SREVAS: Shading Based Surface Refinement under Varying Albedo and Specularity

Shape-from-shading and stereo vision are two complementary methods to reconstruct 3D surface from images. Stereo vision can reconstruct the overall shape well but is vulnerable in texture-less and non-Lambertian areas where shape-from-shading can recover fine details. This paper presents a novel, generic shading based method to refine the surface generated by multi-view stereo. Different from most of the shading based surface refinement methods, the new development does not assume the ideal Lambertian reflectance, known illumination, or uniform surface albedo. Instead, specular reflectance is taken into account while the illumination can be arbitrary and the albedo can be non-uniform. Surface refinement is achieved by solving an objective function where the imaging process is modeled with spherical harmonics illumination and specular reflectance. Our experiments are carried out using images of indoor scenes with obvious specular reflection and of outdoor scenes with a mixture of Lambertian and specular reflections. Comparing to surfaces created by current multi-view stereo and shape-from-shading methods, the developed method can recover more fine details with lower omission rates (6.11% vs. 24.25%) in the scenes evaluated. The benefit is more apparent when the images are taken with low-cost, off-the-shelf cameras. It is therefore recommended that a general shading model consisting of varying albedo and specularity shall be used in routine surface reconstruction practice.

Science intensive technology with ultrasound use at hard-to-reach surface refinement in complex parts

A technical problem in assurance of life in parts of fuel equipment and a system of natural gas transportation is analyzed taking into account their pollution in the course of manufacturing and operation. An outlook in decontamination by a method of ultrasonic refinement is shown. There is offered and proved experimentally a method for ultrasonic refinement efficiency increase up to 10 times for the surfaces mentioned above by means of imparting ultrasonic oscillations to a product directly in the area of pollution detec-tions.