tailieunhanh - Active Visual Inference of Surface Shape - Roberto Cipolla Part 12

Tham khảo tài liệu 'active visual inference of surface shape - roberto cipolla part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | . Structure from motion 159 planes via quadrics to superquadrics. All the elements in a coherent set lie on some surface in a family within some tolerance to allow for noise 57 20 101 . No surface model is however general enough not to break down sometimes. Structure from motion Interpreting motion in space by a monocular sensor and reconstructing the depth dimension from images of different viewpoints are fundamental features of the human visual system. This is called the kinetic depth effect 206 or kineopsis 160 . In computer vision the respective paradigm is shape from monocular motion or structure from motion 201 138 . Monocular image sequence analysis to determine motion and structure is based on the assumption of rigid body motion and can be broadly divided into 2 approaches continuous and discrete. The optic flow approach relates image position and optic flow 2D velocity field that arises from the projection of moving objects on to image surface to the underlying 3D structure and motion. These methods either require image velocities of points on the same 3D surface continuous flow fields for example 105 1 or accurate estimation of image velocity and its 1st and 2nd order spatial derivatives local flow fields for example 123 138 210 . Another approach for larger discrete motions extracts tokens from images in a sequence and matches them from image to image to recover the motion and structure of the environment for example 135 159 196 197 219 72 93 214 . Inherent difficulties include The temporal correspondence problem There is an aperture problem in obtaining optical flow locally 201 105 and a correspondence problem in matching tokens in discrete views. The speed scale ambiguity It is impossible to determine 3D structure and motion in absolute terms for a monocular observer viewing unfamiliar objects. Both are only discernible up to a scale factor . the image motion due to a nearby object moving slowly cannot be distinguished from far-away object .