This is the step where the orig surface (ie, surf/?h.orig.nofix) is created. The surface is created by covering the filled hemisphere with triangles. Runs mri_pretess to create a connected WM volume (neighboring voxels must have faces in common) and then mri_tessellate to create the surface. The places where the points of the triangles meet are called vertices. Creates the file surf/?h.orig.nofix Note: the topology fixer will create the surface ?h.orig. Finally mris_extract_main_component will remove small surface components, not connected to the main body.