Wish - Multiple unwrapped UV channels

I’m currently playing around with getting geometry into a games engine.

There seems to be two very important fundamentals -

  1. Everything has to be UV un-wrapped properly.
  2. There have to be two UV maps - one for textures and another purely for baking the lighting.

The UV map required for good texturing looks very different from the UV map needed for baked lighting, so I need the facility to be able to unwrap UV’s for texturing onto channel 1 and then unwrap the same object again for channel 2 but with a different arrangement for scale,rotation etc (but keeping channel 1 as is).

The other vital step would be to ensure that both these UV maps can be embedded into an fbx file for file transfer into the games engine.

That would be perfect, thank you!


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Yes, that would be helpful and consequent, as Rhino already supports multiple UV-sets (box, sphere…) per object. I have wished for this before.

Exactly. Hopefully it’d not be a major thing to implement.

I get the feeling that this is the final barrier to getting a successful and quick Rhino-to-Unreal pipeline. So close…

There is already some YT items for that - at least for FBX export. Here a public item: RH-32867.


Thanks for adding this one. The previous YT-entry was about exporting multiple supported UVchannels out (such as three box mapping on an object). In order to do what the OP asked for modifying Exporters isn’t enough though - as Rhino doesn’t let you you create more than on unwrapped UV Set in the first place. Adding that feature was also useful for rendering inside Rhino.

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You can create multiple channels, but it is very hard, and the UI to do so is quite horrible. Editing other UV channels is currently very hard, possibly impossible. That is something @Jussi_Aaltonen probably should have a look at.

Yes, it’s creating the multiple UV channels that I’m after. Also editing them is key. At the moment I can only seem to create one UV channel and this has to be channel 1.

So my current work around is to use box mapping for textures, move these to channel 3. Add surface mapping on channel 1 then do an unwrap which turns it into a UV channel. Then change this to channel 2 when I’m finished and change the box mapping for the textures back to channel 1. It’s a horrible work flow.

But when you’ve got an object that needs a UV map for the textures instead of box mapping etc, then you can’t generate another specific UV unwrap for the light-map which the games engines need.

Oh wait…I think I’ve sussed it out.

Generation and editing of UV maps can only be done on channel 1.

So if you want two UV maps you have to generate your first one then move it to another channel other than 1. Then create a new surface mapping entry as channel 1. Unwrap that to generate your new UV map. You can then assign these to what ever channels you need them to be. If you need to go back and edit one of these maps then you need to move that particular map to channel 1, do your edits, then shuffle the channel numbers back to where you want them.

I need to test out whether these multiple UV maps get exported though, will report back.

So I guess the request should be changed to allowing creation and editing of UV channels to happen on channels other than 1.

They are not. That is the YT issue I linked to.

Ah. Ok, thanks.

Actually do you need to unwrap at all?

Isn’t basic ortho texture mapping sufficient in most cases?
And are you so dissatisfied with Unreal Engine automatic lightmap unwrap, that you need to do it manually?

Box mapping for textures does indeed work for the majority of cases. But there are some circumstances, mainly wood on twisting handrails and intricate furniture that need unwrapping. Not that it’s an issue now, I’ve worked out how to get multiple UV maps, it’s just exporting them that’s the issue.

Unfortunately the auto lightmap unwrap in Unreal doesn’t work for me. I get a whole load of objects with 3 maps instead of two and the original texture maps get rotated in some cases. And you can’t get in to edit the uv’s within Unreal. Unity on the other hand does a good job with auto lightmaps but the graphics in Unity aren’t as good as Unreal.

The solution will be to run my models through another bit of software to do the uv maps. Would just rather it was all kept in Rhino for obvious reasons.

I’ve added YT items for adding mapping channel selection to Unwrap and UVEditor commands.


Thanks Jussi.

Hi, I’m wondering if there has been any traction on this feature? I would love to be able to create multiple UV sets per object in Rhino as well. I am a jewelry designer and am interested in applying different surface treatments, mainly combinations of brushed surfaces with other surfaces being matte or high polish, to the same object. If I try to explode my piece and apply materials to each surface Rhino becomes barely usable. Hoping that this is something that can at least make it into 7.0.

One reason I prefer to use Rhino to create my UVs is that it auto straightens all of my linear curved surfaces which makes it much easier to add a brushed texture. I also don’t have to generate a mesh and attempt to UV that mesh in another app (where I would have to manually straighten the surfaces I want to have a brushed pattern run in alignment with).

I’m experimenting with creating higher res UVs from a custom render mesh (as this is the mesh that the UVs are generated from) and then exporting the model as an obj after meshing it to the same settings. Then in theory I could generate a high enough mesh resolution for the OBJ export and still have my UVs align appropriately to the exported mesh… Then generate additional UV maps in 3D Coat or Blender.

If anyone has any workflow suggestions that would make my life easier, please do share :slight_smile: