Dense 3D reconstruction from two spherical images via optical flow-based equirectangular epipolar rectification

Abstract

In this research, a technique for dense 3D reconstruction from two spherical images clicked at displaced positions near a large structure is formulated. The technique is based on the use of global variational information i.e. the dense optical flow field in a unique rectification based refinement of the epipolar geometry between the two images in a vertically displaced orientation. A non-linear minimization is used to globally align the 2D equirectangular optical flow field (i.e. pixel displacements). The magnitude component of the resultant optical flow field can directly be converted to a dense 3D reconstruction. Thus, the epipolar geometry as well as the 3D structure can be estimated in a single minimization. This method could be useful in measurement and reconstruction of large structures such as bridges, etc. using a robot equipped with a spherical camera, thus helping in their inspection and maintenance.