Sparse voxel octree
Encyclopedia
A sparse voxel octree is a 3D computer graphics rendering technique using a raycasting or sometimes a ray tracing
approach into an octree
data representation.
The technique varies somewhat, but generally relies on generating and processing the hull of points (sparse voxel
s) which are visible or may be visible, given the resolution and size of the screen. The main points of the technique are: First, only pixels to be actually displayed need to be computed, with the actual screen resolution limiting the level of voxel detail required, and second, interior voxels – voxels fully enclosed by other voxels which are fully opaque – are unnecessary and thus need not be included in the 3D data set. The first point limits the computational cost during rendering, and the second point limits the amount of 3D voxel data (and thus storage space) required for realistic, high-resolution digital models and/or environments.
Because it needs only a small subset of the full voxel data a system does not need to process a massive amount of voxel data at any one time; it can extract data from extremely large data sources of voxels as and when needed. The basic advantage of octrees is that as a hierarchical data structure they need not be fully explored to their full depth, and this allows the system to run on current generation computer hardware. In addition, the octree datastructure permits smoothing of the underlying data, to help with antialiasing.
It is, however, a generally less well developed technique than standard polygon-based rasterisation
schemes.
Ray tracing
In computer graphics, ray tracing is a technique for generating an image by tracing the path of light through pixels in an image plane and simulating the effects of its encounters with virtual objects. The technique is capable of producing a very high degree of visual realism, usually higher than...
approach into an octree
Octree
An octree is a tree data structure in which each internal node has exactly eight children. Octrees are most often used to partition a three dimensional space by recursively subdividing it into eight octants. Octrees are the three-dimensional analog of quadtrees. The name is formed from oct + tree,...
data representation.
The technique varies somewhat, but generally relies on generating and processing the hull of points (sparse voxel
Voxel
A voxel is a volume element, representing a value on a regular grid in three dimensional space. This is analogous to a pixel, which represents 2D image data in a bitmap...
s) which are visible or may be visible, given the resolution and size of the screen. The main points of the technique are: First, only pixels to be actually displayed need to be computed, with the actual screen resolution limiting the level of voxel detail required, and second, interior voxels – voxels fully enclosed by other voxels which are fully opaque – are unnecessary and thus need not be included in the 3D data set. The first point limits the computational cost during rendering, and the second point limits the amount of 3D voxel data (and thus storage space) required for realistic, high-resolution digital models and/or environments.
Because it needs only a small subset of the full voxel data a system does not need to process a massive amount of voxel data at any one time; it can extract data from extremely large data sources of voxels as and when needed. The basic advantage of octrees is that as a hierarchical data structure they need not be fully explored to their full depth, and this allows the system to run on current generation computer hardware. In addition, the octree datastructure permits smoothing of the underlying data, to help with antialiasing.
It is, however, a generally less well developed technique than standard polygon-based rasterisation
Rasterisation
Rasterisation is the task of taking an image described in a vector graphics format and converting it into a raster image for output on a video display or printer, or for storage in a bitmap file format....
schemes.