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Procedural foliage spawner on Landscape LODS

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    Procedural foliage spawner on Landscape LODS

    Hello, I have an issue on our project.
    We have an open world island, and we are having some problems with far trees.

    We imported the heightmap in UE4 and made a landscape from it, we are using world composition to separate it in tiles.
    Now the problem is: when I spawn trees with the procedural foliage spawner tool everything it's ok in LOD 0.
    When the LOD1/2 ecc. come in , the trees or everything I spawned with the tool will disappear because the landscape doesn't have collisions, so the spawner will not spawn anything.

    To solve this, I tried to export my terrain tile LOD in Maya and reimport it with a collider which has the same topology as the lod mesh.
    This solve the problem, but the trees will change position when the LOD comes in, because landscape collision is different from the collision I generated for the tile!

    Someone knows a workaround for this? Exporting the landscape collisions could work, or maybe I am missing something.


    Below you can see what I mean for different position of the trees spawned.
    This is the view with NO LODded terrain

    Click image for larger version

Name:	NOLOD.JPG
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Size:	66.2 KB
ID:	1176709

    This is when the LOD comes in (two meters from the first view)

    Click image for larger version

Name:	LOD.JPG
Views:	1
Size:	57.5 KB
ID:	1176708


    Thank you for the help!
    Last edited by Iacopo Antonelli; 03-21-2016, 12:31 PM.

    #2
    No solutions?..

    Comment


      #3
      I have looked at this thread but I have struggled to see what exactly you are pointing out in the images in relation to what you wrote.

      The only difference I see in the image is some weird vertical strip mesh that kind of looks like a stretched thin tree. It is not clear what the issue is there since it is only in one image and most of the trees look the same in both images other than some DOF artifact that I see in both images.

      The foliage tool does not dynamically trace the landscape and reposition trees based on your collision, all of that is saved and prebaked at simulation time. So it is probably not collision related at all.

      The only issue with the foliage tool and landscape LOD that I know of is that instances may float above the ground a bit as the landscape LODs. I thought we had fixed that at some point though.

      Most likely you have some content issues with your foliage LODs. are they speedtre billboards or what? perhaps you are using some nodes that do not work for foliage, such as actorposition for some wind or projection in the shader?
      Last edited by RyanB; 03-23-2016, 12:19 PM.
      Ryan Brucks
      Principal Technical Artist, Epic Games

      Comment


        #4
        I am not using foliage tool. I am spawning it with a procedural foliage spawner volume, copied and pasted in the LOD scene and in the main scene (with the same position and scale obviously)
        Simply it will delete the foliage spawned with the spawner (which requires COLLISIONS to spawn foliage)
        I tried a workaround as I said, but the foliage is not in the same position

        Comment


          #5
          I meant the procedural foliage tool. It does not re trace collision for separate LODs it does that when you simulate the procedural foliage volume.

          I am not sure what you mean by having two levels with different LOD as normally LODs transition in the distance.

          What exactly is different in your second level where it does not work?

          Are you talking about the LOD of the terrain or the foliage meshes?
          Ryan Brucks
          Principal Technical Artist, Epic Games

          Comment


            #6
            I am talking about landscape LOD which separate each tile LOD in a separate scene

            Comment


              #7
              Are you talking about World Composition, which is actually generating separate LODs for the entire level?

              If so, we never intended to be able to render procedural foliage into the whole level LOD. The entire point of that feature is to render the foliage into the flat 2d LOD texture of the entire level. That is why when you go to bake whole level LOD it gives you the option to bake both grass and foliage separately. If you want to keep foliage meshes then don't use the whole level LOD feature and simply rely on the regular landscape LOD and cull distance settings etc.
              Last edited by RyanB; 03-23-2016, 02:03 PM.
              Ryan Brucks
              Principal Technical Artist, Epic Games

              Comment


                #8
                Ok. This is really odd in my opinion. Regular LOD are more costly than level LOD, I will find a workaround. Thank you very much Ryan!

                Comment

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