Flexible Scale Rasterization for Shadow Map Rendering
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Solution Overview
Problem
Conventional image rendering techniques, such as foveated rendering, face inefficiencies in shadow map rendering due to lower resolution shadow maps and varying texel contributions, leading to reduced performance and quality, especially when resources are limited.
Innovation Solution
The implementation of flexible scale rasterization (FSR) adjusts shadow map rendering by using FSR x and y curves to prioritize texel distribution based on image visibility, ensuring higher resolution where needed and maintaining quality while reducing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If foveated rendering is applied to reduce computational cost in peripheral regions, then processing resources are reduced, but shadow map quality and texel distribution uniformity deteriorate
Solution Approach 1:
The patent applies different rendering qualities to different regions of the shadow map by using FSR curves to create non-uniform texel distributions. High-resolution rendering is concentrated in regions corresponding to the fovea (central vision), while peripheral regions use lower resolution, matching human visual perception characteristics and reducing unnecessary computational resources in areas less critical to perceived quality.
Solution Approach 2:
The patent dynamically adjusts the shadow map resolution and texel distribution based on the FSR curves, which are updated according to the current view frustum and shadow receiving geometry. This allows the rendering system to adaptively allocate resources to the most visually important regions while maintaining overall shadow map quality where needed.
2Manufacturing precision
If uniform resolution is used across the entire shadow map, then shadow quality is maintained consistently, but computational cost and resource usage increase
Solution Approach 1:
Instead of applying uniform resolution across the entire shadow map, the patent uses FSR curves to create a non-uniform texel distribution that concentrates high-resolution rendering in regions where shadows are most visible and important (corresponding to foveal vision areas), while using lower resolution in peripheral regions, thereby reducing overall computational cost while maintaining perceived quality.
Solution Approach 2:
The patent changes the resolution parameter of the shadow map dynamically by using FSR curves to define variable texel densities across different regions. This allows the system to adjust local resolution based on visual importance, transforming the fixed uniform resolution approach into a variable resolution system that optimizes the balance between quality and performance.
3Manufacturing precision
If high resolution shadow maps are rendered across all regions, then shadow quality is maximized, but memory usage and processing time increase
Solution Approach 1:
The patent reduces memory usage by rendering shadow maps with non-uniform resolution using FSR curves. High-resolution texels are allocated only to regions where shadows are most critical (foveal regions), while peripheral regions use lower resolution, significantly reducing the total number of texels required in the shadow map texture memory.
Solution Approach 2:
The patent applies high-resolution rendering only partially, specifically to the regions of the shadow map that correspond to foveal vision areas where shadow quality is most critical. Peripheral regions receive reduced resolution, eliminating excessive resource allocation to areas that contribute less to perceived quality, thereby optimizing memory usage.
Data Source
AI summary
A shadow rendering method for an image includes: re-projecting 3D coordinates of image pixels from an image space of the image to points on a 2D shadowmap space; estimating at least one of a horizontal and vertical distribution of the points in the shadow map space; for a flexible scale rasteriser ‘FSR’, updating a horizontal or vertical FSR curve corresponding to a distribution of FSR bins for the shadow map so that the corresponding horizontal or vertical distribution of points per bin is most even; and rendering the shadow map using flexible scale rasterization.