Tree LODs guide

To have trees show at a distance you will need something called LOD trees. These are simple models showing the whole tree. I’ll go through how to prepare them and get them to show in the worldspace. In this example I will use new trees, if you are only using original Skyrim trees the proses is much simpler.
This guide by FR_dZastrX also covers this subject and more, I suggest reading it as well.

Tools needed:

The steps I will go through in this guide:

  • Add trees in the CK
  • Worldspacetreelod image
  • _lod_flat.nif files
  • UV-maping
  • Generate lod trees in CK
  • Fix btt files with TESEdit (if worldspace is larger than +/- 32 cells)


Adding new trees in the Creation kit

  • First you have to add the tree nif file right folder. The original trees are in Skyrim/data/meshes/landscape/trees, but you can make your own folder if you wish.

In Skyrim, trees have animated branches and in the CK they are a separate group of objects, you can find the trees under WorldObjects/trees in the Object Window. Note that only trees with animation can be added as trees.

  • To add a new tree right click in the list of trees, select new.
  • Give the new tree a unique ID, and press Edit to select the tree model. Navigate to the folder where the tree is located and select it, press open and OK. The new tree will now appear in the list.

You can change the amount of animation if you like, to do this, right click on the new tree in the list, select edit, and play around with the Trunk Flexibility, Branch Flexibility, Leaf Amplitude and Leaf Frequency.

Making the Worldspacetreelod.dds file
Every worldspace needs a tree image atlas, composed of all the trees in that worldspace for tree lods to work. If you are only going to add new trees to your own worldspace I suggest making a separate worldspacetreelod.dds. If you like to use your new tree lods in the Tamriel worldspace you need to change the original TamrielTreeLod.dds file.

  • First you have to have an images of the trees you wish to use. I suggest using either Nifscope or the CK preview. The coloring and shadow are different between the two, choose which ever you like best.
  • In Photoshop add the tree images in separate layers (this way you can move them easily later) and clean up the background color (you can do this by hand or use the color select tool). This needs to be done for all trees you want to have lods for.
  • When you make the actual worldspacetreelod image the size must be 256, 512, 1024, 2048 or 4096, but width and height don’t have to be the same.
  • Add in the new tree images, scale down if needed and make sure there are no overlaps between different trees.

In this example I also added images of the original Skyrim trees.
LodtreesGuide1
Once you feel happy with the trees you added you need to add an alpha channel to see only the trees in game and not the background.

  • First select all your tree layers and duplicate them. Then merge the duplicated layers to one layer (but leave the original trees as separate layers!)
  • Go to Filter/Blur/Average and make the layer completely white by enhancing the Brightness or Levels (Image/Adjustment/Brightness or Levels).
  • Select the whole layer (Ctrl A), copy (Ctrl C).
  • Click on Channels (next to Layers), click the right most symbol, select New Channel. Call it Alpha 1 and click “Masked areas”, this will give you a black alpha channel.
  • Select the Alpha channel, paste (Ctrl V). You may have to move the alpha image so it covers the tree image (press V to select the move tool, then move with arrows). When you are happy with the position you can deselect, and deactivate the alpha layer.
  • You can now delete the merged white layer of the trees.
  • Flatten image, then save as YourWorldspaceTreeLod.dds with these settings: DXT5 ARGB interpolated alpha, generate MIP maps 10. (In place of YourWorldspace choose the name of the worldspace you wish to make tree lods for).
  • Move the image to Skyrim/Data/Textures/Terrain/YourWorldspace/Trees.

lod_flat nif files
The tree images you just made must have a model file to show them, for this we use very simple lod_flat models that are just two plains.
LodtreesGuide2
Unless you know how to make the model yourself (look at this guide if your interested), I suggest using the models available for the Skyrim trees (or the ones GKB or Ztree (soon to be released) made).
All such files are called TreeName_lod_flat.nif. You can extract them from the Skyrim – Meshes.bsa (using BSAopt). The _lod_flat.nif models are of different sizes and it’s some work to find one that fits perfect. But don’t worry to much, you can scale the model in NifSkope.
I usually add both my new tree and the the _lod_flat.nif I will use in a test worldspace, and if needed scale the to _lod_flat fit the new tree in size. You can see the amount you needed to scale by double clicking on the _lod_flat, write this number down.
LodtreesGuide3

  • Now open the _lod_flat.nif file in Nifskope, right click on the model in the render window, choose transform and edit. Change the scale to the same amount as you scaled in the CK, then press accept.
  • Right click again on the model and choose transform and apply.

LodtreesGuide4

Re-texture _lod_flat file
If you are only going to add new trees to your own worldspace you will need to re-texture the nif file to match your worldspacetreelod file. If you are using the new trees in the Tamriel worldspace, and only changed the original TamrielTreeLod.dds file you can skip this step.

  • Now re-texture the model to your WorldspaceTreeLod.dds.
    You find the treelod image where you put it under Skyrim/Data/Textures/Terrain/YourWorldspace/Trees.

LodtreesGuide5

UV-map

  • Most likely you will need to change the UV-mapping to fit properly. Right click on the model, choose Texture and Edit UV.

LodtreesGuide6

  • In the new window that opens you can see a box of white lines, within the lines are the image show on the model. Select the lines with the mouse or Ctrl A, now you can move it and scale it (Alt S) to fit your tree. In the render window you will see the changes you make.

LodtreesGuide7

  • Save the model as NewTree_lod_flat.nif
  • Put the this fil in the same folder as your tree. You don’t need to add this to the CK for tree lods to work.

But if you wish to check that the lod tree looks OK, you can add it as a static object. I suggest doing this in a test esp. Testing can be good so you see if you need to scale or change the UV-mapping more.
If you have made changes to the TamrielTreeLod.dds file you will need to change the UV-mapping of all the original skyrim _lod_flat trees as well, otherwise all lod trees in Tamriel will look weird.

Generating Tree lods in the CK
Only load the essential files in the CK.
*Remember which they are for later if you need to use Tes5Edit to fix the wall of tree bug.

  • To generate the tree LODs, go to World/World LOD.
  • Select your worldspace in the list, click Trees under Meshes, and then Generate.
    A new window will show the progress.

If all goes well the CK has generated a .lst and several .bbt files that you can find under Skyrim/Data/meshes/terrain/Yourworldspace/trees.

Fixing the Wall of trees bug with TES5Edit (only large worldspaces)
If your worldspace is larger that +/- 32 cells you will run in to the wall of trees bug. All the tree lods that are outside cell +/-32 will be shown on the border of cell +/-32. But don’t worry, TES5Edit can fix this for you.
Open TES5Edit
Load the same files that you had loaded in the CK when you made the tree lods*.
Right click on your file, select Apply Scrips, then choose the Skyrim – Tree Lod Files patcher in the menu, press OK. Select your Worldspace in the menu, and OK. Now the Wall of trees bug should be fixed.

/E

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