedVSAvoidvisual realism
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The patent replaces clustering with a direct extraction approach using threshold comparison. By extracting photons that meet the threshold criterion from the low discrepancy sequence, the method achieves processing speed improvements without the approximation artifacts introduced by clustering, as each selected photon maintains its individual contribution to the final image.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent inverts the traditional approach by not grouping photons together (clustering) but instead selecting individual photons that meet a quality threshold. This inversion of the clustering concept—selecting based on individual merit rather than group properties—eliminates approximation artifacts while maintaining processing efficiency through the reduced subset size.

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentUS9202139B2System, method, and computer program product for generating a subset of a low discrepancy sequence
Publication Date: 2015.12.01 NVIDIA CORP
  • US9202139B2 patent drawing
  • US9202139B2 patent drawing
  • US9202139B2 patent drawing

AI summary

A system, method, and computer program product are provided for generating a subset of a low discrepancy sequence. In use, a low discrepancy sequence is identified. Additionally, a threshold value is determined. Further, a single dimension of the low discrepancy sequence is selected. Further still, for each element included within the low discrepancy sequence, the selected single dimension is compared to the determined threshold value. Also, a subset of the low discrepancy sequence is generated, based on the comparing.