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

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:

Example

Sweep vs. Loft

You can switch between using the Sweep or Loft algorithms when in the "Vessel Contour Modeling" menu:

Sweep	Loft
Uses Contours and vessel path	Uses only contours
Slower	Quicker
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

Example

Looking closer, we can see that the loft algorithm propagates the effects of small contours while the sweep algorithm does not.