Trimmed B-Spline surface with 1800 edges...

Dear OCC community,

I'm currently try to import IGES file and found 1800 edges on one of the trimmed B-spline surfaces. Trimming line look's nice and smooth, but consist of huge number of small pieces. Is it any easy way to replace this edges by the several splines? Thank's in advance.

Roman Lygin's picture

Hi Alexander,

Until your original file contains that many edges, the most likely cause of this is split of C0-curves into C1 which is by default turned on by the OCC IGES importer (and is only done in IGES).

Please refer to the Data Exchanger documentation on how to disable that - see read.iges.bspline.continuity.

Hope this helps,

Alexander Alexanov's picture

Thank you Roman,

Interface_Static::SetIVal ("read.iges.bspline.continuity",0);

It's comes like one polyline.
This is something I can manage. I hope.


Timo Roth's picture

In the documentation it says:
"(Open CASCADE Technology requires that the curves in a model be at least C1 continuous; no such
requirement is made by IGES)."

What does it mean that OCCT has this requirement?
Does it mean that you can hardly work with such curves in OCCT and therefore the conversion is made by default?

Also, the following sentence from the documentation of this parameter is not quite understandable:
"This parameter does not change the continuity of curves that are used in the construction of IGES BRep entities. In this case, the parameter does not influence the continuity of the resulting OCCT curves (it is ignored)."
Can someone explain It?