Adaptive Pixel Sampling for Temporal Rendering Artifacts

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Solution Overview

Problem

Current ray tracing techniques for computer-generated imagery face challenges in achieving high refresh rates and efficient rendering, particularly in real-time applications, due to limitations in spatial and temporal sampling rates, leading to artifacts like flickering and blurring.

Innovation Solution

The proposed solution involves a dynamic per-tile sampling order based on motion vectors, using techniques like hourglass and bowtie patterns to optimize pixel ordering, and combining subframes with prior frames to create full-resolution frames, reducing spatial and temporal aliasing effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If temporal antialiasing uses regular subpixel offsets and accumulates samples over many frames, then visual quality is improved, but rendering speed decreases and computational complexity increases

Engineering Contradiction:
Improvevisual qualityVSAvoidrendering speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies dynamics by making the sampling pattern adaptive rather than static. The system dynamically adjusts the sampling order based on motion vectors detected in the scene, switching between different sampling patterns (e.g., hourglass, bowtie) depending on the motion characteristics. This allows the system to optimize between visual quality and rendering speed in real-time based on actual scene content.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the sampling pattern parameter based on motion vector magnitude. When motion vectors indicate significant movement, the system switches to sampling patterns that better handle motion artifacts. This parameter adaptation allows the system to maintain visual quality while reducing the number of frames needed for accumulation, thereby improving rendering speed.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If ray tracing performs continuous updates of world simulation for each sample, then temporal resolution is improved, but computational complexity and rendering time increase

Engineering Contradiction:
Improvetemporal resolutionVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the pixel array into multiple tiles, each with its own sampling pattern. This segmentation allows different regions of the image to be processed independently with optimized sampling orders based on local motion characteristics. By dividing the large computational task into smaller tile-level operations, the system reduces overall computational complexity while maintaining high temporal resolution.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system applies partial action by selectively applying different sampling densities to different regions. Rather than uniformly sampling all pixels at maximum resolution, the system adjusts sampling intensity based on motion vector magnitude in each region, applying higher sampling rates only where motion indicates it is necessary for quality maintenance.

Inventive Principle:
Principle #16Partial or excessive action

3Ease of manufacture

If a fixed sampling pattern is used for all pixels, then implementation simplicity is maintained, but visual quality deteriorates due to aliasing and flickering

Engineering Contradiction:
Improveimplementation simplicityVSAvoidvisual quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements local quality by assigning different sampling patterns to different pixel regions based on their motion characteristics. Each tile or region receives a sampling pattern optimized for its specific motion vector properties, rather than applying a uniform pattern across the entire image. This significantly improves visual quality by reducing aliasing and flickering in motion-prone areas while maintaining implementation simplicity through systematic pattern assignment.

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS11997306B2Adaptive pixel sampling order for temporally dense rendering
Publication Date: 2024.05.28 NVIDIA CORP
  • US11997306B2 patent drawing
  • US11997306B2 patent drawing
  • US11997306B2 patent drawing

AI summary

A method dynamically selects one of a first sampling order and a second sampling order for a ray trace of pixels in a tile where the selection is based on a motion vector for the tile. The sampling order may be a bowtie pattern or an hourglass pattern.