Ray Tracing BVH Search for Instanced Object Detection
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Solution Overview
Problem
Existing ray tracing systems face challenges in efficiently performing object searches within a scene, particularly when dealing with instances and non-axis-aligned bounding volumes, which can lead to inefficient processing and resource utilization.
Innovation Solution
Adaptation of ray tracing hardware to utilize bounding volume hierarchies (BVHs) and Chebyshev distance metrics for object searching, incorporating instance transforms to accurately identify objects within a search area, and dynamically adjusting the search area based on found objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ray tracing hardware is adapted to perform object searches using BVHs and Chebyshev distance metrics, then search accuracy and efficiency are improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by adapting existing ray tracing hardware to perform both traditional ray tracing operations and object search operations. The same hardware components (shader cores, acceleration structure traversal units) are utilized for dual purposes, eliminating the need for separate dedicated search hardware while achieving improved search efficiency through BVH traversal and Chebyshev distance metrics.
Solution Approach 2:
The patent changes the distance metric parameter from traditional Euclidean distance to Chebyshev distance, which is naturally suited for axis-aligned bounding box operations in ray tracing hardware. This parameter change enables more efficient object search by leveraging the hardware's existing box-test capabilities and BVH structure, improving search performance without requiring fundamental hardware redesign.
2Measurement precision
If dynamic search area adjustment is implemented based on found objects, then search precision is improved, but processing time increases
Solution Approach 1:
The patent implements feedback by dynamically adjusting the search area based on objects found during traversal. When objects are identified within the current search area, the search area is updated to focus on regions of interest, providing feedback that refines subsequent search operations. This feedback mechanism improves identification accuracy while maintaining efficiency by avoiding unnecessary exploration of irrelevant regions.
Solution Approach 2:
The search area is made dynamic rather than static, allowing it to adapt during the traversal process. The search area expands or contracts based on the distribution and characteristics of found objects, enabling the system to respond to the actual scene content. This dynamic adjustment improves precision by focusing computational resources on relevant regions while minimizing time spent on irrelevant areas.
3Measurement precision
If instance transforms are used to accurately identify objects within search area, then search accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing instance transform matrices and their inverses during scene setup. These pre-computed transforms are then applied efficiently during object search without requiring complex real-time calculations. The BVH structure is also pre-built with transformed bounding boxes, allowing rapid traversal and object identification while maintaining high accuracy for instanced geometry.
Data Source
AI summary
It is often desirable to perform a search for objects in a scene. Specifically, it is useful to determine whether objects are located within a search area and/or to identify the nearest objects to a search point. Ray tracing systems have capabilities that are nearly sufficient to perform such a search. For instance, ray tracing systems build acceleration structures such as bounding volume hierarchies (“BVHs”) that help to accelerate the evaluation of a ray. These BVHs are also useful for performing object searches. Ray tracing hardware includes functionality related to performing a ray-box test, which can be adapted for searching whether an object is within a search area. Ray tracing hardware also includes functionality related to instances. In ray tracing, instances are copies of geometry, with an instance transform (e.g., scale, shear, rotation) applied. As objects being searched for may be instances, the instance-related functionality is useful for object searching.