I have a 3-D structured grid that I am trying to convert over to an unstructured grid. Here is a picture of the 2-D structured grid with the nodes shown. It is axisymmetric about the x axis (y = 0). I will rotate this to make it 3-D. My main concern in this conversion is that I need to output the volume of every cell from the structured grid. But as you can see, my cells are irregular hexa/penta-hedras, with non-parallel opposing faces (correct me if I'm wrong and I really hope I'm wrong, but I don't think I am). Does anyone have any suggestions on how to compute the volume of each cell?I have some ideas, but am open to other ideas. A colleague of mine mentioned that I could break up the volumes into tetrahedras and compute the volume that way. That is my #1 option so far. My ideas are not so simple and the algorithm can get pretty involved.Does any one have a suggestion on how to compute the volume? 
structured to unstructured grid - calculating volume of cell
mesh generation