Parallel Acceleration Structure Building for Faster Ray Tracing
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Solution Overview
Problem
Existing ray tracing systems face inefficiencies in the number of intersection tests required, particularly due to the complexity of object shapes, which can be addressed by using acceleration structures but still require improvements in computational efficiency.
Innovation Solution
A method of building acceleration structures in parallel using multiple threads, where elements of a scene are assigned to memory blocks and processed in parallel, utilizing levels-of-detail and hash functions to optimize node creation, and employing cache structures for efficient memory management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acceleration structures are used to reduce intersection tests, then rendering efficiency is improved, but memory usage and complexity of structure construction increase
Solution Approach 1:
The patent segments the acceleration structure construction process into multiple independent threads, where each thread builds a portion of the hierarchy (e.g., a subtree or region). This divides the complex construction task into manageable segments that can be executed in parallel, reducing overall construction time while maintaining the efficiency benefits of acceleration structures.
Solution Approach 2:
The patent performs preliminary actions by pre-allocating memory blocks and preparing scene elements before actual hierarchy construction. Threads are pre-configured with their assigned memory regions and scene element ranges, allowing them to immediately begin construction without synchronization overhead, thus improving rendering efficiency while managing complexity.
2Loss of time
If parallel processing is used to build acceleration structures, then construction time is reduced, but memory management complexity increases
Solution Approach 1:
Memory is segmented into distinct blocks assigned to different threads. Each thread operates within its allocated memory space, eliminating the need for complex inter-thread memory synchronization. This segmentation enables parallel construction while keeping memory management relatively simple through clear spatial separation.
Solution Approach 2:
Each thread has localized memory access patterns within its assigned block, creating local quality in memory usage. This locality reduces memory conflicts and simplifies management, as each thread independently manages its own memory region without needing to coordinate with other threads, thus reducing overall memory management complexity.
3Manufacturing precision
If more intersection tests are performed to handle complex object shapes, then rendering accuracy is improved, but computational efficiency deteriorates
Solution Approach 1:
The patent segments complex object shapes into simpler geometric primitives that form the leaves of the acceleration hierarchy. By representing complex objects as compositions of simpler shapes (e.g., triangles, boxes), the system maintains rendering accuracy while enabling efficient intersection tests against these simpler constituent shapes, thus improving computational efficiency.
Solution Approach 2:
The patent introduces the hierarchical dimension to the scene representation, organizing geometry into multi-level trees where complex objects are decomposed across multiple levels. This dimensional organization allows intersection tests to first check simple bounding volumes at upper levels before examining detailed geometry at lower levels, maintaining accuracy while dramatically improving efficiency by early-rejecting non-intersecting rays.
Data Source
AI summary
A computer implemented method of building an acceleration structure for use in ray tracing includes (i) assigning, in a memory, a different one or more blocks of memory to each of a plurality of threads, each of the blocks of memory comprising one or more memory locations; (ii) for each element of a plurality of elements of a scene for which nodes of the acceleration structure are to be built, assigning that element of the scene to a block of memory so as to assign that element to a thread; and (iii) building one or more nodes of the acceleration structure by processing each of the plurality of threads in parallel.