Please, help me with OCCS geometry

Hello! I am Anna and I am a student of Novosibirsk State University. I'm coding a project on C++ with MFC and I can't understand next thing: 
1) I load STEP project (It is a room) with the help of  MFC sample
2)Then I want to add a box into this STEP project.  I've already found  how I can add size and point of box.
3) But How can I convert my real box size to internal geometry? Where is the scale?
I want to read the real Box size and real Box coordinates from the Edit control, convert them with the scale of all STEP project. So I need to know where  STEP scale in OCCS classes stores and how it is used to convert into OCCS geometry. Please, help me!

qa qa's picture

Hello Anna,

OCCT internally converts model into millimeters by default. If your step file has other units or you want use other scale you need to set static variable. Here is the example:

Interface_Static::SetIVal("xstep.cascade.unit", value);

Also, documentation contains some information:

Programmatically, you can get size of your model using  BRepBndLib class.


a.kliuchnikova_144191's picture

Thanks a lot! I'll try it and ask if I get some new questions!

mnvinothprasath_143247's picture


I am using following command 

"Interface_Static::SetIVal("xstep.cascade.unit", value);"

but values of step files element don't changed.

 is there any way to change default unit system to write step file ..?


qa qa's picture

Hi, for step file you can use "write.step.unit" variable.


mnvinothprasath_143247's picture

yes we have used that command 

Interface_Static::SetCVal("write.step.unit", "FT"

but actual value of element wont changed.

for example if we have element with height of 10 feet , then we need default unit system as Foot or "MM with conversion(304.8 * 10 = 3048."