Loss of file hierarchy when exporting to STEP

[shinji-pons]

Hello!

I'm using Alias Surface 2025.1 and I cannot seem to get anything but a completely flattened file when exporting to STEP.

According to the documentation, I should be able to preseve at least the layers and grouping structure. It says nothing about folders though...

I created a wire file with some surfaces put inside of groups and layers and gave them some recognizable names - but when I import the step file into Shapr3D, it all gets lost.

I've tried all the application protocols provided and all failed to get Alias file hierarchy over to Shapr3D. I tried using "Save As" (to Step) and "Save Active As" (to Step) but no luck at all.

I'm wondering if I'm doing something wrong or if somehow the step translator is not working correctly?

This other page in the documentation shows the export settings for STEP, which show the checkboxes for layers and groups:

https://help.autodesk.com/view/ALIAS/2025/ENU/?guid=GUID-1B42A2EC-DA3C-4030-AEBB-05C77980E8B7

The only thing missing in Alias Surface is the Model Type option, but I don't think that is the problem?

Any help would be greatly appreciated.

[rauscht]

Hey Shinji,

hope this post finds you well!

To the problem you are facing:
I have done some tests on that:

• Created a wire file containing Folders, Layers and Groups
  => groupsAndLayers.wire
• Exported it as STEP file with options "Want Grouping" and "Want Layers" toggled on
  => groupsAndLayers_2026.0.wire.stp
• Brought that STEP file back into Alias and saved the result as wire file
  => groupsAndLayers_2026.0.wire.stp.wire
• Created a screen shot of the result
  => groupsAndLayers_2026.0.wire.stp.wire.png

(I have done that using my local Alias AutoStudio 2026.0 beta which will become available soon. But the result is identical if I use Alias Surface 2025.1.)

As you can see, Groups and Layers are contained in the STEP file (as otherwise they would not show after re-importing the STEP file into Alias) with a few limitations:

• Layer Folders are not supported
  The reason is likely that STEP does not support hierarchical layers, but I would need to confirm on that (i.e. by reading ISO_10303-21).
• Groups will always show up in the "DefaultLayer"
  The reason here is that Layers and Groups are two concepts of grouping things which in the general case might contradict each other, like e.g. by putting group "cube" into "Layer1" but some of its faces a different "Layer2". Alias is solving that by placing group "cube" (and all of its sub groups) into "DefaultLayer"

Could it be that the import mechanism of Shapr3D is the problem in your workflow?

Hth

Thomas

[rauscht]

And here are the files I was referring to.

[shinji-pons]

Hey Thomas!

So Shapr3D uses HOOPS Exchange to read the STEP files and it seems that Alias might not be writing the STEP files in a way that is supported by HOOPS.

I can send STEP files with both Shapr3D and Plasticity to each other and the group structures transfers over without a problem.

But from STEP file from Alias loses all but the surface names when imported inside of Shapr3D, Plasticity and the HOOPS Exchange Desktop viewer. Below is a screenshot of the HOOPS Viewer when I imported the STEP file you uploaded. As you can see, only the surface names survived.

I don't know which ISO standard HOOPS follows, but according to their documentation, HOOPS support AP242:

https://docs.techsoft3d.com/exchange/latest/start/format/step_reader.html

Digging into the STEP files themselves

Shapr3D and Plasticity write the folders in the following way:

#35=SHAPE REPRESENTATION ('Cube and Cylinder and Torus', (#15,#490), #33);

Whereas Alias writes the node groups like this:

#25=GROUP('frontAndBack',$);

I'm not an expert on this issue so I will defer to you whether this is right or not. I'm more than happy to try more suggestions if you have them.