We more or less have the same problem. For our study we need a surface-mesh from a segmentation that was already done in Mimics.
Strangely enough Mimics doesn’t give you the possibility to make a real surface-mesh (it always does some sort of smoothing), so I exported the segmentation as a dicomserie and then imported the dicoms into Slicer.
Then I segmented the included Mimics-mask by choosing the proper theshold values. After that I saved the segmentation as an STL without smoothing.
But now, when I import the Slicer-stl back into Mimics, the resulting mask (in red) is offset by about halve the voxelheight in the Z-direction (see screenshot).
For our study it’s very important that the STL is exactly in the same coördinate system as the dicom!
We discussed this problem and the only thing we came up with for now is that it might be caused by where the application (Mimics, Slicer, …) defines the position of the Z-coördinate; at the top, in the middle or at the bottom of the voxel.
I don’t believe that that will be the case, because I think there are fixed rules for this in the dicom parameters. But we haved got a clue.
Who gave help us in this?