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    UV Wrapping

    Hey Everyone,

    So I have a quick question about the UV Wrapping error. I've been making some modular meshes in Blender and ran into the UV Wrapping error today. I was trying to make a basic stair case and when I built the lighting in engine I got the error and the Stairs had a weird black effect. Here's a few screens.

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    So I researched UV wrapping and it said that it is because I am scaling out of the 0,1 UV space. The thing is tho that I've made several meshes before this that were scaled out of the 0,1 UV space and I've had zero problems. I'm just wondering why I've run into this problem with this mesh. Any help would be great.

    Thanks

    #2
    are you using that UV for your lightmap? while you can go outside the 0-1 space for your texture UV's you cant for lightmap UV's. also that UV is not layed out very well, you might want to think about rearranging it.
    Last edited by smokey13; 09-23-2014, 02:12 AM.

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      #3
      To add to Smokey's response.

      You'll definitely want to make sure that you're using a second UV for your lightmap. In this specific UV you cannot scale outside the 0,1 space because anything that is scaled out of this area will be rendered black or cause some overlapping on other mesh faces like you're seeing here. However, it is perfectly OK to have your texture UV scaled outside of the 0,1 space.

      I'm not sure about your previous meshes that you appear to have had no issue with, but with this specific case this is the issue.

      If you have any questions please feel free to ask!

      Tim
      Tim Hobson | Learning Resources | Epic Games
      UE4 Documentation

      Comment


        #4
        Hey guys,

        I'm not using that uv as my lightmap, at least not intentionaly. I made a second uv channel for the mesh just like I did for the others. I must be doing something weird. I'll play around with it when I get home. I know it's a terrible layout I was just using it for the screen. I didn't want to set the whole thing up (again) just to have to redo it to fix the problem.

        Thanks for the replies, I really appreciate it.
        Last edited by Tayber415; 09-23-2014, 11:19 AM.

        Comment


          #5
          To double check that you're using the correct UV for the lightmap. Open the mesh in the Mesh Viewer and in the details panel to the right find the option that says "Lightmap Coordinate Index" and make sure that it is set to 1 instead of 0. This will be your Lightmap channel.

          Tim
          Tim Hobson | Learning Resources | Epic Games
          UE4 Documentation

          Comment


            #6
            Hey Tim,

            I didn't know that they could be set like that. Thanks I'll try it when I get home.

            Comment


              #7
              Hey Tim,

              Sorry for the late reply. I just wanted to let you know that it was set to UV 0 as the lightmap. So as you said i set it to UV 1 and that fixed it. Thanks so much for the help.

              Comment


                #8
                @Tayber415, your uv's are also wrong, before unwrapping, be sure you have rotation and scale apply in Blender, then try Smart UV Project, and should give you betters UV sets. You can do the same for lightmap, second uv set, and maybe you can put island margin to 0.1 and and angle limit to 1.

                Comment


                  #9
                  Originally posted by Tim Hobson View Post
                  To double check that you're using the correct UV for the lightmap. Open the mesh in the Mesh Viewer and in the details panel to the right find the option that says "Lightmap Coordinate Index" and make sure that it is set to 1 instead of 0. This will be your Lightmap channel.

                  Tim
                  Hi there,

                  I have been having no luck getting my blender fbx ( fbx v 7.x is ok ?) model imported into ue4, to show more than 2 channels, as when I double click on object to bring into object browser (name ?),it says it only has 1 channel,,,,does it really though ? Is it really so simple as you outlined to alter the setting on right side to 1 not 0 for uv channel 2 , or have I setup my blender object incorrectly that its showing 1 channel only ?

                  thx anyone/tim ;()

                  nl
                  Solo but Seismic - feel free to apply
                  https://neighborlee1.wixsite.com/theheartseed

                  Comment


                    #10
                    If you're just looking to add a UV channel you can do this in the engine much more easily now with the new Generate Lightmap tool.

                    Open your mesh > Build settings > Select LM resolution > Apply changes > Locate Lightmap Coordinate Index and change this value to 1 and you've now got your generated Lightmaps.

                    As for the stuff with Blender I'm not sure since I've not really used it. There could be something up there I'm just not sure. The method above will get you the Lightmap if that's all you need.

                    Let me know if that helps or not.

                    Tim
                    Tim Hobson | Learning Resources | Epic Games
                    UE4 Documentation

                    Comment


                      #11
                      Originally posted by Tim Hobson View Post
                      If you're just looking to add a UV channel you can do this in the engine much more easily now with the new Generate Lightmap tool.

                      Open your mesh > Build settings > Select LM resolution > Apply changes > Locate Lightmap Coordinate Index and change this value to 1 and you've now got your generated Lightmaps.

                      As for the stuff with Blender I'm not sure since I've not really used it. There could be something up there I'm just not sure. The method above will get you the Lightmap if that's all you need.

                      Let me know if that helps or not.

                      Tim
                      Right now Im afraid I don't have current subsciption, and I've heard that this 'new' feature is in 445..Im pretty sure I have 441, unless you think it also works in the prior v I have, I'll check later on just in case.

                      ty
                      nl
                      Solo but Seismic - feel free to apply
                      https://neighborlee1.wixsite.com/theheartseed

                      Comment


                        #12
                        Okay I just tried the 'generate UV' for 4.4.3 thinking that might help, but while it showed a 'uv channel' to apply them to, my object only has 1 channel showing as '0'. How do I add a new channel ?

                        Hoping this will fix my issue (

                        ty anyone
                        nl
                        Solo but Seismic - feel free to apply
                        https://neighborlee1.wixsite.com/theheartseed

                        Comment


                          #13
                          Generating UVs prior to 4.5 can be a little iffy sometimes. Even in 4.5 you would have to have a properly setup UV0 for your texture to get a good results with Lightmaps.


                          So, with that, In 4.4.3 and prior you will need to go to the Menu bar > Window > Generate Unique UVs >

                          This will open a new tab under the details panel. There will be two options. create new which will unwrap for you but does a fairly poor job that can cause artifacts in your lightmap that is baked and Layout using channel 0. This is the best option because it will reorganize your LMs based on how you unwrapped your UV0 for your texture. It will repack and organize within the 0,1 space.

                          Select Layout using 0 channel and set the channel to save results to as UV Channel 1. This will then create the lightmap UV based off the UV0.

                          Let me know if you have any questions.

                          Tim
                          Tim Hobson | Learning Resources | Epic Games
                          UE4 Documentation

                          Comment


                            #14
                            Originally posted by Tim Hobson View Post
                            Generating UVs prior to 4.5 can be a little iffy sometimes. Even in 4.5 you would have to have a properly setup UV0 for your texture to get a good results with Lightmaps.


                            So, with that, In 4.4.3 and prior you will need to go to the Menu bar > Window > Generate Unique UVs >

                            This will open a new tab under the details panel. There will be two options. create new which will unwrap for you but does a fairly poor job that can cause artifacts in your lightmap that is baked and Layout using channel 0. This is the best option because it will reorganize your LMs based on how you unwrapped your UV0 for your texture. It will repack and organize within the 0,1 space.

                            Select Layout using 0 channel and set the channel to save results to as UV Channel 1. This will then create the lightmap UV based off the UV0.

                            Let me know if you have any questions.

                            Tim
                            Ah very nice, ty so much Tim ;_

                            nl
                            Solo but Seismic - feel free to apply
                            https://neighborlee1.wixsite.com/theheartseed

                            Comment


                              #15
                              Originally posted by Tim Hobson View Post
                              Generating UVs prior to 4.5 can be a little iffy sometimes. Even in 4.5 you would have to have a properly setup UV0 for your texture to get a good results with Lightmaps.


                              So, with that, In 4.4.3 and prior you will need to go to the Menu bar > Window > Generate Unique UVs >

                              This will open a new tab under the details panel. There will be two options. create new which will unwrap for you but does a fairly poor job that can cause artifacts in your lightmap that is baked and Layout using channel 0. This is the best option because it will reorganize your LMs based on how you unwrapped your UV0 for your texture. It will repack and organize within the 0,1 space.

                              Select Layout using 0 channel and set the channel to save results to as UV Channel 1. This will then create the lightmap UV based off the UV0.

                              Let me know if you have any questions.

                              Tim
                              Well crud )

                              I did as you suggested and I'm getting: layoutUV failed: couldn't convert to DVDXMESH.

                              I wonder if its because I exported using fbx binary 7.4 instead of version 6 ascii based ??

                              Thx for helping with this Tim.

                              cheers
                              nl
                              Solo but Seismic - feel free to apply
                              https://neighborlee1.wixsite.com/theheartseed

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