3ds max uvs corrupt?

Ahrkey

Hi, I got a couple of models I made in max that keeps losing uv coords when I export them to FBX. They look fine in the max viewport and in uvwunwrap. But as soon as I export them to FBX they vanish.

I found a way to fix this through making a new box, delete the geo and attach the old geo... this also removes the uv's and I have to load em again and now it works for exporting. But I have todo this everytime I export and since my models consists of several objects(Sometimes up to ~25) this becomes very tedious if I wanna make changes(which happens quite alot during development).

Anyone seen or dealt with this before? This just applies to some models not all of them.

Mark Dygert

Are you collapsing your stack before exporting? FBX doesn't handle the modifier or history stack well at all. What about exporting to something simple like obj do they disappear then also?

Does the channel actually disappear or do you have your UV's loaded onto another channel besides the default?

If you re-import the model and check the channel info (Tools > Channel Info) is "1:map" there? If you have more such as 2:map and so on you have multiple UV channels. You can use the clear button to remove them.

EarthQuake

Make sure your uvs are on channel one, and that you dont have like 3 other uv channels or something, as its likely trying to export the wrong channel

renderhjs

never happened to me,- though my suggestion would be:

select the objects you want to export, then shift+drag copy them and then finally export that copy. Delete the copy objects from your scene and continue with whatever.

At least I write my exporters in a way that they create a temporary snapshot mesh of the model I want to export so that I have the final state I see minus the Pivot position. I assume that many other exporters work the same way because doing so you don't touch the original object to be exported.
So maybe its different with your FBX exporter,- not sure. You could do a test and see if exporting the objects really affects your scene objects by reading out a file size hash value of your max file (save before exporting and read the hash value, and save after exporting and read the hash value).
Should those values differ you have prove that in some way the scene was altered.

Possible solution ideas:
Write a wrapper script that exports the selected models using still the max internal export methods but making a temporary copy of each object in your selection before exporting and deleting them afterwards.

Ahrkey

proved to be several uv-channels allthough max somehow made them without my consent. The engine simply imported uv's without questioning which channel to use.

Thanks alot!

ColMatrix

Note! solution was found, see end of post.

Hi All,

found this thread being closest to my issue, but unfortunately no soution to the problem. I hope there are no issues with adding to the post. The Problem I have is exactly the same as Ahrkey, except the Maps Channels were created on purpose. I have many models within this project - all the same and this is the first with issues.

UV Map Channel Layout

Channel 1: Repeatable UV's

Channel 2: Free (Unity)

Channel 3: Free (Unity)

Channel 4: Baked UV's

Before Export Map Channel Info:

FBX Map Channel Info:

I assume for whatever reason the export removed Map Channel 2 (2:map) as it was empty? I need Map Channel 2 and 3 for Unity. I am to use 1 and 4.

Solution: I added a Map Channel 2 (Unwrap UVW) modifier to the stack and left the UV's there. The FBX contains all Map Channel's as expected.

Unfortunately, I was unable to find confirmation in FBX Help that on Export empty Map Channels are removed.

Can anyone confirm this?

poopipe

I don't think an empty UV set is invalid as far as the fbx format goes - that stuff is pretty flexible in general (would have to check the sdk docs). I'd expect it gets stripped on import as it would be silly to do so on export.

You're pissing memory away if you're using channel 1 and 4 and ignoring the middle 2 - is there a good reason for that?

ColMatrix

Hi Poopipe,

thanks for getting in touch. Yes there is, I need to keep the channels free for Unity. At some point I will be speaking to the dev's about leaving the first two channels for me and the rest for them.

Cheers