Ray Packet Processing for SIMD Ray Tracing Coherency
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Solution Overview
Problem
Conventional SIMD acceleration algorithms for ray tracing primarily focus on primary rays and fail to efficiently handle secondary rays with high coherency, leading to performance degradation as the number of rays increases, especially with the limited bandwidth of current hardware.
Innovation Solution
A data processing apparatus and method that utilizes a SIMD-type processor to generate packets for both primary and secondary rays, employing a spatial data structure like a kd-tree or BVH, and applying breadth-first and depth-first search algorithms to determine child and grandchild nodes, thereby improving collision checks and maintaining performance with increasing SIMD bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If SIMD acceleration algorithms are based only on primary rays, then primary ray processing is efficient, but secondary ray processing performance deteriorates due to loss of coherency
Solution Approach 1:
The patent segments rays into packets of k rays (where k is a natural number) and processes them in groups through multiple stages. This segmentation allows the system to maintain coherency within each packet while processing diverse ray types (primary and secondary rays) through the same SIMD pipeline, resolving the contradiction between processing efficiency and coherency maintenance.
Solution Approach 2:
The patent dynamically adapts the packet structure and processing stages based on ray coherency characteristics. By using multiple processing stages with conditional packet generation and dynamic ray traversal control, the system maintains optimal performance for both primary rays (high coherency) and secondary rays (lower coherency), preventing performance deterioration.
2Speed
If the number of SIMD bits is increased to improve processing capacity, then computational speed improves, but performance degrades due to ray coherency issues
Solution Approach 1:
The patent introduces a multi-stage processing dimension beyond simple SIMD bit width expansion. By organizing processing into multiple stages with packet-based ray groups and conditional traversal, the system effectively utilizes increased SIMD bandwidth while maintaining coherency through structured data organization and processing flow control.
Solution Approach 2:
The patent changes the parameter of ray organization from individual ray processing to packet-based processing with k rays per packet. This parameter change allows the system to fully utilize increased SIMD bit width while maintaining coherency through controlled packet generation and multi-stage processing, preventing the performance degradation that would otherwise occur with higher bandwidth hardware.
3Ease of manufacture
If conventional SIMD algorithms are used for all rays, then implementation is simple, but performance degrades with increasing number of rays due to coherency loss
Solution Approach 1:
The patent segments the ray processing into multiple stages with packet-based organization. This segmentation maintains implementation simplicity by using structured, repeatable processing blocks while enabling better scaling performance through efficient utilization of SIMD bandwidth and maintained coherency within packets, even as the total number of rays increases.
Solution Approach 2:
The patent performs preliminary actions by organizing rays into packets before SIMD processing and preparing multiple processing stages in advance. This preliminary organization maintains implementation simplicity through structured data preparation while enabling better scaling performance by ensuring coherency is maintained throughout the processing pipeline as ray counts increase.
Data Source
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AI summary
A data processing apparatus for a collision check with respect to a plurality of rays. A control unit may generate a plurality of packets with respect to a plurality of rays associated with a first node in a spatial data structure. At least one of the plurality of packets may include information about k rays, and k may be a natural number. A processor may sequentially receive the plurality of packets and determine which child node of the first node is associated with each of the plurality of rays associated with the first node.