Triangle Visibility Masks for Real-Time Ray Tracing Traversal
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Solution Overview
Problem
Existing ray tracing technologies face challenges in achieving real-time interactive performance due to the computational intensity of testing rays against complex 3D scenes, particularly in determining visibility and handling transparent or translucent objects, which leads to performance loss and resource inefficiency.
Innovation Solution
Implementing a hardware-accelerated ray tracing coprocessor with visibility masks (VMs) that allow for inline visibility tests within the coprocessor, reducing the need for processor intervention by using micro-meshes and barycentric coordinates to determine the visibility status of ray-primitive intersections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ray tracing algorithms are used to test rays against complex 3D scenes, then visibility determination is achieved, but computational intensity increases and real-time interactive performance is not achieved
Solution Approach 1:
The patent segments the geometric primitive into multiple micro-meshes, where each micro-mesh represents a small region of the primitive. This segmentation allows the visibility status to be determined locally for each micro-mesh containing the intersection point, rather than performing complex global visibility tests. The segmented approach reduces computational intensity while maintaining visibility determination accuracy.
Solution Approach 2:
The patent pre-computes and stores visibility masks for each micro-mesh during an offline preparation phase. These visibility masks encode the visibility status (visible, partially visible, or occluded) for each micro-mesh relative to different viewing directions. During real-time ray tracing, the pre-computed visibility masks are directly queried using barycentric coordinates, eliminating the need for complex runtime visibility tests and enabling real-time interactive performance.
2Measurement precision
If processor intervention is used for visibility tests, then accurate visibility status is determined, but resource efficiency decreases and performance is reduced
Solution Approach 1:
The patent implements self-service by encoding all necessary visibility information directly into the micro-mesh data structure and visibility masks. When a ray intersects a geometric primitive, the intersection point's barycentric coordinates directly index into the pre-computed visibility mask of the containing micro-mesh, providing the visibility status without requiring any processor intervention or additional visibility tests. The data structure serves itself by containing all needed information inline.
Solution Approach 2:
The patent creates simplified copies of visibility information in the form of visibility masks that are stored with each micro-mesh. These masks are compact representations of complex visibility relationships, allowing rapid querying during ray tracing. Instead of performing complex visibility tests, the system queries these pre-computed copies, dramatically reducing processor resource consumption while maintaining accuracy.
3Manufacturing precision
If complex visibility tests are performed for transparent or translucent objects, then accurate rendering is achieved, but thread divergence increases and performance is lost
Solution Approach 1:
The patent applies local quality by determining visibility status independently for each micro-mesh containing an intersection point, rather than performing uniform complex tests across all primitives. Each micro-mesh has its own pre-computed visibility mask tailored to its specific geometry and occlusion relationships. This localized approach allows transparent and translucent objects to be handled efficiently with simple mask queries, reducing thread divergence while maintaining rendering accuracy.
Data Source
AI summary
Techniques applicable to a ray tracing hardware accelerator for traversing a hierarchical acceleration structure with reduced round-trip communications with a processor are disclosed. The reduction of round-trip communications with a processor during traversal is achieved by having a visibility mask that defines visibility states for regions within a geometric primitive available to be accessed in the ray tracing hardware accelerator when a ray intersection is detected for the geometric primitive.