HD18009: GSD / EXTRAPOLATE : EXTRACT IS NOT EXTRAPOLATED WHEN PARENT IS JOIN

APAR status

• Closed as Permanent restriction.

Error description

• GSD / EXTRAPOLATE :  EXTRACT IS NOT
  EXTRAPOLATED WHEN PARENT IS JOIN
  .
  This problem is reproducible in R14 latest level.
  .
  When a curve is extracted from a joined surface
  and then extrapolation is done on that error
  occurs - // The wire curvature is too large, so that
  the extrapolated wire cannot reach the target
  plane. Define a smaller extrapolation length. //
  However, extrapolation can be done on the extract
  from the parent surface.
  .
  

Local fix

Problem summary

• GSD / EXTRAPOLATE :  EXTRACT IS NOT EXTRAPOLATED WHEN PARENT IS
  JOIN
  GSD / EXTRAPOLATE :  EXTRACT IS NOT
  EXTRAPOLATED WHEN PARENT IS JOIN
  .
  This problem is reproducible in R14 latest level.
  .
  When a curve is extracted from a joined surface
  and then extrapolation is done on that error
  occurs - // The wire curvature is too large, so that
  the extrapolated wire cannot reach the target
  plane. Define a smaller extrapolation length. //
  However, extrapolation can be done on the extract
  from the parent surface.
  .
  

Problem conclusion

• THIS PROBLEM IS PERMANENT RESTRICTION IN
  CATIA
  .
  Incident Diagnosis
  GSD / EXTRAPOLATE : EXTRACT IS NOT
  EXTRAPOLATED WHEN PARENT IS JOIN
  .
  Restriction Explanation
  Although they appear similar, Extract.1 and
  Extract.2 are modelled in different ways which
  explain the different behaviours.
  .
  1. What happens in the extrapolation of Extract.2
  Extract.2 is the edge of an isolated face (the only
  face of Shell 78181). Its extrapolation is
  straightforward: the only curve underlying the edge
  is extrapolated. This creates no problem.
  .
  2. Why the extrapolation of Extract.1 fails
  Extract.1 is an edge between two shells that were
  joined together. Hence,it merges two curves, which
  represent the edges of the two adjacent faces.
  Therefore, the extrapolation of Extract.1 implies
  the extrapolation of both curves separately. But
  this is possible only if they're still mergeable after
  extrapolation. However, the separately
  extrapolated curves diverge and can't be merged.
  That's why the extrapolation of Extract.1 fails.
  .
  What happens in the extrapolation of Extract.1 can
  be understood by separately extrapolating
  Extract.2 and Extract.3 (where Extract.3 would be
  the corresponding edge from shell 121506). You
  would then find that the extrapolated Extract.2 and
  Extract.3 diverge by as much as 0.013mm at the
  target point of extrapolation, which prevents from
  merging them.
  .
  By-Pass
  One could simply choose to use either Extract.2 or
  Extract.3.
  However, if the goal is to have an edge between
  the two joined faces which can be extrapolated,
  then this edge must be the result of an intersection
  rather than a join. An edge which is the result of an
  intersection between two faces is extrapolated by
  prolonging the intersection between the faces and,
  as a consequence, can maintain the mergeability of
  the underlying curves with virtually no limit on the
  length of extrapolation.
  In order to create such an edge:
  1. Disassemble 121506 and keep only the face to
  which the interesting edge belongs.
  2. Untrim this face.
  3. Untrim shell 78181.
  4. Intersect both untrimmed faces. The result edge
  has a representation on both shells and will be
  extrapolated as an intersection.
  The untrim steps in the procedure above are
  necessary because without them the faces would
  not truly intersect and the Intersect operator would
  have the same effect as the Join operator (i.e.
  edges merged with a tolerance instead of a true
  intersection solution).
  .
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels