Under the sample/ subdirectory, you can find an example script to demonstrate how to use metch toolbox to register a point cloud to a triangular surface mesh. There are extensive comments in the scripts and you should be able to understand the workflow by reading the full script.
The first example, demo_registration_ex1, is a demonstration of calling separate metch subroutines to perform a registration task. The surface mesh was extracted and resampled from a head MRI scan using iso2mesh toolbox. The point cloud is obtained with a polhemus tracking system from a MEG scan at Martinos Center. The point cloud contains a few standard landmarks of the head, also known as the 10-20 points for EEG/MEG experiments, and a contour scan of the head surface. The task is to register this point cloud based on the surface mesh of the head, and move the points right onto the surface at the registered position to set up the geometries for the subsequent modeling.
The first step of the registration is to create a rough initial mapping. The point cloud and the head MRI surface can be defined in different coordinate systems, as well as units and orientations. This step is to create a good initial mapping by selecting a number of point pairs (the landmarks, or 10-20 points) from both the point cloud and the