topic Re: Exporting Meshes, UV Scale/Density Wrong in Fusion Design, Validate & Document Forum

Exporting Meshes, UV Scale/Density Wrong

awilliamwright — Sun, 21 Aug 2022 19:27:28 GMT

This is probably an unusual situation, but I've been experimenting lately with building elements in Fusion to be used for pre-visualization in Unreal 4. I've had a lot of strange problems as I've undergone this, but I recently realized that the biggest problem is probably due to Fusion incorrectly scaling the UV maps when exporting a project as a mesh.

LONG RAMBLE:

Unreal wants all units to be in centimeters, so if you export a project into FBX from Fusion with the default units as centimeters, they will import into Unreal at the perfect scale. However, the UV maps are exactly 100x too small. Or 100x too dense, meaning lighting never works (this was the first problem I ran into, because I was only using flat colors to texture items for a long time.

Now, correct texture density is not important for previsualization, but having basic lighting work is important. But it was experimenting with better materials/textures that revealed the problem.

I can FAKE the right scale on the textures by going into the scripting for the materials and forcing a "scale" parameter. However, this is extremely tedious and I have to do it for every single material I'm using. Also, I'm suspicious it won't fix the lighting issue at all (since lighting fidelity is dependent on healthy UV maps, not texture density).

QUESTION:

How do I fix this?

I tried exporting the project from Fusion with the units as meters, then scaling up by 100 when importing in Unreal, but this did nothing. The UV density is the same, regardless. Fusion apparently doesn't care how large something is, it just decides to have UV density be 100x what it should be.

I really, really don't want to bring it into Blender and engage in mortal combat with its UV tools (Lord help me, I will lose my will to live).

Re: Exporting Meshes, UV Scale/Density Wrong

TrippyLighting — Mon, 22 Aug 2022 11:08:11 GMT

I don't think you'll get a lot of feedback on this topic here on the forum. But I do think this deserves attention as real-time 3D technolgies are basically at everyones fingertips.

@jeff_strater @jodom4 could you direct this to the correct team and perhaps solicit some feedback?

Re: Exporting Meshes, UV Scale/Density Wrong

awilliamwright — Mon, 22 Aug 2022 14:32:51 GMT

Yeah, after I thought about this post I started to worry that would be the case

Re: Exporting Meshes, UV Scale/Density Wrong

jodom4 — Mon, 22 Aug 2022 21:45:03 GMT

@harv.saund, care to weigh in?

Re: Exporting Meshes, UV Scale/Density Wrong

harv.saund — Tue, 23 Aug 2022 12:41:17 GMT

Hey @awilliamwright

I would love to learn more about your workflow, as @TrippyLighting says this technology is becoming more accessible and we do need to do a better job with UV scale / density.

I will reach out over DM and setup some time to talk.

Thanks,

Re: Exporting Meshes, UV Scale/Density Wrong

TrippyLighting — Tue, 23 Aug 2022 13:19:38 GMT

@harv.saund while you're at it, the UV mapping issue isn't the only problem.

FBX export has two other issues:

1. It is an online converter and not the fastest.

2. This is the more important issue of the two. Users have no control over the resolution of the exported mesh!

Re: Exporting Meshes, UV Scale/Density Wrong

awilliamwright — Tue, 23 Aug 2022 17:18:53 GMT

Email sent!

Re: Exporting Meshes, UV Scale/Density Wrong

allanJKZ4E — Wed, 01 Nov 2023 12:18:40 GMT

Did you ever find a fix for this? I've been using Fusion with TwinMotion and I have to use .skp exports instead of .fbx because of the 100x scale issue (also, .fbx are for some reason using the wrong axis as UP direction by default when imported to TwinMotion -- SketchUp files work fine).