Shape from Fluorescence

Beyond day glow highlighters and psychedelic black light posters, it has been estimated that fluorescence is a property exhibited by 20% of objects. When a fluorescent material is illuminated with a short wavelength light, it re-emits light at a longer wavelength isotropically in a similar manner as a Lambertian surface reflects light. This hitherto neglected property opens the doors to using fluorescence to reconstruct 3D shape with some of the same techniques as for Lambertian surfaces – even when the surface's reflectance is highly non-Lambertian. Thus, performing reconstruction using fluorescence has advantages over purely Lambertian surfaces. Single image shape-from-shading and calibrated Lambertian photometric stereo can be applied to fluorescence images to reveal 3D shape. When performing uncalibrated photometric stereo, both fluorescence and reflectance can be used to recover Euclidean shape and resolve the generalized bas relief ambiguity. Finally for objects that fluoresce in wavelengths distinct from their reflectance (such as plants and vegetables), reconstructions do not suffer from problems due to inter-reflections. We validate these claims through experiments.