1 Reply Latest reply on Sep 19, 2012 9:37 AM by 1-4EQZK9

    Dealing with importing complicated Biological models (bone, etc) as point cloud

    David Ng

      Hi guys

       

      I am a final year mech student doing his dissertation. I've encountered a problem here I need some help with

       

      To cut a long story short, I have used MIMICS medical imaging software to create a 3D model of a human femur( thigh bone) . I am investigating the mechanical failure of knee implants using FEA analysis (Abaqus.)

       

      so basically, I need to:

      1) create a bone model with CT scan images in MIMICS

      2) export to solidworks, perform some cutting of the bone to fit the implant

      3) laser scan the implant and fit it into the model

      4) fit it all together back in MIMICS, then export it to Abaqus and mesh it.

      5) export it back to mimcis to assign node properties ( I need to do this in mimics because mimics has a handy way of segmenting tissue types that Abaqus doesnt)

      6) export it out to Abaqus to run the FEA analysis.

       

      Right now, I am stuck at part 2.

      I have created a trial bone model (my real CT scans arent out yet) based on older CT scans and have tried to use scanto3D to import it as a point cloud . this works suitably okay for small pieces of bone but it is piss poor for larger, more complicated surfaces. I am losing large amounts of data in the meshing and surfacing of the point cloud. I have no idea how I will turn the surface into a solid even! Would appreciate any help as to how I should go about doing this.

       

      I have also tried other ways of getting the bone model into solidworks, such as DXF, ASCII stl, Binary stl, but they do not work for such a large model. solidworks refuses to build a solid from ascii data as there are too many surfaces.

       

      I understand that polygonal modeling is one of the weaknesses of solidworks and that there are better programs equipped to handle this, such as rhino, but I am obviously limited by what my school is able to provide me.

       

      I have attatched the point cloud and ASCII data for people to have a look, as well as some pictures of what I have been able to experiment so far. do note that the bone model is right now just a rough model and not the final piece.

        • Re: Dealing with importing complicated Biological models (bone, etc) as point cloud

          Hi David,

           

          I have examined your cloud points and mesh and this is not SW fault here - the scan has large occlusions toward the end of the femur and the scan needs to be scan from more orientations because of this. I think this is why you say it is crap, but the old adage applies here "garbage in, garbage out." This is a typical issue with RE The way CT scans occlusions like this can occur because of the regularity increments of how it scans. In more complex areas of the femur, the increment needs to be reduce, or actually use laser scan.  BTW, there are many femur mesh models out there on the web if that is help to you.

           

          Regards

           

          Mark