Real-time BTF Rendering

The Bidirectional Texture Function (BTF) is a suitable representation for the appearance of highly detailed surface structures under varying illumination and viewing conditions. Since real-time rendering of the full BTF data via linear interpolation is not feasible on current graphics hardware due to its huge size, suitable approximations are required in order to reduce the amount of data and to exploit the features of current graphics hardware. In this paper we exploit the recently proposed Local Principal Component Analysis (LPCA) compression which provides a reasonable trade-off between visualquality, rendering speed and size of the representation and present a new rendering method which is approximately three times faster than the originally proposed method. This is achieved by reparameterizing and rearranging the BTF-data appropriately so that built-in hardware interpolation between the values of the discrete LPCA representation can be exploited.