Error: Lightmap UV are overlapping by 40%

[Trugb35]

Align Uvs

Also when you have a mesh that is square. The Uvs on the second channel needs to flat and aligned. Make sure there is a 2 pixel spacing between each island. At least that is how it was done in UR3

@BallisticGE0RGE;4206

As you can see here…

://i.imgur/9yug5WO.jpg

I did that, and it still fails. No idea why.

Bring it into 3ds and doing the UV there fixes it. But I wonder why it doesn’t work in in Generate UV Script, am I doing something wrong? I do save the file, and the UVs do look different…hmm…

[Jambax]

Make sure you change the Lightmap UV Coordinate Index to use Channel 1, otherwise you’ll still be using channel 0. (Surprised nobody said this yet)

[PuckerFactor (PukkaFactor)]

Generating UVs in UE4 only works if you are using a single texture or material applied to the mesh. If you have meticulously unwrapped and painted your texture to match the UV’s you created in your 3D app, it’s going to be all undone with UE4’s UV generation. The best practice is to unwrap properly in your 3D app with enough space surrounding the UV’s and to create a 2nd set for the UV lightmap channel.

[starseeker]

Sorry, of topic a little, but related.

Doesn’t UE4 now support full dynamic lighting. Why do we need to use baked lights? If you have full dynamic lights set up, do you still need to make lightmaps?

[anonymous_user_9538cf55]

UVs

give me some help , i dont know how you can use the Engine for creating the UVs automatically ??

[Sam_Deiter]

@;14727

Sorry, of topic a little, but related.

Doesn’t UE4 now support full dynamic lighting. Why do we need to use baked lights? If you have full dynamic lights set up, do you still need to make lightmaps?

No you would not but being fully dynamic will greatly limit the hardware that your game can run on. Light maps are great because that can give you some very good looking results that run very fast no matter what hardware is running them.

[anonymous_user_923c79df]

@DIAB;44377

give me some help , i dont know how you can use the Engine for creating the UVs automatically ??

double click onto your static mesh -> window -> generate unique uvs -> select the 2nd channel (Uv channel 1) -> apply

But I would recommend you to just do it in your 3d program

[Gibdion]

So can you have overlapping UVs for textures as long as you provide a second UV channel with no overlapping UVs so UE4 can build light maps onto that that channel?

…edit
Actually yes I can confirm this.

[neighborlee]

What,and where in blender is LightPack?

@EssJayDubDub;11988

I was encountering this problem on my meshes until I found the Light Map Coordinate property inside the UE4 static mesh editor. By default after importing it was set to 0 (aimed at my diffuse UV channel) and had to be set to 1 (aimed at my lightmap UV channel). After changing this I no longer got the lighting build error and the shadows are appearing correctly.

In my workflow I use Blender to create my meshes. Each mesh has 2 UV channels, the first for diffuse texture (where overlap is fine) and the second for lightmap (where overlap is a problem). In Blender you can generate your lightmap UVs via LightPack, if you specify a margin of 1.0 then you will definitely not have any overlap. The key part of the Light Map Coordinate setting is to make sure that UE4 is using the correct UV map.

Where is lightpack ? I searched web for anything related to this and came up completely empty.

[anonymous_user_923c79df]

@neighborlee;197724

Where is lightpack ? I searched web for anything related to this and came up completely empty.

Just select the mesh - space bar - lightmap…

[neighborlee]

@;197730

Just select the mesh - space bar - lightmap…

Is this a new feature, just wondering because pressing spacebar and it wasn’t there, so I had to search for it. Very odd its buried in that way, but ty for heads up

NEVERMIND, its just under uvunwrapping > LIghtmap pack

cheers
nl

[anonymous_user_8da9c75f]

Thanks .
To elaborate… In Blender, I selected the mesh. Hit A on the keyboard and searched for Lightmap Pack. Selected it from the search results. When it opened I kept the Lightmap Pack defaults and hit OK. I then re-exported the fbx and then reimported it into UE4. I actually deleted the existing mesh and all of the graphics for it and reimported, but probably not necessary to delete first. It worked for both meshes giving that error.
Thanks again.

[alto_andre]

Thank you for the tips! I have the same problem so I tried setting the UE4 newly generated light map UV in the index and dragging the blueprint instead of the mesh directly, but the error still persists
Is there something I’m missing?

[ant1fact]

@;3948

You have to:

1. either create a 2nd uv channel (when you dont have one)
2. adjust the 2nd uv channel so that the uvs arent overlapping

Which 3d program do you use, because when it’s blender, I can tell you how to fix it

I just stumbled upon this thread and I DO use Blender and I would love to hear your fix for this issue!! PLEASE <3 8)

[Wammbo]

Aloha dear Community,

am new to modeling (3ds ) and i want to do it the right way. I don’t want to get sloppy in my workflow.
I understand the way how to get the second UV Channel for Lightmap. But i feel a bit uncertain about some stuff so i want to ask.

1. Is it a common task to overlap or flip “UV island” to save Texturespace in Channel 01?

2. Would a professional do the same task (overlapping / flipping in Channel 01 and Lightmapping in Channel 02) ? Or there are any other technics / workflows out there?

i just need a conformation to be sure for my self.
Thanks in advance.

best regards

Wammbo

[CGhenriquez]

@;3948

You have to:

Which 3d program do you use, because when it’s blender, I can tell you how to fix it

Do you still know how to fix this in Blender? haha ^^ (said the 2016 newbie)

[sstefan4]

@anonymous_user_923c79df

You have to:

1. either create a 2nd uv channel (when you dont have one)
2. adjust the 2nd uv channel so that the uvs arent overlapping

Which 3d program do you use, because when it’s blender, I can tell you how to fix it

hey can u help me , i use blender and i have the same issues (uv are overlapping by 59% )

[darthviper107]

@Estebantr

hey can u help me , i use blender and i have the same issues (uv are overlapping by 59% )

https://docs.unrealengine/en-us/Engine/Content/Types/StaticMeshes/LightmapUnwrapping

[28victor]

@anonymous_user_923c79df

You have to:

1. either create a 2nd uv channel (when you dont have one)
2. adjust the 2nd uv channel so that the uvs arent overlapping

Which 3d program do you use, because when it’s blender, I can tell you how to fix it

Could you explain how to do it in blender?

[luca_belp]

Simply setting Light Map Coordinate to 1 fixed my problem!!! Thanks!