Texture-Space Ray Tracing for Transparent Object Rendering
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Solution Overview
Problem
Existing methods for rendering transparent and translucent objects in computer graphics are inefficient, particularly in real-time applications like video games, as they either take too long or result in poor quality due to the complexity of sorting and blending surfaces.
Innovation Solution
A hybrid approach combining object-space ray tracing with texture-space parametrization and integration, where surface normal and world space coordinates are stored in textures, allowing for efficient ray tracing and lighting computation, and storing results in a texture map for final rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full ray tracing is used to render transparent or translucent objects, then rendering quality is improved, but rendering time increases significantly (from real-time to hours or days)
Solution Approach 1:
The patent segments the rendering process into two distinct phases: a preprocessing phase that computes and stores lighting information in textures (light maps), and a real-time phase that applies these precomputed textures during rendering. This segmentation allows the computationally intensive ray tracing to be performed only once during preprocessing, while real-time rendering simply samples the stored results, thus resolving the contradiction between high rendering quality and real-time performance
Solution Approach 2:
The patent performs preliminary ray tracing and lighting computation during an offline preprocessing stage, storing the results in light maps and other texture data structures. When real-time rendering is needed, the system simply applies these precomputed results without performing full ray tracing again. This preliminary action enables high-quality transparent and translucent object rendering to be achieved in real-time by reusing precomputed lighting information
2Productivity
If conventional blending methods are used to render transparent objects, then rendering speed is maintained, but rendering quality deteriorates due to incorrect occlusion and visibility
Solution Approach 1:
The patent introduces light maps as an intermediary data structure that stores precomputed lighting and visibility information for transparent and translucent objects. Instead of directly blending surfaces in real-time (which causes quality issues), the system uses these intermediary light maps to provide accurate occlusion and visibility data during real-time rendering, thus maintaining both speed and quality
Solution Approach 2:
The patent creates a copy of the lighting and visibility information in the form of light maps during preprocessing. These light maps are essentially copied representations of the complex ray-traced lighting data, which can be efficiently sampled and applied during real-time rendering without requiring the original computationally expensive ray tracing calculations, thus enabling fast rendering with high quality results
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables visually convincing and efficient rendering of transparent and translucent objects in real-time, handling refraction, light attenuation, and view-dependent lighting, suitable for video games and other performance-critical applications.
Implementation Method 1
determining a direction of a refraction vector at the location on the surface of the transparent object corresponding to the valid position value, wherein the direction of the refraction vector is based on a surface normal value at the location on the surface of the transparent object
Data Source
AI summary
Disclosed is a hybrid approach to rendering transparent or translucent objects, which combines object-space ray tracing with texture-space parametrization and integration. Transparent or translucent objects are first parameterized using two textures: (1) a texture that stores the surface normal at each location on the transparent or translucent object, and (2) a texture that stores the world space coordinates at each location on the transparent or translucent object. Ray tracing can then be used to streamline and unify the computation of light transport inside thick mediums, such as transparent or translucent objects, with the rest of the scene. For each valid (e.g., visible) location on the surface of a transparent or translucent object, the disclosed embodiments trace one or more rays through such objects and compute the resulting lighting in an order-independent fashion. The results are stored in a texture, which is then applied during the final lighting stage.