n hour before Richard Haddy's speech, Guennadi Riguer spoke about Compression of maps of normals and introduced a new texture format for using compression of maps of normals. By the way, this seminar was in a certain way connected to the seminar of the effective usage of pixel shaders held by Ashu Rage from NVIDIA the day before. It shows what a great attention IHV pay to usage of maps of normals in modern games.
Maps of normals produce beautiful images but they almost double the texture volume. Maps of normals which do not cause artifacts must be stored in textures of 8 bits per channels at least (RGB8), or better of 16 bits (G16R16), like in all ATI's demos. In order to make the texture volume smaller the company carried out some experiments with DXTn formats (lossy compression called S3TC in OpenGL) and found out that the DXT5 was the most optimal: in this format each of two coordinates (x, y) is stored in its channel: color and alpha. In this format the memory size required is 4 times lower (32 bits against 8 bits)! As the further extension, ATI will support a new format in its new chips. It's based on the DXTC and previously named ATI2N. It differs from DXT5 in compression of only a color component (out of three) using the method identical for the alpha channel compression. The new format will tremendously increase the precision of compressed texture storage compared to the DXT5, with the size being the same.
That was ATI's seminar where the speaker dropped some hints at the future interesting technologies and extension of the current ones without naming definite terms or solutions. When it slipped out that video cards with 512 MB memory onboard will come this year Richard said that there was nothing more to be afraid of as he will get fired anyway