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Exporting from SpeedTree with section groups

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  • Exporting from SpeedTree with section groups

    I am currently trying to export the spines only from trees made in SpeedTree into Houidni.
    The issue I am having is that I am unable to get each section of branches as individual groups.
    What export settings would I need to apply to get this to happen?
    At the moment I am getting all spines but each spine is in a seperate group instead of being grouped into their own layer/section.

  • #2

    If you are using the v7 SpeedTree modeler, then it just exports the spines out as a big bundle of spines. However, if you are using the v8 version of the SpeedTree modeler, then in the Export Settings you just need to set the 'Group by' to 'Hierarchy'.

    Hope this helps!


    • #3
      Thank you for the reply.
      I am using V8.2.1
      I have tried this with all different settings. If I choose 'Hierarchy' then there is also 0-9 different options of how I want the hierarchy to be structured.
      0 - 'All'
      1 - 'Trunk'
      2 - 'Major Branches'
      3-9 have no description at all.

      So I tried them all:
      If I use 'All' option then I only got the trunk spine and no other spines.
      If I use 'Trunk' I also only get the trunk spine showing and no other spines.
      if I use 'Major Branches' then I get the trunk spine and the first section of the branches spine. But I am still missing 2 sections of branches.
      I then tried option 3-9, this is based if I manually want to assign the section amount, which in my case is 4. So in my case 4 would be the optimal and I do get all the spines into my scene. But the issue again is that they are not grouped by section.
      It feels like I am missing something simple..


      • #4

        When you said that you are "missing 2 sections of branches", what are describing as sections? It will be easier to help if you send some screenshots.

        Also, here is a link to our documentation page about the export settings, this may help explain it better:


        • #5

          Click image for larger version  Name:	Capt2ure.PNG Views:	0 Size:	468.5 KB ID:	6699Click image for larger version  Name:	Capture.PNG Views:	0 Size:	36.9 KB ID:	6702
          My tree in SpeedTree. This is what my tree looks like with all splines connected.
          In the picture we see 4 different sections, The trunk, big branches, bifurcating branches, little branches . So for 4 sections I want 4 groups. It seems that SpeedTree supports this but I can't get it working.

          Click image for larger version  Name:	Ceweeapture.PNG Views:	0 Size:	196.9 KB ID:	6700
          This is what I mean by 2 sections of branches missing. This is when I tried the "major branches" hierarchy. It only took the trunk and the big branch section.

          This is how the structure looks like in Houdini with the tree with all the splines:
          This is not very easy to work with.
          Click image for larger version  Name:	Captu3233re.PNG Views:	0 Size:	33.4 KB ID:	6701
          This is what I want:
          Click image for larger version  Name:	nicece.PNG Views:	0 Size:	3.4 KB ID:	6703
          The above picture shows the structure of a different tree from SpeedTree, and that is the structure I want.


          • #6

            The docs page Sonia posted earlier explains the hierarchy level with pictures. Branches are hierarchical, and when you export grouped in that mode, you can pick the level at which the tree is no longer split apart. 0/All is all in one object. 2/Major Branches means the trunk is an object and each major branch is a separate object that is a child of the trunk. The time it takes to save and load an alembic file is very dependent on the total object count, so this lets you keep that to a minimum but also split the tree up as much as you need.

            Spines are part of that hierarchy, and are only available when exporting grouped by hierarchy. You get a separate spine up through the hierarchy level you choose. When deforming the tree, you might not care about individual leaves, but you want to move the branches, etc. And again, exporting up to a certain hierarchy level this prevents a tree exploding with thousands if not millions of spine objects. Grouping them by generator would lose all of the hierarchy information (parent/child relationships, etc).

            It sounds like you're wanting all of the spines in a tree no matter what, but grouped differently. With no parent/child relationship, or would you need that in some other fashion? Could you describe what you're going to use that for? It could help us to know this when answering.

            There is one alternative that is available when exporting to Alembic and importing to an app that makes it easy to get at all the Alembic data (which Houdini definitely is). If you tick the box in the export dialog for "Extra attributes", you will get lots of additional information in the tree. When you unpack the data, you'll see tons of extra information in the primitives. You can sort the individual SpeedTree nodes in that object by using the 'hierarchy' value. 'hierarchy_level' is basically the grouping you want. And the 'spine' value contains a string with all the spine points. You'll want to merge these based on 'hierarchy' to avoid duplicates. I am not an expert in Houdini, but I have assisted some customers who wanted to export a single object for speed, and then rip the tree apart (including spines for deformations) using this information.

            Hope this helps


            • #7
              Thank you so much for the help both of you!
              Ticking the "Extra attributes" and unpacking afterwards in Houdini gave me the 'hierarchy_level' of each section. So in my case with 4 different sections I get level 1-4 in correct order. This is very helpful as my original idea was to assign a level attribute by hierarchy in Houdini but it seems that I am getting it automatically so that's nice.

              Thanks so much!