GPU Displacement Ray Tracing with RMIP Bounding Prisms
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Solution Overview
Problem
Conventional scene rendering systems face challenges in efficiently rendering textured virtual objects due to the need for high-resolution geometry maintenance, large memory footprints, and limited execution performance, especially when dealing with complex displacement maps and dynamic texture displacement content.
Innovation Solution
The use of a rectangular minmax image pyramid (RMIP) data structure to provide displacement bounds for arbitrary axis-aligned rectangular regions in 2D texture space, combined with an iterative bound reduction process during ray tracing, allows for precise intersection prediction and reduced traversal steps, enhancing rendering speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scene rendering systems use high-resolution geometry to model textured surfaces, then rendering accuracy is improved, but memory footprint and device complexity increase
Solution Approach 1:
The patent extracts the displacement information from high-resolution geometry and stores it separately in a displacement map texture. This allows the actual geometry to remain low-resolution while the displacement map contains the detailed surface information needed for accurate rendering, thereby reducing memory footprint while maintaining rendering accuracy.
Solution Approach 2:
The patent uses a displacement map texture that copies displacement information from a reference texture to define surface geometry. This copying approach allows the system to represent complex surfaces without storing actual high-resolution geometry, reducing memory requirements while preserving rendering fidelity.
2Measurement precision
If conventional scene rendering systems maintain high-resolution geometry, then rendering accuracy is improved, but execution performance deteriorates
Solution Approach 1:
The patent replaces traditional geometric modeling mechanisms with a texture-based displacement mapping approach. Instead of using complex high-resolution mesh structures that require extensive processing, the system uses 2D texture maps with displacement values that can be evaluated efficiently during rendering, significantly improving execution performance while maintaining accuracy.
3Reliability
If conventional ray tracing processes traverse all bounding volumes, then completeness of intersection detection is improved, but rendering speed deteriorates
Solution Approach 1:
The patent performs preliminary computation of displacement bounds for each triangle in the mesh during preprocessing. These precomputed bounds are stored and used during ray tracing to quickly determine which triangles might be intersected by a ray, allowing the system to skip unnecessary intersection tests and significantly improve rendering speed while maintaining complete intersection detection.
4Ease of manufacture
If conventional methods use loose bounding volumes for displacement, then ease of implementation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent changes the parameters used to define displacement bounds from simple axis-aligned bounding boxes to more precise bounds based on the actual displacement map data. By computing minimum and maximum displacement values for each triangle and using these to define tighter bounding volumes, the system achieves both ease of implementation through systematic computation and improved bounds accuracy for better rendering precision.
Data Source
AI summary
A system generates, based on a displacement bounds data structure and a triangle mesh modeling a surface of a 3D virtual object within a 3D virtual scene, a displaced triangle mesh including one or more displaced surface bounding prisms, each of the one or more displaced surface bounding prisms displaced from a respective base triangle of a plurality of base triangles of the triangle mesh structure based on displacement bounds defined in a displacement bounds data structure for an area of a 2D texture space corresponding to a location of the respective base triangle defined by the 3D virtual scene. The system performs, using the displaced triangle mesh structure, a ray tracing process for a ray associated with a pixel of a 2D image of the virtual scene including determining, responsive to determining the ray intersects the particular displaced surface bounding prism, a location of an intersection of the ray.