We present a new method for registering multiple 3D scans of a colored object. Each scan is regarded as a color and range image of the object recorded by a pinhole camera. Consider a pair of cameras that see overlapping parts of the objects. For correct camera poses, the actual image of the overlap area in one camera matches the rendition of the overlap area as seen by the other camera. We define a mismatch score summarizing discrepancies in color, range, and silhouette between pairs of images, and we present an algorithm to efficiently minimize this mismatch score over camera poses.