Alignment of 3D point clouds to overhead images

We address the problem of automatically aligning structure-from-motion reconstructions to overhead images, such as satellite images, maps and floor plans, generated from an orthographic camera. We compute the optimal alignment using an objective function that matches 3D points to image edges and imposes free space constraints based on the visibility of points in each camera. We demonstrate the accuracy of our alignment algorithm on several outdoor and indoor scenes using both satellite and floor plan images. We also present an application of our technique, which uses a labeled overhead image to automatically tag the input photo collection with textual information.