Ray Tracing Intersection Testing With Hierarchical Acceleration
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Solution Overview
Problem
Ray tracing systems face challenges in performing intersection testing at a rate suitable for real-time rendering, particularly on devices with tight constraints on silicon area, cost, and power consumption, such as mobile devices, due to the high processing demands and complexity of ray tracing algorithms.
Innovation Solution
A hierarchical acceleration structure is used with a serial-mode and parallel-mode ray processing approach, limiting the number of new ray requests generated during intersection testing to improve efficiency, and storing intersection information to manage memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hierarchical acceleration structure is used to reduce intersection testing work, then processing efficiency is improved, but memory usage increases due to storing acceleration structure data and intersection information
Solution Approach 1:
The patent implements a memory management system that discards intersection information when memory capacity is reached. The controller monitors memory usage and selectively removes older or less relevant intersection data to make space for new data, thereby maintaining the acceleration structure's benefits while preventing memory overflow on resource-constrained devices.
Solution Approach 2:
The system dynamically adjusts the amount of intersection information stored based on available memory capacity. When memory is full, the system changes the parameter of stored data by reducing the quantity of intersection information maintained, allowing the hierarchical acceleration structure to function effectively within tight memory constraints.
2Productivity
If ray tracing is performed with high processing power to achieve real-time rendering, then rendering speed is improved, but power consumption and silicon area increase
Solution Approach 1:
The patent segments the ray processing into parallel-mode and serial-mode operations. The parallel-mode handles ray requests that can be processed simultaneously, while serial-mode handles those requiring sequential processing. This segmentation allows the system to achieve real-time rendering performance on mobile devices by optimizing the distribution of processing tasks, thereby reducing overall power consumption and silicon area requirements.
3Measurement precision
If every ray is tested against every primitive to ensure accurate intersection detection, then measurement precision is improved, but processing time increases significantly
Solution Approach 1:
The patent constructs a hierarchical acceleration structure before performing ray intersection testing. This preliminary action organizes primitives into bounding volumes and groups them in a tree structure, allowing the system to quickly eliminate large portions of the scene that rays cannot intersect. This preprocessing step maintains intersection detection accuracy while dramatically reducing processing time by avoiding tests against every primitive.
4Productivity
If the number of new ray requests is limited in serial-mode processing to improve efficiency, then productivity is improved, but the complexity of managing ray request queues increases
Solution Approach 1:
The patent implements a controller that monitors the number of ray requests in queues and provides feedback to adjust processing modes. When the queue exceeds a threshold, the controller switches from parallel-mode to serial-mode processing, limiting new ray request generation. This feedback mechanism manages ray request complexity dynamically while maintaining processing efficiency on resource-constrained devices.
Data Source
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AI summary
A system and method for performing intersection testing of rays in a ray tracing system. The ray tracing system uses a hierarchical acceleration structure comprising a plurality of nodes, each identifying one or more elements able to be intersected by a ray. The system makes use of a serial-mode ray intersection process, in which, when a ray intersects a bounding volume, a limited number of new ray requests are generated.