Hierarchical Sub-Primitive Encoding for Faster Ray Tracing
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Solution Overview
Problem
Existing ray tracing systems experience latency and increased computational load due to frequent execution of shader programs to determine the presence of punch through primitives during intersection testing, which is exacerbated by the use of sub-divided primitives for complex shapes.
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 state of sub-primitives, reducing the need for shader program execution during intersection testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sub-divided primitives are used to represent complex shapes, then the accuracy of geometric representation is improved, but the computational load and latency increase due to frequent shader program executions
Solution Approach 1:
The patent pre-calculates and stores presence indications for each sub-primitive in a hierarchical data structure before ray tracing begins. This preliminary action allows the system to quickly determine whether sub-primitives are present or absent during intersection testing, avoiding the need to execute shader programs at runtime and thus reducing latency while maintaining geometric accuracy
Solution Approach 2:
The patent creates a compressed copy of the presence indication data in a hierarchical structure that can be efficiently queried during ray tracing. Instead of storing full geometric data or executing complex shader programs, the system uses a simplified data representation that captures the essential presence/absence information, reducing computational load while preserving the ability to accurately represent complex shapes
2Ease of operation
If sub-primitive presence indications are stored in uncompressed format, then the ease of access to presence data is improved, but the memory bandwidth and processing overhead increase
Solution Approach 1:
The patent segments the presence indication data into a hierarchical structure with parent and child nodes, where each node represents a group of sub-primitives. This segmentation allows the system to store data in a compressed format while maintaining efficient access patterns, as the hierarchical structure enables quick navigation to relevant data regions without requiring decompression of the entire dataset
Solution Approach 2:
The patent implements a nested hierarchical structure where parent nodes contain presence indications for groups of child nodes, which in turn contain presence indications for smaller groups. This nesting allows for progressive refinement of presence information, enabling the system to access data at the appropriate level of detail without processing the full uncompressed dataset, thus reducing memory bandwidth requirements while maintaining data accessibility
3Measurement precision
If shader programs are executed frequently to determine primitive presence, then the accuracy of intersection testing is improved, but the power consumption and latency increase
Solution Approach 1:
The patent extracts the essential presence information from the full geometric data and stores it separately in a compressed hierarchical structure. By taking out only the critical presence/absence indications and storing them in an optimized format, the system can quickly determine whether shader program execution is necessary, thereby maintaining intersection testing accuracy while significantly reducing the frequency of shader executions and associated latency
Solution Approach 2:
The patent introduces a compressed presence indication data structure as an intermediary between the geometric data and the shader programs. This intermediary layer allows the system to quickly query presence information without invoking complex shader programs, maintaining measurement precision by providing accurate presence data while reducing latency by avoiding frequent shader executions
4Quantity of substance
If hierarchical encoding is used to compress presence data, then the data storage efficiency is improved, but the complexity of data processing increases
Solution Approach 1:
The patent segments the compression and decompression operations into discrete hierarchical levels, where each level processes only the data relevant to its parent and child nodes. This segmentation reduces the complexity of individual processing steps, as each node only needs to handle a manageable subset of the total data, while still achieving overall data storage efficiency through the hierarchical structure
Data Source
AI summary
Compressed data is decompressed to determine sub-primitive presence indications in a rendering system. A received compressed block of sub-primitive presence indications is subdivided into a plurality of parent regions, each subdivided into a plurality of child regions. A hierarchical representation of the block of sub-primitive presence indications is provided, wherein: (i) for each parent region whose child regions all have the same presence state, parent-level data is included 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, and (ii) for each parent region whose child regions do not all have the same presence state, child-level data for the child regions within the parent region is included in the hierarchical representation to represent the presence states for the child regions within the parent region. If child-level data is included in the hierarchical representation, child-level data for said one of the parent regions is used to determine one or more sub-primitive presence indications in the parent region. If child-level data is not included in the hierarchical representation, parent-level data is used, without child-level data, to determine one or more sub-primitive presence indications in the parent region.