Hi guys.
I started studying UE a few weeks ago and I have a problem with lighmaps. The thing is lightmap density test texture don’t coinsides with actual UV channel. Take a look at the model on the pictures attached. As it visible - UV channel is Ok, but density testmap is distributed non uniformly, it is distorted in some way, while on other objects (floorslabs) everything looks and bakes right. This wrong distribution causes light (and shadow) bleeding right on the grid’s edges. I used the same steps to create UV channel and import model to UE for all these models, but the problem only occured with this tower. So, maybe someone has faced this kind of issue before and can give me an advise how to overcome it? Feels like the problem is in imoprted model, not UE. Thank you for reading and watching.
Pictures: Lit http://i.imgur.com/PIhywNA.jpg?1
Lightmap density http://i.imgur.com/E3ObxmH.jpg?1
UV Channel http://i.imgur.com/rediLFZ.jpg?1
Might be an issue with the UV channels, your mesh only has one UV channel while you would need 2. “0” is usually for the textures and “1” for the lightmap. Do the other models too have just one channel?
Could be an issue with the unwrap as well, with inverted faces and too many seams.
Firstly - thanks for reply
Faces’ normals are alright: http://i.imgur.com/pt1EtXo.jpg?1
Added second channel (just copied the first one): http://i.imgur.com/QQSZuP0.jpg?1
The same result =(((: http://i.imgur.com/TVh3DYw.jpg?1
By the way, I’ve had the problem before, with more complicated model: http://i.imgur.com/JXeN8Rk.jpg?1
http://i.imgur.com/GgrHANy.jpg?1
The first deduction was it is something wrong with geometry. The armchair was made by another person, I just adapted it for Unreal. That’s why I made that tower myself to test it and got bad result ( The situation really puzzles me. I do the same actions but aquire different results…
this does look like it might be a UV issue, if it is then just copying the first UV to make the second wont work because the lighting would be baked onto your mesh in the same way so will have the same shading errors, you will need to create a new UV specifically for the lightmap as they have different requirements to diffuse/texture UV’s.
also it looks like you “lightmap coordinate index” is set to 0 so its still using the first UV for the lightmap.
that’s not strictly true, on some models you can get away with using 1 UV for the textures and lightmap, for example you could unwrap a barrel to have just 3 UV islands that don’t overlap.
Just tried to build light usin’ second UV map - no difference occured…
There was another model of tower with similar problems. I didn’t know what to do, so I made another model from scratch with approximately the same shape. Nothin’ changed. What you’re seeing here is the second version of tower. I can create the same models for ever and maybe sooner or later next one will behave right, but that’s not a solution. I want to find the core of the issue.
Made another test object. Did it in empty 3ds Max scene. Didn’t even saved it. Put the model in Unreal… http://i.imgur.com/heRwi4U.jpg?1 http://i.imgur.com/pX3bRng.jpg?1 Even default grid texture wraps wrong…
Yeah, you’re right. It doesn’t need to be more then one, it just gives you a lot more control using 2 channels.
It seems to me that you have some Unwrap issues within max. What is your method of unwrapping? Do you do it manual? Do you use flatten mapping? Flatten mapping shouldn’t create issues, but other methods may have inverted faces. Those invertations are not the same as flipped normals on your model.
The quickest way to check your Unwrap for errors like this is to give it a checker map within the modeling tool so you can see potential problems before exporting.
I found what was wrong! The trouble was in 3DS Max FBX export. UV channel got distorted by FBX export’s triangulation process. After I triangulated it manually, exported to FBX and imported to Unreal, everything worked in a right way http://i.imgur.com/gIcHPRa.jpg?1, http://i.imgur.com/fA2llIx.jpg?1. What I actually did is - converted the model to EditableMesh, selected all edges, clicked on ‘visible’ button in ‘surface properties’ part of EditMesh parameters http://i.imgur.com/Bfh3mWk.jpg?1. Then exported the tower.
I found this solution here: Imported FBX meshes have broken UV's. Why is this? - Rendering - Epic Developer Community Forums. By the way, there are several options of eliminating UV distortion.
Thanks to haldolium and for your quick replies
