tailieunhanh - Active Visual Inference of Surface Shape - Roberto Cipolla Part 6

Tham khảo tài liệu 'active visual inference of surface shape - roberto cipolla part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 66 Chap. 3. Deformation of Apparent Contours - Implementation Figure The epipolar plane. Each view defines a tangent to r so t . For linear camera motion and epipolar parameterisation the rays and r .s o t lie in a plane. Ifr so f can be approximated locally as a circle it can be uniquely determined from measurements in three views. . The epipolar parameterisation 67 or crease discontinuity in surface orientation the three rays should intersect at point in space for a static scene. For an extremal boundary however the contact point slips along a curve r so t and the three rays will not intersect figure and . For linear motions we develop a simple numerical method for estimating depth and surface curvatures from a minimum of three discrete views by determining the osculating circle in each epipolar plane. The error and sensitivity analysis is greatly simplified with this formulation. Of course this introduces a tradeoff between the scale at which curvature is measured truncation error and measurement error. We are no longer computing surface curvature at a point but bounds on surface curvature. However the computation allows the use of longer stereo baselines and is less sensitive to edge localisation. Numerical method for depth and curvature estimation Consider three views taken at times to ti and t 2 from camera positions v to v ti and v 2 respectively figure . Let US select a point on an image contour in the first view say p so to . For linear motion and epipolar parameterisation the corresponding ray directions and the contact point locus r so t lie in a plane - the epipolar plane. Analogous to stereo matching corresponding features are found by searching along epipolar lines in the subsequent views. The three rays are tangents to r so t . They do not in general define a unique curve figure . They may however constrain its curvature. By assuming that the curvature of the curve r 0 t is locally constant it can be approximated as part of