Adaptive Measurement of Anisotropic Material Appearance

We present a practical adaptive method for acquisition of the anisotropic BRDF. It is based on a sparse adaptive measurement of the complete four-dimensional BRDF space by means of one-dimensional slices which form a sparse four-dimensional structure in the BRDF space and which can be measured by continuous movements of a light source and a sensor. Such a sampling approach is advantageous especially for gonioreflectometer-based measurement devices where the mechanical travel of a light source and a sensor creates a significant time constraint. In order to evaluate our method, we perform adaptive measurements of three materials and we simulate adaptive measurements of ten others. We achieve a four-times lower reconstruction error in comparison with the regular non-adaptive BRDF measurements given the same count of measured samples. Our method is almost twice better than a previous adaptive method, and it requires from twoto five-times less samples to achieve the same results as alternative approaches.