Error during import Of STEP

Hello, I am trying to import some Step files. As long as the files are composed by simple faces everything is all right (Plane, Cylindre)

Using the same Softwares (SolidWORKS AND Catia) when I import Spline Curves or surfaces, Cascade Jamms.

When I started debugging I saw that it stopped at this function :

Standard_Boolean ok = aReader.TransferRoot(n);

Can anyone help me solving this problem please ?

Thanxs in advance.

Best regards. Omar Msaaf

Msaaf Omar's picture

Hello, As I stated in my previous post, I Tried to import some step files and I didn't succeed. What I did yesterday confused me even more. I took a B-Rep Sample from the Cascade Site wich is Misc2.Brep and exported it to a STEP format. Then I tried to import the very file I exported. Without any success.

So could please any one that has a clue help me ? Thanxs best Regards Omar Msaaf

Pavel Durandin's picture

Dear Omar Msaaf,

Some problems which occur in Open CASCADE 3.0 have been already fixed in the next version. The result of translating STEP file into Open CASCADE shape looks better in Open CASCADE 4.0 than in Open CASCADE 3.0.

Please note, that Open CASCADE STEP processor provides only mapping with recomputing of additional information necessary for Open CASCADE boundary representation. In particular case STEP format does not support parameters of vertices on curves and pcurves of edges. So, this information can not be written into STEP file. During translation of STEP file into Open CASCADE shape this information should be recomputed. In some cases ignoring pcurves from STEP file and computing them using projection gives better result.

For that, use read.surfacecurve.mode Interface_Static parameter in the mode 3DUse_Preferred. Please use the following C++ code:

. . .

STEPControlStd_Reader reader;

Interface_Static::SetCVal("read.surfacecurve.mode","3 DUse_Preferred");


. . .

I have obtained better result in Open CASCADE 3.0 using this value of parameter.

Best regards,