I’m having a problem with the way OpenCascade translates my model’s parameters into units when I save the model as an IGES file.
Here’s what I’m doing:
I’m creating an aerofoil from (x,y) vertices and then converting with PointsToBspline. This edge is converted to a wire and then added to my shape. I output the model as an IGES file. The airfoil’s parameters range from x=0 to x=0.5 (My intent is that this represents a chord length of 0.5 metres).
The problem occurs when I specify the model’s units.
If I use:
IGESControl_Writer ICW ("M", 1);
Then my chord seems to be converted to MM when I re-load the IGES into CFD Meshing software (ie 0.0005 Metres).
If I use:
IGESControl_Writer ICW ("MM", 1);
Then when I load into the mesher, I see the chord as 500mm (or 0.5 Metres).
Does anyone know why this is happening?
P.S. I’ve checked the IGES files in Notepad and I do see 2HMM when I specify “MM”. When I specify “M”, I do see 1HM. So I’m even more confused!
Is there some inherant unit used for point or vertex data that I don’t know about? Or is something else happening?
Thanks, in advance, for any help you can give me,