MegaTexture

Mega Texture, mega - texture refers to a technique of texture allocation that makes it easier to refer to a single large texture for covering a virtual terrain.

Introduction

Recent games such as, but also Crysis, use mostly small repetitive textures tiles for texturing a terrain. These textures are rarely larger than 2048 × 2048 pixels. The current version of the Mega Texture, which was developed by id Software technical director John Carmack, and the first time in Splash Damages game Enemy Territory: was presented Quake Wars the mass audience uses up to 32000 × 32000 pixels large textures for the terrain.

Technology

The Mega Texture technology is actually an implementation of the clip mapping, also called Texture clip, which was developed by Silicon Graphics in the mid-1990s.

Since the Mega Texture uses a large single texture for the static structure of a site it is very data- intensive, as is not set here on repetitive textures. In order to meet the large data volume Lord, one uses the Texturestreaming. The texture is stored on a removable disk or a hard disk and loaded on demand, so as to allow large amounts of detail and variation over a large area with relatively low memory usage.

During rendering this, the required portions of the texture, scaled to the appropriate mip- mapping level which is dependent on the size of the polygon is loaded into the texture memory allocated to the video memory. This procedure allows the engine the number of texels of the texture pixels to minimize the VRAM.

Future Development

Introduction

Id has already presented a more advanced technique, which is based on the Megatexture idea and virtualizes both geometry and textures to this kind of unique geometry up to the equivalent of the texel to obtain ( Sparse Voxel Octree ( SVO) ). Potentially could this technique in the id Tech 6 are used.

This works by ray casting a geometry represented by voxels instead of polygons. The goal is to stream parts of the octree into video memory, thus increasing the complexity of the geometry in such a way that even an unprecedented level of detail arises from close range. The geometric details of which can be shown by this method are almost infinite, which makes it unnecessary to fake 3D details with techniques such as normal mapping.

Although most voxel - test require large amounts of memory (up to several gigabytes), believes Jon Olick of id Software, that it is possible to compress the SVOS at 1:15 bits per voxel at position data.

Virtual texturing

The upcoming id Software games Doom 4 and Rage, equipped with the id Tech 5 engine will use an advanced technique called Virtual Texturing. Textures can as 128000 × 128000 pixels and be larger and can be used not only for terrain, but among other things, for models and sprites.