Using Digital Bridge Model to Improve Orthophoto Generation

Orthophotos of highway corridor areas are important components of public transportation spatial databases. However, the generation of correct orthophotos in bridge areas is difficult, as without operator assistance distortions are often introduced. To avoid warped bridges in orthophotos, a precise DBM (Digital Bridge Model) should be used along with the DTM (Digital Terrain Model). In addition, aerial images of the same bridge object are required to compensate the occlusion effect to obtain true orthophotos. Fusing LiDAR data and aerial imagery to generate precise digital man-made object model has been widely investigated in the photogrammetric community. However, most methodologies utilize LiDAR elevation information only; the LiDAR intensity information is mostly ignored. In this study, both LiDAR elevation and intensity information are used and fused with aerial imagery to generate a precise DBM, based on which occlusion and distortion effects are compensated and the true orthophotos are produced.