Innovative approach to the digital documentation and rendering of the total appearance of fine drawings and its validation on Leonardo's Vitruvian Man

The paper presents a new technique for detecting and rendering the total appearance of a drawing with the aim of digitally visualizing fine drawing collections with perceptive accuracy. A drawing's total appearance can be measured using equipment commonly found in a photographic studio. The system consists of four strobes and an RGB camera. The appearance is defined by its spatially varying spectral reflectance factor, surface macrostructure and surface microstructure. Using stereo-photometric principles, images of each light source taken sequentially from 45° by the normal and annularly at each 90° angle (for four lights) were used to measure the surface normal and diffuse reflectance. An OpenGL viewer was written to render images for specific geometries and for studio lighting. The pipeline from acquisition to visualization was tested on the most famous drawing in existence, Leonardo da Vinci's Vitruvian Man.