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Basic UV Editing within UE4 ?

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    Basic UV Editing within UE4 ?

    Hi guys,
    I'm experimenting with lightmaps and resolutions to get sharp shadows (for example window frames). For that its important to edit the lightmap UV to your needs (make the parts of interest larger).
    Wouldn't it be nice to have some basic editing features in Unreal Engine to scale, rotate ... UVs within the editor? So you can make changes without going forth and back to your 3d modeling program?

    What are your thoughts on that?
    Thanks and regards

    #2
    I think UVs just take practice, like anything else. Once you get the hang of them I don't think you'd be flipping back and fourth as much. It's just like modeling, we don't have proper modeling tools in UE4 but it's not really a huge deal.
    James Gallagher

    Architectural Technologist, P3Architecture Partnership

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      #3
      Thanks James, I know you can make great UVs while modeling. But what if you want to have this particular wall to have crisp shadows and not the other? You have to move around different stuff, rotate and so on. You simply cannot predict every UV you need to be larger or smaller?

      How do you approach things like that?

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        #4
        After messing with UV's for a while it's not difficult to set them up in your 3D program correctly beforehand. Like for example, I have something where there's a large UV island for an area on the mesh that doesn't need much UV detail, or I have some very small UV islands that need more detail--I know to adjust the scale of those islands beforehand even before sending to UE4. That's just part of optimization, I can't think of any situation where I'd be tinkering with the UV's

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          #5
          Thanks darthviper for your answer. What happens when your lighting changes and now you spot an UV island, that you made small during modeling but now need in large scale for nice shadows?
          But I understand your point by doing the thinking about lighting and UV stuff beforehand.
          Last edited by egalegal; 09-14-2016, 01:38 PM.

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            #6
            Once you do UV's a lot, you should be able to catch that type of thing beforehand. Having them be too small means the lightmap will have to be higher resolution for them to get more coverage. So that's one of the things you have to consider when you do your UV's--Will the object have to have a really high resolution lightmap just to get enough detail on these small parts, or should I increase their size so that I can have the smaller lightmap even if it means the pixels aren't a uniform size on the object?
            I see that issue all the time with Automatic Flatten UV's because it only splits by angle, so you can end up with very small UV islands. It's best to do them manually and keep an eye out for problem areas for the lightmap.

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              #7
              Auto unwrap is a charm.

              If the 1st try results in too many small islands... instead of optimizing or unwrapping manually, I prefer to break the object in multiple parts and auto-unwrap each parts with my script.

              Doing manual unwrapping would drive me crazy.

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                #8
                What dou you mean with auto unwrap? Within UE4?

                But how does the software know, that you need that specific face of the wall as an huge UV island to get most out of the lightmap?

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                  #9
                  Auto flatten looks at the angles between surfaces and splits them that way, but very often splits things too much which gives bad results, especially if you have things like rounded corners because it can split the small polygons on the edges off to their own islands and that makes issues.

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                    #10
                    Yea I agree with that. It's a problem when you want to chamfer edges. I really miss something like raytraced round corners in offline renderers. [MENTION=320538]egalegal[/MENTION] The auto-unwrap/flatten script is steamroller for 3ds max!

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                      #11
                      Originally posted by egalegal View Post
                      Thanks James, I know you can make great UVs while modeling. But what if you want to have this particular wall to have crisp shadows and not the other? You have to move around different stuff, rotate and so on. You simply cannot predict every UV you need to be larger or smaller?

                      How do you approach things like that?
                      I'm a bit late with my answer. Additional to what the other guys said, you can overwrite the lightmap resolution for individual meshes. If you want one particular mesh to have more detailed shadows than all the other instances then search in the detail panel for "overwrite lightmap resolution" and set it to a higher value.

                      In fact it is good practice to set the lightmap resolution in the mesh browser as low as acceptable and only increase it for the instances that need a very detailed shadow.
                      www.s-dot.de/viz
                      ArchViz User Interface :: UE4 Marketplace.

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