Step Export with colored face

Hi everyone,

one of our clients has demanded a STEP file with one colored face (reprecenting the “viewable” side of the steel part).

They have sent an example file, which, when importet to Rhino doesn’t show the coloring. However, when imported to Inventor, the color is visible.

So here’s the question:

Is it possible to create a STEP file with a colored face of a polysurface in Rhino? And if so, how could this be done?

Attached please find the original step file: example.stp (129.5 KB)


This is an option that has been added to the Rhino WIP when importing a Step file. You’ll need to uncheck Join surfaces for the color to be maintained. In v5 unchecking Join on import will provide separate edge color but not shading. In both cases the model comes in as a block.

I see you’re part of the WIP Serengeti group already Martin, give it a try there to see what I mean and let us know if that works for you.

Hi @BrianJ

thank you. The import works great that way in Rhino WIP.
The question for me would be how to CREATE such a file. So another party can see my highlighted faces and still keep the idea of being a Solid.

(Maybe the exporter could try to join groups of faces, during export or so.

I tired to directly export what I imported, but this turns my “solid” into “surface collection”.


I’m thinking the importer in the program you’re going to will need a similar option as that of the Rhino WIP now. I’d assign materials to any separate selections and then create a Block before exporting as Step. Unfortunately this doesn’t work now even if it should but changing a display color for an object does seem to export with the Step. I’m testing this by importing the Step back into the WIP though and switching the display mode to use objects color versus layer. The application you’re going to will likely be a factor here too.

@chuck should the Step export in the WIP maintain color assignments from materials or display color? In the attached file I’ve set the display color to by parent which I would think uses the material assignment within the block if that can be saved in a Step. StepColors.3dm (151.7 KB)

Step only uses display color. I’ve avoided materials since they can be more complex than just a color and they are only visible in a rendered view. I guess it might be reasonable to have an export option to assign color to a surface based on its material’s ambient color or something like that. One problem is that if you then import the result back into Rhino you would have to chose to not join the surfaces in order to see the colors.

I guess, in General, display color would be better. But - currently it cannot be assigned to a face of a polysrf. Maybe, that would be something that can be changed… Not sure if it makes sense only for the STEP import/export to make such a large change… but maybe there are other scenario, where that would make sense.

Alternatively. Maybe, “Use Material Coloring” could be an export option.

P.S.: … The target Application is Autodesk Inventor

That would be a useful feature for regular modelling too.
… Same for layers …