Step export creates false surface direction if "Export parameter space curves" is checked

Dear all, AP214AutomotiveDesig_ExportParameterCurves_off.stp (54.7 KB) AP214AutomotiveDesig_ExportParameterCurves_on.stp (115.8 KB) Testobject.3dm (131.3 KB)

I have been exporting data from Rhino to step with the AP214Automotive scheme and “Export parameter space curves” option checked. When we imported the file into “HiCAD” i have noticed that for some objects the representation of shaded surfaces is wrong. There seems to be an issue with the direction of the surfaces. The problem doesn’t appear any more if the “Export parameter space curves” option is uncheck. I don’t know what this option is supposed to do yet, but this behavior seems to be strange. Its also strange that when i export multiple instances of the same block object, some objects in the step file have this issue and some objects don’t have. I am using Rhino 7 SR5 2021-4-10 (Rhino 7, 7.5.21100.03001.

Best Peter

Hi Peter - are any of these blocks mirrored from the original orientation? And does the problem occur if the objects are not blocks in Rhino?

If you do not especially need these parameter space curves in the target application, then there is nothing harmed by simply unchecking the box.


Hello Pascal,

i am not 100% sure if the block with the display issue is mirrored but i think this is the case. I have uploaded a file with one block that is exported correctly and the other one having the bug. Indeed, if I explode the blocks, the surfaces are displayed just fine;
Objects_with_issue_and_without.3dm (558.0 KB)