La Coupole: an SVBRDF measurement device for large and non-planar objects

We present La Coupole , a device for measuring SVBRDF of large, non-planar objects, which aims at reproducing the appearance of an object as it would be seen under any lighting conditions and as perceived by the human eye at a minimal distance of approximately 30 cm. The ultimate goal is to provide virtual tools for the visualization, inspection, and diagnosis of ancient and fragile objects. With this in mind, we compare three BRDF representations for reconstructing any measured BRDF: two of them — spherical harmonics and radial basis functions — do not make any prior assumptions about the data, whereas the third one, a GGX microfacet-based model, is a parametric representation. The paper also provides details of the geometric and radiometric calibration process, along with an in-depth study of their respective uncertainties.