In this paper we present a method for the acquisition of multispectral Bidirectional Texture Functions (BTFs) for the colorcorrect reproduction of complex materials in virtual scenes with arbitrary illumination. We explain our acquisition setup in detail as well as its careful calibration. The main purpose of the described setup is to provide accurate groundtruth data to verify future methods for simplified multispectral BTF measurements as well as techniques for efficient compression and rendering of multispectral BTF data. We show the accuracy of data obtained with our setup by comparing rendered images to photographs of real scenes. We also verify our datasets using reference measurements obtained with a spectrometer.