Hello, so, we need first to align both meshes in 3D... then we can compute the difference in volume. I may use a numerical approach. For example, divide the space in voxels... and then, I may count how many voxels are new, and how many voxels are in both meshes... the size of the voxels would give us the quality of the numerical result. I think it can be fast. Please, let me know more about the input format of both meshes. I have master & PhD in graphics computing. I should be a good option for this project. I am a researcher with more than 20 years in this field. Best regards!