Multi-Volume Rendering With Efficient Overlap Compositing
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Solution Overview
Problem
Existing technologies face challenges in efficiently performing direct multi-volume rendering for three-dimensional scenes, particularly when volumes overlap, as they often rely on inefficient ray marching techniques that do not directly compute intersections with 3D object surfaces.
Innovation Solution
A computer-implemented method and system (MVR) for direct multi-volume rendering, utilizing a multi-ray generator, volume ray marching processor, and projection image updater to process individual view rays within associated volumes, applying transfer functions for color and transparency mapping, and optimizing processing through parallelization and empty-space skipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional volume ray marching is used for multi-volume rendering, then the rendering process can handle overlapping volumes, but the computational efficiency deteriorates due to inefficient ray marching techniques that do not directly compute intersections with 3D object surfaces
Solution Approach 1:
The patent divides the multi-volume rendering process into separate processing stages: surface intersection computation for each volume, followed by compositing of results. Each volume is processed independently to compute ray-surface intersections, then the results are combined. This segmentation allows efficient handling of overlapping volumes while maintaining computational tractability.
Solution Approach 2:
The patent performs preliminary surface intersection computations for each volume before compositing. By pre-computing which surfaces intersect with each ray and organizing this information in advance, the system avoids redundant calculations during the final compositing stage, significantly improving computational efficiency for multi-volume scenes.
2Manufacturing precision
If small ray marching steps are performed to sample voxels accurately, then the rendering precision improves, but the processing time increases
Solution Approach 1:
The patent replaces the traditional mechanical ray marching approach (stepping through voxels) with a mathematical surface intersection computation method. Instead of incrementally sampling along rays, the system directly computes where rays intersect with isosurfaces extracted from the volumetric data, achieving high precision without the time cost of fine-stepped ray marching.
Solution Approach 2:
The patent changes the fundamental parameter of ray traversal from discrete step size to continuous surface intersection parameters. By working with surface geometry parameters rather than voxel grid parameters, the system achieves rendering precision independent of sampling density, eliminating the trade-off between precision and processing time.
Data Source
AI summary
For direct multi-volume rendering, each voxel of a volume has a scalar value. A multi-ray generator generates a view multi-ray in the direction of a pixel of a projection image, wherein the pixel represents a 2D projection of all scene voxels intersecting with the view multi-ray behind the projection image. A volume ray marching processor processes each view ray, wherein, at each ray marching step, the scalar value of the corresponding voxel is mapped to a color value and a transparency value of said corresponding voxel. A projection image updater updates the value of the particular pixel in the projection image by combining the respective voxel color and transparency values of the individual view rays. Updating with the values of a particular voxel intersecting with a particular view ray is performed after the updating with all intersecting voxel values of voxels closer to the viewing point than the particular voxel.