Fig. 7

Examples of three comparisons between rendered images of the shape model with spacecraft images to assess model quality. a Illustration of the keypoint matching method using SRC image H3245_0006sr2 of Phobos. Matched keypoints on the reference image (left) and the rendered model (right) are connected by lines. b Illustration of the keypoint distance method using Viking Orbiter image f428b22 of Deimos. The collection of distances between all keypoints is shown on the reference image (left) and the rendered model (right). c Illustration of the limb/terminator method using Viking Orbiter image f123b03 of Phobos. Limb and terminator positions are outlined in green on the reference image (left) and on the rendered model (center). A difference image (right) shows mismatches in black or grey