MegaTexture
MegaTexture , also called Mega-Texture , describes a technique of texture allocation that makes it easier to use a single, large texture to cover a virtual terrain.
Current games, such as a. also Crysis , mainly use smaller, repetitive texture tiles to texturize a terrain . These textures are rarely larger than 2048 × 2048 pixels . The current version of MegaTexture, which was developed by id Software’s former Technical Director John Carmack , and was first introduced to the masses in Splash Damage's game Enemy Territory: Quake Wars , uses textures up to 32,000 × 32,000 pixels to represent the terrain.
technology
The MegaTexture technology is actually an implementation of clip mapping , also called ClipTexture , which was developed by Silicon Graphics in the mid-1990s.
Since the MegaTexture uses a large single texture for the static structure of a terrain, it is very data-intensive, since it does not rely on repetitive textures. Texture streaming is used to master the large amount of data . The texture is saved on a removable storage medium or a hard drive and loaded if necessary in order to enable large amounts of detail and variation over a large area with comparatively little use of RAM .
During the rendering process , the required parts of the texture are scaled to the corresponding mip-mapping level, which depends on the polygon size, and loaded into the assigned texture memory of the video memory. This procedure allows the engine to keep the number of texels , the texture pixels, in the VRAM low.
Future development
introduction
Id has already presented a more advanced technique, which is based on the MegaTexture idea and virtualizes both geometry and textures in order to obtain unique geometries up to the equivalent of the Texel ( Sparse Voxel Octree (SVO)). This technology could potentially be used in id Tech 6 .
This works by raycasting a geometry represented by voxels instead of polygons . The aim is to stream parts of the octree into the video memory and thus increase the complexity of the geometry in such a way that even at close range a level of detail that has never been achieved before is created. The geometry details that can be represented with this method are almost infinite, which makes it unnecessary to simulate 3D details with techniques such as normal mapping .
Although most voxel tests require large amounts of memory (up to several gigabytes), id Software's Jon Olick believes it is possible to compress the SVOs to 1.15 bits per voxel of position data.
Virtual texturing
The id software game Rage , equipped with the id Tech 5 engine, uses an advanced technique called virtual texturing . Textures can be 128,000 × 128,000 pixels and larger and are not only used for terrain, but also for models and sprites, among other things.
Web links
- id software
- Splash Damage
- Arnout van Meer on Quake Wars
- Sparse Virtual Textures by Sean Barrett, a related technique with more technical explanations ( video demonstration ; AVI ; 144 MB).
Individual evidence
- ↑ http://s09.idav.ucdavis.edu/talks/05-JP_id_Tech_5_Challenges.pdf From Texture Virtualization to Massive Parallelization
- ↑ Archived copy ( Memento of the original from October 15, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Id Tech 5 stage demo
