High Quality Normal Map Compression

Jacob Munkberg, Tomas Akenine-Möller, Jacob Ström

Abstract: Normal mapping is a widely used technique in real-time graphics, but so far little research has focused on compressing normal maps. Therefore, we present several simple techniques that improve the quality of ATI s 3Dc normal map compression algorithm. We use varying point distributions, rotation, and differential encoding. On average, this improves the peak-signal-to-noise-ratio by 3 dB, which is clearly visible in rendered images. Our algorithm also allows us to better handle slowly varying normals, which often occurs in real-world normal maps. We also describe the decoding process in detail.