期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2007
卷号：XXXVI-5/W47
出版社：Copernicus Publications
摘要：Texture-mapping in close-range photogrammetry focuses mostly on the generation of large-scale projections of 3D surfaces, the most common instance being that of orthoimaging. Today, photogrammetry increasingly uses terrestrial laser scanning as basis for genera- tion of 3D models. For a full exploitation of fully 3D data, however, typical shortcomings of conventional orthorectification software (inability to handle both surface self-occlusions and image occlusions; single-image texturing) must be addressed. Here, the authors elaborate on their approach for the automated generation of orthoimages and perspective views, based on fully 3D models from laser scanning and multi-image texture interpolation. The problem of occlusion is solved by first identifying all surface points visible in the direction of projection; texture is then interpolated through blending using all images which actually view each particular surface point. Texture outliers from individual images are automatically filtered out with a statistical test. Yet, further means for excluding outlying colour values are needed. Rather than using the depth maps of source images to identify possible occlusion borders, these borders are automatically extracted directly on the orthoprojection of each image. Their back-projection on the corresponding image, suitably processed with a morphological operator (dilation), defines 'risk buffers' on each image and suppresses their participation in colour interpolation. Combined with a statistical test, this procedure has proved beneficial for the quality of the results. Practical tests based on image sets with considerable variations in image scale have indicated that such new features of the algorithm facilitate the cooperation of laser scanning with photogrammetry for the automatic multi-view synthesis of textured projections
