In order to recover the shape of surfaces that have specular reflection
a new shape from shading method is presented based on the Ward reflectance model and the perspective projection. It is assumed that the light source is located at the camera's optical center and that the attenuation of the illumination due to distance is taken into account. The bidirectional reflectance distribution function of the specular surface based on Ward model is designed
and then a partial differential equation(PDE)of the shape under perspective projection is established. The PDE is solved by the Lax-Friedrichs sweeping method and the modified nonlinear artificial viscosity for the surface shape. The proposed method is more accurate and stable than other existing methods of the same kind. Experiments on synthetic specular vase show that the reduction in the average height error of the proposed method is about 13.5% compared with the method under orthographic projection.
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references
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