Stable Ray Tracing via Temporal Hit Point Re-projection
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Solution Overview
Problem
Current ray tracing methods suffer from aliasing artifacts, particularly in regions with high-frequency content, due to insufficient sampling rates and temporal instability, leading to objectionable blurring and inconsistencies.
Innovation Solution
The method involves identifying old hit points from previous frames, re-projecting them into the current frame, adjusting samples based on criteria, tracing rays to determine new hit points, and reconstructing pixel colors, while reusing shading calculations and applying temporal anti-aliasing to achieve stable and high-quality image rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ray tracing is performed with sufficient sampling rate to capture high-frequency content, then aliasing artifacts are reduced, but computational complexity and rendering time increase significantly
Solution Approach 1:
The patent performs preliminary action by re-projecting hit points from previous frames before actual rendering. This pre-processing step identifies potential aliasing regions in advance, allowing the system to focus computational resources only on areas that require high-frequency sampling, thereby reducing overall computational complexity while maintaining sampling accuracy where needed.
Solution Approach 2:
The patent applies local quality by differentiating sampling strategies across different regions of the image. Instead of uniformly applying high sampling rates everywhere, the system adaptively adjusts sampling density based on local frequency content and motion characteristics, concentrating computational effort on regions with high-frequency content while using coarser sampling in stable areas.
2Stability of the object's composition
If temporal filtering is applied to reduce aliasing artifacts, then image stability improves, but blurring artifacts are introduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the blending factor between temporal and spatial sampling based on local image characteristics. In regions with high-frequency content or significant motion, the system reduces temporal blending to preserve sharpness, while in stable, low-frequency regions, it increases temporal blending to enhance stability and reduce aliasing.
Solution Approach 2:
The patent implements dynamics by making the filtering approach adaptive rather than static. The system continuously evaluates local image properties and motion vectors to determine the appropriate level of temporal filtering applied to each region, allowing the filtering strength to vary dynamically across space and time based on actual image content.
3Measurement precision
If high-frequency details are consistently sampled across frames, then aliasing artifacts are reduced, but rendering time increases due to additional computations
Solution Approach 1:
The patent applies copying by re-using hit point data and shading calculations from previous frames where applicable. Instead of重新 computing all ray intersections and shading operations, the system copies and re-projects valid hit points from prior frames, significantly reducing redundant computations while maintaining sampling consistency in stable regions.
Solution Approach 2:
The patent implements discarding and recovering by selectively discarding outdated or invalid hit points from previous frames and recovering only those that remain valid after re-projection. This selective approach eliminates the need to re-process all hit points while ensuring that valid sampling data is preserved and reused, optimizing the balance between sampling consistency and rendering efficiency.
Data Source
AI summary
A method, computer readable medium, and system are disclosed for performing stable ray tracing. The method includes the steps of identifying a plurality of old hit points used in a previously rendered frame, re-projecting the plurality of old hit points within a current frame to create a plurality of samples within a screen space of the current frame, adjusting the plurality of samples within the screen space of the current frame, based on one or more criteria, for each of the plurality of samples, tracing a ray from the sample toward a corresponding old hit point for the sample to determine a current hit point corresponding to the sample for the current frame, where the current hit point may include the corresponding old hit point for the sample or an updated hit point for the sample, shading at least a portion of the plurality of current hit points to obtain a color for each of the plurality of samples within the screen space of the current frame, and reconstructing a final color for a plurality of pixels in the screen space of the current frame, utilizing the color for each of the plurality of samples within the screen space of the current frame.