Got a scanned file (stl) and with the help of the people at GeoMagic they converted it to a prt file to use in CREO. From the 3cyl I then created a 4Cylinder crankcase using the merge function in assembly. The image shows the finished model.
The process was not as straightforward as one might expect, basically the scanned image is first stitched together to get a cohesive whole called skinning. This creates a stl file. This is imported into GeoMagic Design X and regionalised. This takes some time but creates a 3D image in different colours to delineate discrete areas. The next phase is basically to use the regions to create merged parametric features using familiar tools, Extrude,Revolve etc., but using the regions to set limits. Sketches are created on work planes using cross sections of the scanned model to provide the basis. Surfaces can be created from the scan to be used as such or as cutting or limits for extrusions. Give me a call and I will try to explain further.