Hierarchical Presence Indication Blocks for Alpha-Tested Ray Tracing
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Solution Overview
Problem
Existing ray tracing systems experience significant latency and power consumption due to the frequent execution of shader programs to determine the presence of punch through primitives during intersection testing, which is exacerbated by the use of sub-primitives for complex shapes with alpha-tested textures.
Innovation Solution
A hierarchical encoding approach is employed to compress and decompress sub-primitive presence indications, utilizing parent-level and child-level data to efficiently represent the presence states of sub-primitives, reducing the need for shader program execution by leveraging the non-random distribution of presence states within the scene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sub-primitives are used to represent complex shapes with alpha-tested textures, then rendering quality is improved, but the number of shader program executions increases, causing increased latency and power consumption
Solution Approach 1:
The primitive is divided into multiple sub-primitives, and the presence indication block is segmented into corresponding sub-primitive presence indications. This segmentation allows the system to determine presence states for individual sub-primitives without executing shader programs for all sub-primitives, thereby reducing latency while maintaining rendering quality through selective alpha testing.
Solution Approach 2:
The patent pre-calculates and stores presence indications for each sub-primitive in a compressed block structure before rendering. This preliminary action enables the ray tracing system to quickly query presence states during intersection testing without performing time-consuming shader executions, thus reducing latency while preserving rendering quality.
2Manufacturing precision
If sub-primitives are used to represent complex shapes with alpha-tested textures, then rendering quality is improved, but power consumption increases due to frequent shader program execution
Solution Approach 1:
By segmenting the presence indication block into sub-primitive level indications, the system can selectively evaluate only those sub-primitives that require alpha testing. This segmentation reduces the frequency of shader program executions, thereby lowering power consumption while maintaining rendering quality for complex shapes with transparent regions.
Solution Approach 2:
The patent creates a compressed copy of presence information in a hierarchical block structure that can be quickly queried during ray tracing. This copy allows the system to determine sub-primitive presence states without repeatedly executing expensive shader programs, reducing power consumption while preserving rendering quality.
3Productivity
If compressed data structures are used to reduce memory bandwidth, then system performance is improved, but decompression complexity increases
Solution Approach 1:
The presence indication block is organized in a nested hierarchical structure where blocks are divided into sub-blocks, which are further divided into quarters. This nesting allows the decompression process to selectively traverse only the necessary levels of the hierarchy based on the ray's intersection path, improving system performance while managing decompression complexity through efficient selective expansion.
Solution Approach 2:
The compressed data structure applies different levels of detail to different regions of the presence indication block. Regions with uniform presence states are compressed more aggressively, while regions requiring fine-grained alpha testing maintain higher detail. This local quality approach improves overall system performance by reducing memory bandwidth requirements while keeping decompression complexity manageable through region-specific processing.
Data Source
AI summary
Compressed data is decompressed to determine one or more sub-primitive presence indications for use in a rendering system. It is determined whether child-level data is included in a hierarchical representation for a parent region in a block of compressed data for a block of sub-primitive presence indications subdivided into a plurality of parent regions, each subdivided into a plurality of child regions, where the block comprises the hierarchical representation of the block of sub-primitive presence indications, wherein for each of parent regions whose child regions all have the same presence state, parent-level data is included in the hierarchical representation to represent the presence state of the parent region without child-level data for the child regions within the parent region being included in the hierarchical representation. Where child-level data is not included in the hierarchical representation for the parent region, parent-level data for the parent region is used without child-level data, to determine one or more sub-primitive presence indications in the parent region.