Cultural heritage in 3D: Creating models

How can we improve a 3D model obtained by photogrammetry? In this video you will find some indications of how you can edit the models to polish or complement them, and what programs you can use to do it.
Here you will find an example, the 3D model of the Villalbí motorcycle, from the National Museu of Sicence and Technology of Catalonia (mNACTEC).

[balazsschmidt]

Dear Aleix,
have you any documentation About the process? Mainly the technique?