ok, got it. yes indeed poor photography in photogrammetry leads to holes and weird artifacts in mesh, and it makes life harder in the sens that you are dealing with millions of triangles so you cannot manually clean it up and need to rely on auto clean up tools, that sometimes work but not always. and iam not well informed on how / why things dont always work out nice in ladir 3d scanners. At least reality capture in photogrammetry side of things does a descent job in decimation and has topology correction tools. it still gives you triangles, but no non manifold geometry. I guess in many cases people who scan / sell things are not necessarily good 3d modelers, and its just extra step / time to clean up geometry, so not everyone does it.