A Divide-and-Conquer Strategy in Recovering Shape of Book Surface from Shading

A strategy in solving the shape from shading problem for the shape and albedo recovery of book surfaces under the fully perspective environment is proposed. The whole recovery process is composed of three sequential steps : preprocessing, recovery of apparent shape, and ortho-image generation. A set of pure shade and albedo images are separated in preprocessing step. Implicit equations governing the shading and observation have been transformed into explicit ones. Direct and unique recovery becomes possible by combining the transformed ones and the recurrence relation. A feed-back recovery process using pure shade images is implemented as a practical algorithm in order to overcome selfshadows. Results of simulations and real experiments show the properness and acceptability of the proposed strategy and the implemented algorithms.