Shape-from-Shading Under Perspective Projection
International Journal of Computer Vision
A Unifying and Rigorous Shape from Shading Method Adapted to Realistic Data and Applications
Journal of Mathematical Imaging and Vision
Shape from shading for the digitization of curved documents
Machine Vision and Applications
Shape from contour for the digitization of curved documents
ACCV'07 Proceedings of the 8th Asian conference on Computer vision - Volume Part II
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A divide-and-conquer strategy in shape from shading problem under fully perspective condition is proposed for the information recovery of book surfaces. The whole recovery process is composed of three sequential steps : preprocessing, apparent shape recovery, and ortho-image generation. Pure shade images are extracted at preprocessing step by introducing phenomenological model of interreflection and by removing pigment parts from observed images. Using existing invariances, equations of slope and that of ortho-image being explicit are derived from equation of shading and that of observation being implicit. Recurrence relation is derived from definition of mean slope in discrete image. Theoretically, it become possible to recover unique shape without iteration using derived equations in case of Lambertian cylinder. However, a feed-back shape recovery process is implemented as practical algorithm in order to overcome self-shadows. Results of simulations and real experiments show the properness and acceptability of the proposed strategy and implemented algorithms.