Photon Map Rendering of Translucent Objects With Subsurface Scattering
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Solution Overview
Problem
Current computer graphics systems struggle to realistically render translucent objects due to computational limitations, particularly in accounting for subsurface scattering, which is not effectively addressed by existing direct light models that often render these objects as opaque.
Innovation Solution
The proposed solution modifies existing direct light models to incorporate subsurface scattering effects using a photon map to estimate the contribution of scattered light, allowing for efficient rendering of translucent objects by calculating the color contribution from nearby points and light sources, thereby enhancing the realism of image rendering without excessive computational overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ray tracing is used to account for indirect light and subsurface scattering, then rendering quality is improved, but computational cost increases significantly
Solution Approach 1:
The patent pre-calculates and stores light transport information in a photon map during an offline processing stage. This photon map is then reused during the rendering process, eliminating the need for expensive real-time ray tracing while maintaining accurate subsurface scattering effects.
Solution Approach 2:
The patent creates a simplified data structure (photon map) that copies and pre-processes light transport information from complex ray tracing calculations. This copied data can be efficiently queried during rendering without performing the full ray tracing computation again.
2Use of energy by moving object
If standard direct light models are used, then computational cost is reduced, but rendering accuracy deteriorates for translucent objects
Solution Approach 1:
The patent introduces a photon map as an intermediary data structure that bridges the gap between simple direct light models and complex ray tracing. This intermediary stores pre-computed light transport information, allowing the system to use efficient direct light rendering while achieving accurate translucent object representation through subsurface scattering corrections.
3Manufacturing precision
If ray tracing is performed for all objects in a scene, then lighting accuracy is improved, but processing time increases significantly
Solution Approach 1:
The patent performs complex light transport calculations in advance during an offline processing stage, storing the results in a photon map. During actual rendering, the system only needs to query this pre-computed data, dramatically reducing processing time while maintaining lighting accuracy.
Solution Approach 2:
The patent separates the rendering process into two distinct stages: an offline processing stage where complex light transport is pre-computed and stored in the photon map, and an online rendering stage where only simple queries to the photon map are performed. This segmentation allows accurate lighting to be achieved without the time cost of real-time ray tracing.
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
This approach enables realistic rendering of translucent objects with reduced computational requirements, effectively addressing the limitations of existing systems by incorporating subsurface scattering into the rendering process, resulting in more accurate and aesthetically compelling visuals.
Implementation Method 1
Subsurface scattering refers to the fact that the color of a particular point in a translucent object is often related to the illumination received by other proximate points
Data Source
AI summary
Embodiments are directed to modifying an existing scheme for providing translucent illumination in order to take account of subsurface scattering. The color of a selected point of a translucent object can be determined using existing methods. The existing methods need not take subsurface scattering into account. Then, a contribution to the color at the selected point due to subsurface scattering may be calculated. The contribution due to subsurface scattering may be calculated based on a photon map. Embodiments of the invention also include the use of different types of photon maps. In some embodiments, a standard photon map may be used. In other embodiments, a photon map may be defined in a manner similar to a depth map. Thus, the entries of a photon map may be defined in terms of an angle from a light source and a distance between an object's surface and a light source.