# Lightmap UV channel being ignored by Lightmass **URL:** \ **Category:** Rendering\ **Tags:** unreal-engine, Lightmap, Lighting, question\ **Created:** [October 27, 2016, 5:40pm UTC](https://forums.unrealengine.com/t/lightmap-uv-channel-being-ignored-by-lightmass/374646 "2016-10-27T17:40:14Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![anonymous\_user\_d5a7a023](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_d5a7a023](https://forums.unrealengine.com/u/anonymous_user_d5a7a023)\ **Post date:** [October 27, 2016, 5:40pm UTC](https://forums.unrealengine.com/t/lightmap-uv-channel-being-ignored-by-lightmass/374646/1 "2016-10-27T17:40:14Z")
I have a mesh which has 2 UV channels - the first one (UV0) is heavily overlapping for texturing purposes, and the second one (UV1) is a lightmap, and is not overlapping at all. I have set Lightmass Source Index to 1, and Lightmass Destination Index to 2. This should work, right? It is working on all the other meshes, except this one. “Generate Lightmap UVs” is disabled as well, however enabling this will fix the problem, but I do not want to rely on the generated UVs, as I have had problems with those before. You can download the mesh in question here: [Dropbox - File Deleted - Simplify your life](https://www.dropbox.com/s/paajomlrrgn6yrw/rooms2.fbx?dl=0) ---
**Author:** ![Tim\_Hobson](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Tim\_Hobson](https://forums.unrealengine.com/u/Tim_Hobson)\ **Post date:** [October 27, 2016, 5:46pm UTC](https://forums.unrealengine.com/t/lightmap-uv-channel-being-ignored-by-lightmass/374646/2 "2016-10-27T17:46:46Z")
Hi Arrays, You still need to set the Lightmap Coordinate Index to 1 in the Static Mesh Settings \> Lightmap Coordinate Index. > **[A new, community-hosted Unreal Engine Wiki](https://forums.unrealengine.com/t/a-new-community-hosted-unreal-engine-wiki/141494)** > > After over a year in maintenance mode, the official Unreal Engine Wiki is now permanently offline. These resources now live on a new community-run Unreal Engine Community Wiki — https://unrealcommunity.wiki/! You will be able to find content from... The Build Settings only generate the UV but do not automatically assign it in 4.12. I believe this was either correct in 4.13 or will be fixed in 4.14, which you can check in these versions since they are available in the Launcher. -Tim ---
**Author:** ![anonymous\_user\_d5a7a023](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_d5a7a023](https://forums.unrealengine.com/u/anonymous_user_d5a7a023)\ **Post date:** [October 27, 2016, 5:53pm UTC](https://forums.unrealengine.com/t/lightmap-uv-channel-being-ignored-by-lightmass/374646/3 "2016-10-27T17:53:25Z")
This fixed the problem. Thank you for the extremely quick response!