Method of volume rendering for visualization three-dimensional data in x-ray computed tomography

The article is devoted to the method of producing three-dimensional images of objects - volume rendering, in relation to the X-ray computed tomography. The detailed description of the algorithm of volume rendering is close to implementation. The general principles of the algorithm of volume rendering three-dimensional arrays of voxel data are described. The mechanism of blowing rays in three-dimensional space through the volumetric data set, including setting the observation plane, viewing angle, zooming in implementing parallel projection, is given. We consider sample points along the ray started up in his parametric assignment, as well as taking a step sampling points according to the sampling theorem. Trilinear interpolation to obtain values that do not fall into the three-dimensional mesh nodes of the volumetric dataset is described. We describe the use of transfer functions to set the color and transparency visualize structures. The model of Phong lighting and the associated calculation of gradient of the three-dimensional data is considered. An alternative method for shading a three-dimensional image based on the light attenuation equation and does not require the computation of gradient of the data is given. A compositing on the basis of the fundamental equation of volume rendering as a way to obtain a image of the three-dimensional object by the method of volume rendering is obtained.