Methods and apparatus for imaging volume data with shading
US4835712A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 1986 |
| Grant date | May 30, 1989 |
| Priority date | — |
| Expiry date | Aug 15, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T17/00
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Method and apparatus for shading an image volume so that surfaces and boundaries may be rendered to subvoxel accuracy. A gradient vector is generated for each voxel of an image volume by calculating the change in opacity across that voxel in relation to its immediate neighbors. The gradient in the X, Y and Z direction of a three-dimensional voxel array is used to define a gradient length. By multiplying the RGBA values of individual voxels by their gradient length, a image volume may be shaded so that surfaces remain, but the interiors of solids are rendered more transparent revealing additional detail. Surfaces are shaded by multiplying the RGBA values of each voxel by a shading function. A reference point for a light source illuminating the displayed image volume is defined. A light vector is chosen for each voxel, a shading function is then generated based on the angle between the gradient vector and the light vector. The shading function allows for inputs for backlighting and side lighting.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.