obj to iges/step

Does anyone know how to convert an obj file into iges/step!? There are a number of websites where you can buy different files. These files are usually high poly count. I've been trying to convert them into iges/step without luck and I'm not sure why -I must say that I'm not an expert in these files -obj, 3ds, etc- I usually work with catia v5-. I don't know if it's because they are made of trias, I don't know if it's about the number of elements...
I've been trying to reduce the number of elements, convert them into quads, then poly to subdv, then subdv to nurbs and finally export as iges. I'm not sure if this is the right procedure. To be honest I always have problems even to reduce the number of elements and haven't succed yet.
I have try also working with "imagine & shape" module. Unfortunately the mesh is huge and it always end up crashing.

Any help would be wonderful. Thanks!

P.S: the last couple of days I've been trying to convert this car:
2018 McLaren 720S

3 Answers

You can convert stl/obj to STEP by Fusion, but file size will be huge due to lots of triangle surface.
Best you can use parametric design software instead of non-parametric design software.