Advanced Geometric Modeling¶
Importing and exporting existing CAD models¶
CAD modeling provides an infinitely-smooth description of the geometry. The ability to import CAD allows for the inclusion of devices of complex shapes. The following formats can be imported into CRIMSON: - IGES/IGS - BREP - STEP/STP The meshing and solver setup are the same for an imported model as for models created in CRIMSON. You do not need to have a DICOM image loaded to imported a solid geometry. Click on the "Import" button in the main toolbar to import a CAD geometry.
To export a model, right click on the blended geometry and select "Export..." from the context menu.
Boolean operations allow for solids to be blended or removed. This allows for easy modification of subject-specific models in the context of 'virtual surgical planning'. The basic boolean operations are:
Sweep vs. Loft¶
You can switch between using the Sweep or Loft algorithms when in the "Vessel Contour Modeling" menu:
|Uses Contours and vessel path
|Uses only contours
|More complex output
- Slower and less robust blending and meshing
|Less complex output
- Faster and more robust blending and meshing
|Use only for special cases
- Very tortuous vessel
- Vessels that simultaneously change direction and cross-section
|User whenever possible
Looking closer, we can see that the loft algorithm propagates the effects of small contours while the sweep algorithm does not.