Ray Tracing Shading Optimization for Memory Bandwidth
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Solution Overview
Problem
Current image rendering methods using rasterization technology in combination with ray tracing face challenges due to excessive memory bandwidth usage caused by frequent swapping of material information between memory and cache, especially when rendering three-dimensional scenes with multiple reflected objects sharing the same material information.
Innovation Solution
The proposed method involves a CPU dividing rendering information into that of reflective objects and reflected objects, allowing the GPU to perform ray tracing-based intersection calculations and shading separately for each material type, reducing the need for material information swapping by completing shading operations for all intersecting points corresponding to a specific material type before moving on to the next.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the GPU performs shading operations for each intersecting point successively using cached material information, then the rendering process can be completed, but the same material information is frequently swapped in and out between memory and cache, resulting in excessive memory bandwidth usage
Solution Approach 1:
The patent segments the rendering process into two distinct phases: an intersection calculation phase that identifies all intersecting points, and a shading phase that processes material information. By separating these phases, the system can cache material information more efficiently during the shading phase without the overhead of frequent swaps required in the traditional successive processing approach.
Solution Approach 2:
The patent performs intersection calculation in advance before the shading operation. By pre-identifying all intersecting points and their corresponding material information, the system prepares the data structure in advance, allowing the GPU to efficiently process shading operations with minimized memory access and reduced material information swapping during the actual rendering phase.
2Device complexity
If the GPU caches only one piece of material information at a time, then the cache size remains manageable, but material information must be frequently swapped between memory and cache when multiple reflected objects share the same material
Solution Approach 1:
The patent performs preliminary intersection calculation to group intersecting points by their corresponding material information. This pre-processing step creates an organized data structure that allows the GPU to load each unique material information piece into the cache once and process all associated intersecting points, eliminating the need for frequent cache swaps during the shading phase.
Solution Approach 2:
The patent changes the processing parameter from individual intersecting point processing to material-information-grouped processing. By organizing the rendering workflow around material information types rather than individual objects or intersecting points, the system can maintain material information in the cache for extended periods, reducing swap frequency while keeping cache size manageable.
Data Source
AI summary
An image rendering method in this application includes S1: performing ray tracing-based intersection calculation based on space information of a reflective object and space information of a reflected object to obtain M intersecting points on the reflected object, where the reflected object corresponds to at least one piece of material information, and M≥1; and S2: determining, in the M intersecting points, a plurality of intersecting points corresponding to target material information, and performing shading based on the target material information and space information of the plurality of intersecting points corresponding to the target material information, to obtain an image of a reflection that is of the reflected object and that is in the reflective object, where the target material information is the at least one piece of material information.