New methods and tools for 3D-modeling using range and intensity images

New methods and tools for 3D-modeling using range and intensity images Alejandro J. Troccoli Systems for the creation of photorealistic models using range scans and digital photographs are becoming increasingly popular in a wide range of fields, from reverse engineering to cultural heritage preservation. These systems typically employ a range finder to acquire the geometry information and a digital camera to measure color detail. But bringing together a set of range scans and color images to produce an accurate and usable model is still an area of research with many unsolved problems. In this dissertation we present new tools and methods for creating digital models from range and color images, with emphasis in large-scale outdoor scenes. First, we address the problem of range and color image registration. In this area, we introduce a semi-automatic tool for range and color image registration that makes use of line-features to solve for the position and orientation of the digital camera. This allows us to efficiently register images of urban scenery. Secondly, we present a registration technique that uses the shadows cast by the sun as cues find the correct camera pose, which we have successfully applied in the creation of a digital model of an archaeological excavation in Monte Polizzo, Sicily. We also address the problem of how to build seamless integrated texture maps from images that were taken under different illumination conditions. To achieve this we present two different solutions. The first one is to align all the images to the same illumination. For this, we present a technique that computes a relighting operator over the area of overlap of a pair of images, which we then use to relight the entire image. Our proposed method can handle images with shadows and can effectively remove the shadows from the image, if required. The second technique we developed for the creation of integrated seamless texture maps uses the ratio of two images to factor out the diffuse reflectance of an image from its illumination. We achieve this without any light measuring device. When computing the actual reflectance we remove from the images any effects of the illumination. This allows us to create new renderings of the scene under novel illumination conditions.