Various implementations disclosed herein include devices, systems, and methods that match image portions of a first set of image portions and image portions of another set of image portions. This may be performed in a such a way that the sum of descriptor distances of the matched image portions is optimized in a globally optimal way. In some implementations, the matching is subject to one or more constraints, e.g., ensuring that each image portion of the first data set is matched with at least one image portion of the second data set and ensuring that each image portion of the second data set is matched with only one image portion of the first data set.