Save as V5 from V7 excludes SubDs without warning

Hi All,
Yesterday working tired at night I saved a model from V7 to V5. The model was almost ready, containing SubD parts with some other NURBS geometry. I did it just to do some minor NURBS editing.
After some time working and saving, I realized that the SubD model was not just hidden, it wasn’t in the file anymore…

SO, don’t you think that the export and save as window should warn the users what would happen? or offer to save the control polygon or baked (to NURBS version of their subd).

Something strange is that if you open the V5 version in V7, the subD is there, but as shading mesh.

Any idea?

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Since the V5 file format does not support SubD objects, what would you suggest?

This is not a new issue.
Anytime you save a file to a previous version, you run the risk of losing data because it just did not exist in the earlier Rhino version.

No, you are right John, it crops up in all sorts of software. Often though, when saving to an earlier version, you get a warning dialog so you get a chance to back out. I was surprised to find that Rhino doesn’t do this. It wouldn’t be difficult to add it to Rhino and would be a nice touch - could this go onto the list of requested enhancements?



The warning is still there but only if you are updating an existing file with a previous version.
I just tested it using SaveAs

Thanks John, that’s good. Can we request something similar for new files?

It’s true @John_Brock , thanks, I didn’t see the warning.

This is what help says about saving to V5:
“SubD objects are saved as ordinary mesh objects” which is not valid at the moment.
It would be nice to have an option to export subs as control polygon mesh or NURBS if possible.

Hi @laborda, saving as low poly meshes (_extract control polygon) would be the least damaging option, since a Nurbs conversion is not reversible. The only thing you would lose with SubD cages as meshes is creasing information. Thoughts?


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If you read the help about exporting from V7 to V5, it says that the subD objects would export as ordinary mesh objects. But if you open the exported object in V5 you get nothing, if you open the same file in V7 what you get is just what seems to be the shading mesh.

If I have to choose how subD objects should export to older version, I would ask for a default option of control poly mesh, like @gustojunk said it’s the best option in most cases.

I’ve recategorized this message thread to the SubD list.

At the moment there is no automagic solution. You kind of have to know what is happening behind the scenes to get useful info.

in order to have useful info in v5, you need to exract the control cage, save it as a rhino file or obj and then open it in v5 and convert it to subd again with something like tsplines.

as explained before, v5 has no idea what v7 subd is and as such there will be a data loss unless you plan ahead. Even if the part comes into v5 as a meshed object, that is not useful if the intent is to work on the subd in any meaningful way as the mesh will be quad dominant, but also triangulated.

can you elaborate a bit on how you are using or want to use the v7 subd data in v5?

Also, on a personal note:
hi! I miss working with you! Hope all is going well for you and your family.

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Hi Kyle,

I thi we are talking about the concept of UX Affordances here. What’s the right things to do for users that are about to lose a bunch of work because they saved what they created in Rhino as a file version that does not support their creation?

For those not familiar with the concept: An affordance is what a user can do with an object based on the user’s capabilities . As such, an affordance is not a “property” of an object (like a physical object or a User Interface)

What are Affordances? | Interaction Design Foundation (IxDF)).

I hope this helps,


You may probably know I understand how to move from one version to the other using other formats or taking care of some details. But what I’m asking here is to copy a bit of the philosophy Nikon and Adobe have, or had at least for some years.
They allow you to share their product, no matter what version you are sharing. If your camera is old you can use a lens with autofocus but in manual mode. The same happens with PSD, you don’t need to save a PSD in an older version or anything special, you just save it in PSD, and photoshop will give you the most it can. You may lose nondestructive effects or something but nothing crucial.

In my particular case, I still use V5 for VSR… I’m not using T-Splines too much. Most SubD I do is done inside V7/V8 or in another poly modeling program.

Kyle! I also miss working with you! We are all good, still in Argentina but open to new adventures.
I hope you and yours are going great too.


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