The advantage was the ability to rasterise using cheap integer calculations on a CPU without hardware acceleration.
There is a major downside to voxel rasterization when transformation is applied which causes severe aliasing. When a voxel is reached that has a higher y value on the display it is added to the y-buffer overriding the previous value and connected with the previous y-value on the screen interpolating the color values. A typical implementation will raytrace each pixel of the display starting at the bottom of the screen using what is known as a y-buffer.
The marching cubes algorithm is often used for isosurface extraction, however other methods exist as well.īoth ray tracing and ray casting, as well as rasterisation, can be applied to voxel data to obtain 2D raster graphics to depict on a monitor.Īnother technique for voxels involves raster graphics where one simply raytraces every pixel of the display into the scene, tracking an error term to determine when to step. Rendering Ī volume described as voxels can be visualized either by direct volume rendering or by the extraction of polygon iso-surfaces that follow the contours of given threshold values. The word voxel originated analogously to the word " pixel", with vo representing " volume" (instead of pixel's "picture") and el representing "element" a similar formation with el for "element" is the word " texel". Model set elements in this case are state parameters, indicating voxel belonging to the modeled object or its separate parts, including their surfaces. Yet, there is the simple form of record – indexes of the elements in the model set, i.e. If fixed voxel form is used within the whole model it is much easier to operate with voxel nodal points, i.e. One of the definitions is: "Voxel is an image of a three-dimensional space region limited by given sizes, which has its own nodal point coordinates in an accepted coordinate system, its own form, its own state parameter that indicates its belonging to some modeled object, and has properties of modeled region." This definition has the following advantage. For example, a cubic volumetric display might be able to show 512×512×512 (or about 134 million) voxels. Some volumetric displays use voxels to describe their resolution. Voxels are frequently used in the visualization and analysis of medical and scientific data (e.g. A direct consequence of this difference is that polygons can efficiently represent simple 3D structures with much empty or homogeneously filled space, while voxels excel at representing regularly sampled spaces that are non-homogeneously filled.
In contrast to pixels and voxels, polygons are often explicitly represented by the coordinates of their vertices (as points). Instead, rendering systems infer the position of a voxel based upon its position relative to other voxels (i.e., its position in the data structure that makes up a single volumetric image). coordinates) explicitly encoded with their values. As with pixels in a 2D bitmap, voxels themselves do not typically have their position (i.e. In 3D computer graphics, a voxel represents a value on a regular grid in three-dimensional space.