how to write a step reader?

[dhhjx880713]

I need to develop a tool to compare geometric structure of point cloud from scanned objects with their CAD model. The CAD model is stored in step file. So how could I extract geometric information from step file? I am totally new for CAD. Could you give me some suggestion or tell me any library which can do this job. Any help would be appreciated. Thanks in advance.

[SirSmilesaLot]

which format of STEP is it?? AP204,216,242 or any other and which cad tool are u using?? i guess NX

[z05DSL3A]

The Point Cloud Library (or PCL) may be of help to you...
http://pointclouds.org/

[dhhjx880713]

Thanks for your suggestion. The step file is generated from CATIA. I read a little bit about it, the format of step is P21.

[dhhjx880713]

Hi, I checked, the format of step should be AP203

[SirSmilesaLot]

Then its quite simple, catia has option for import/export of step file, u just need to invoke that option programmatically, and then compare it with existing geometries.
In case u dont want to import the geometry, there are third party API's to parse the step file and extract info, i have worked only AP242 , i dont know much abt others.

u can post ur doubts in solid works forum, people will surely help u :)
https://forum.solidworks.com/thread/12816

[dhhjx880713]

thanks for your quick reply. I know catia can import and export .stp format file. But my task is for a product, to compare point cloud from scanning with its CAD model. I have some background to detect objects from point cloud, but I know nothing about CAD model. I need to write C++ program to compare it, so I need to extract geometrical information from step file generated from CATIA. So I have I could find some libraries which can do this job. Thanks again, I will try to ask in solid works forum.