Im trying to Light my scene and I’m getting a light error saying I have overlapping UV’s, so what I normally do is go into the static mesh editor, change the UV channel to channel 1, and I preview it and it shows no overlapping UV’s. I click save and close the mesh editor. And it goes right back to the UV channel 0. When I just changed it to UV channel 1. How can I fix this bug? I also import static meshes with, Generate UV set turned on and it doesn’t make me a second UV channel like it should. Any idea on how I can fix this?
Your not changing the UV channel your just “previewing” it as you say, and when you re-open it it goes back to the default, 0. Are you using Maya? Most modelling programs dont even allow for multiple UV channels and what your seeing is just unreals calculated UVs for some other stuff.
That said, overlapping UVs is generally considered a “nothing to worry about” issue unless you have noticeable artifacts, then the object should be remodelled/uvunwrapped, retopologized.
Hope this helps Don’t forget to accept an answer that best clears your question up or answers it so when the community finds your question in the future via search/google they know exactly what you did to fix it/get it going.
Yea, Im using Maya, the thing is, theirs no overlapping UV’s in Maya, and in Unreal it says its overlapping, but its not. Im getting a ton of artifacts as well. The objects get black spots and the scene wont light correctly. What should I do? Is it because my meshes are combined into one mesh?
From your previous posts I believe what is happening is the bleeding of the lightmaps from different sets of UV coordinates.
UV lightmaps, like albedo maps, are calculated by default on a 0 to 1 scale. UE4 attempts to calculate your UV’s every one unit of measurement. Sometimes, if you have your UV’s too close, the space is too small and therefore UE4 attempts to calculate close UV’s at the same coordinate space. This can cause black spots, blown out lighting, and a number of other issues.
If you would please link me a screenshot of your UV’s and the issue you are experiencing inside of UE4. I will then continue to investigate this issue further.
In the meantime, please take a look at out documentation on how to unwrap Lightmap UV’s and some troubleshoots you can do in order to avoid the artifacts.
Here’s my image of one of my pieces, the Uv’s are layed out automatically, because Im using a gold material, don’t need it to be plane mapped and stuff.
In my second image my Uv’s aren’t over lapping, and when It’s in unreal, it says its overlapping, but It’s really not, in maya. It wont let me create a second UV channel when I have auto generate Uv maps turned on. I have only one uV channel.
For my other pieces, I have them combined, each piece has UV’s that were fine. The pieces are combined because its easier to import into unreal, I have like 20 combined objects, could grouping them be better for export? But yea I click on the UV channel 1 for that object, it has a second UV channel, but some of my other meshes don’t. So I choose UV channel one, like I read online. I check the UV’s and Unreal does a good job keeping it. So I save it out. Close the mesh editor, and do another build. It still says its overlapping. So I go into the mesh editor and its set to 0, when I set it to 1. So I set it back to 1, and save it. And go back into the mesh editor and its back to 0. I don’t know why It’s doing this, and why I keep getting these little bugs, any ideas, on how I can fix this?
I created a test to demonstrate different aspects of how you could possibly be getting these errors.
1.) After unwrapping, if you select all of your uv’s and you relax them a bit this could possibly solve your issue. There is no telling from the image you posted if you have one or many uv’s hiding under others. This should help eliminate that issue.
2.) I created a test sphere in Maya and then automatically unwrapped it. You can assign another UV channel while using Automatic unwrapping.
I had to actually cut up the original automatic unwrap just to get something close to the result you had. I know I am using Maya 2015 so I realize Autodesk may have changed the way it unwraps.
Then I imported this into UE4. I kept everything default except for I assigned the lightmap coordinate index to 1.
The cylinder imported with the above screenshots is on the far left. The one in the middle was automatically with no seams on the surface, just on the edges where the extrudes take place. The one on the far right is done with planar mapping and with increased lightmap resolution.
I believe what you are experiencing is a workflow issue. The overlapping UV’s could be a result of UV padding as outlined here.
I can’t make my UV’s outside the 0 to 1 space? That’s whats giving me overlap errors. And how do I make Unreal keep at the second UV channel, the 1, instead of 0. Because it wont save at 1 for me at all.
Im Not using Mudbox, I’m using Maya 2016, and Unreal 4.9. I just want to change my UV channel, and have it save, it will fix all of my problems. But it doesn’t save for me. Is there any way to fix this?
Im Not using Mudbox, I’m using Maya 2016, and Unreal 4.9. I just want to change my UV channel, and have it save, it will fix all of my problems. But it doesn’t save for me. Is there any way to fix this?
I realize you are not using mudbox. As mentioned above I do not know why this issue is happening. I was attempting to provide more information on how UV’s can be handled outside the 0 to 1 scale. This is also valid in Maya as you can change the size and scale of your grid to incorporate objects that fall within the edges of your grid.
From your screenshot I see many of your uv’s crossing from one coordinate UV space to another. So if you have a face that has it’s left side in one square and the right side in another there will be issues.
As per your question and comment above I was attempting to answer that.
" I can’t make my UV’s outside the 0 to 1 space? That’s whats giving me overlap errors."
I am still investigating why your channels are not persisting through saves.
Oh, didn’t see you said Mudbox, sorry about that. I reduced nearly halve my errors by making the UV space bigger. Which helped me a lot. Let me know if you can find out the bug, thanks.
I tried to recreate the issue of your Light Map Coordinate Index not persisting by using the same project in the screenshots above.
These are the steps I used.
1.) Opened the project and went to one of the half spheres.
2.) Double clicked on the asset to open it’s Detail Window.
3.) In the details panel I went to Static Mesh > Light Map Coordinate Index and changed the value from 1 to 2
4.) I then saved the asset by using the save with the floppy disc above it in the same window. It is located in the top left.
5.) I then closed that window and saved all under File > Save all in the main viewport
6.) Closed the project
7.) Reopened the project
8.) Went to the same asset where the Coordinate Index was changed.
9.) Result : Number was still 2.
Let me know if this is different from the steps that you took. Also if you use the above mentioned steps, does the index persist?
Hey, sorry about that, took a break from my computer for a few days, I’ll try the steps and see if it works, and I’ll let you know how it works, thanks.
Yea, the light map coordinate under stays where I want it to, like 1, 2, or 3. But the UV chanel won’t stay at UV channel 1, or my channel 2, or my channel 3 that I created. Reverts right back to 0 when I save it and close the mesh editor.
The window where you can preview your mesh is intended for editing and previewing. The lightmap coordinates persist because you are assigning that that index to your object. The UV channel will, by default, always return to 0 after you have saved and opened the window again because that preview function is embedded within that windows framework.
UV Channel 0 is the starting point, or base point, of a static mesh within the editor.
This is intended behavior of the editor. If I entered a bug for this, I would hear back the same information as given above.
Thank you for reporting this, however this is a function of the editor.
How do I fix my light map issues? Cant fix it in maya, can’t fix it in unreal, because I know Unreal is supposed to create a light map to best fit your mesh and texture and save it. I have like 20 assets, all Uv’ed laid out nicely, no overlapping. So I combine my meshes, say it’s a Column, so I combine them, so I can export it to Unreal, so I don’t have to pain stakeingly re-assemble my meshes one by one in the editor trying to get it in the exact spot. So I import it, and build and it says it’s overlapping. And it’s making my statics have black spots and won’t light correctly. I mean it’s a huge scene, I have like 60 meshes combined so it could import properly.
Could we fix this by exporting it out as a group, instead of it being combined? So Unreal can read it separately and I wouldn’t have to spend 5 days trying to re-assemble it.
Or could we use the send to unreal button with all of my meshes separately and have one static or mesh piece. I’m not sure if that’s the best, like what if the pieces need to move or break, like a fight scene, would that be a good option?
