We present an approach to automatically register a large set of color images to a 3D geometric model. The problem arises from the modeling of real-world environments, where surface geometry is acquired using range scanners whereas the color information is separately acquired using untracked and uncalibrated cameras. Our approach constructs a sparse 3D model from the color images using a multiview geometry technique. We project special light patterns onto the scene surfaces to increase the robustness of the multiview geometry reconstruction. The sparse model is then approximately aligned with the detailed model. Planes found in the detailed model are exploited to refine the registration. Finally, the registered color images are mapped to the detailed model using weighted blending, with careful consideration of occlusion and the preservation of image details.