Failing Trim Surfaces

Sometimes even when Alias shows (by small green locators) that the COS ( Curve on Surface)in a surface forms a closed loop, it fails to trim the surface. The reasons could be because of either one or many of the following.

  • Presence of very small COS segments, usually to the edge of the surface boundary. Identify the small segment, delete it. Now the open region will be indicated by small yellow locators. Extend the COSs, so that they intersect each other. Please be reminded that the history will be deleted by modifying COS.
  • Multiple COS curves, on on top of another. Delete the offending COS.
  • Presence of COS with history from a previous operation. This is a strange problem. However by deleting the history associated with the COSs, the surfaces can be trimmed.
  • Ambiguous loop regions. Usually caused by the COSs crossing itself. Can be solved by either detaching the COS to multiple COSs or by detaching the basic surface to multiple surfaces.


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