UDC 528.852.3
THREE-CYCLE SURFACE EDGES ANALYSIS ALGORITHM FOR OCCLUSIONS DETECTION DURING ORTHORECTIFICATION
O. A. Presnyakov, Ph.D. (Tech.), Leading Researcher, RSREU, Ryazan, Russia;
orcid.org/0009-0007-3962-0724, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
The aim of the work is to create an algorithm for occlusion detection during orthorectification of satel lite images using backward projection. Occlusions are the areas of an orthoimage that are obscured by tow ering objects. Processing using indirect method leads to incorrect filling of occlusion areas by repeated fragments of an image. According to the developed algorithm, a pixel belongs to obscured if a viewing vector above it intersects with piecewise-linear surface that interpolates digital surface model (DSM). The algo rithm includes three cycles of iterating over the edges of this surface. The first cycle processes edges, which projections in DSM coordinate system are located vertically, the second – horizontally, and the third – diag onally. The algorithm provides reliable detection of occlusions without omissions and false identifications.
Key words: : occlusion, orthorectification, backward projection, DSM, intersection of ray and surface, ray tracing, iteration over surface edges, piecewise-linear DSM interpolation, true orthophoto.