Vegetation has always been a neglected topic when it comes to tutorials. So I have decided to give the community exactly what they have been asking for. This method makes a tree with a reasonable number of faces. (mine came out to 7,128) This allows for having multiple trees without your scene becoming too heavy. Another great thing about this method, is that you can use it in the blender game engine. If you’re not using Blender, you should be able to use the same methods in whichever program you are using.
In this tutorial you will be learning
Modeling from details first
Creating normal Maps using xNormal
First load your reference photo into the background.
Press “Shift +A” and insert a tube into the scene.
Start maping the tube to fit the trunk, and main branch.
Select one segment from the main branch, and duplicate it “Shift + D”.
Use this new segment to shape out another branch.
Repeat this same step for all of the main branches.
Right now, the tree looks flat. This is no good.
To fix this, start pulling around verts along the Y axis.
Another thing you can do is to put the 3d cursor at the base of a branch, and rotate along the cursor.
Repeat these same steps for all the branches.
Now we need to connect all the main branches. to do this, delete the closest 2 faces where a branch intersects.
Now insert an edgeloop with “CTRL + R”.
Now merge the outer verts together, press “W” to open up the specials menu, and select Merge.
This looks too uniform, so pull the verts around a bit so it looks natural.
Repeat these steps for all the branches.
Now we need to make the smaller branches, so add another tube.
Start shaping out a branch.
Duplicate this branch, and place it to make a forks.
Now it’s time to UV unwrap the tree, so split the 3D view, and select the UV/Image Editor.
Now open your bark texture.
Make sure that the caps are deleted.
Select the edges where branches connect, as well as an edgeloop running down the branch, and mark seam by pressing “CTRL + E”
Now select all, hit “U” and select unwrap.
Change the Viewport Shading to Textured
Right now our UV’s are too small, so scale them up.
Some of the UV’s may be stretched, so edit them to make the bark texture a little more uniform
Repeat these last few steps for the small branch that we made.
Now on to the leaves. Load up a photo of a small leaf cluster into Gimp or Photoshop.
Crop and scale the leaf cluster into either 512X512, or 1024X1024
Mask out your leaves from the background.
With this mask you can easily make your color and alpha map.
These next new steps are optional, but making a normal map for your leaves will really help push this to the next level
In a new scene, Create a plane.
Split the view and open the UV/Image Editor.
Create a new material, turn on Z Transparency, and change the alpha value to 0.
Now apply your texture maps.
For your alpha map, uncheck Color. Check Alpha, and change the value to -1.
In the 3D view, change the display mode to GLSL, and change the Viewport Shading to Textured.
Add a Multires Modifier, and set the levels to 8.
Now go to Sculpt mode, and sculpt the plane to give the leaves some depth.
Duplicate your plane with “Shift + D” On one copy apply the modifier, on the other turn off the modifier.
Export both of your planes as .obj.
In Xnormal, import both your low poly plane, and your high poly plane.
In Baking Options, chose where you want to save your file to, then Hit the Generate Maps button.
Load up your bark texture into Gimp, or Photoshop, and desaturate it.
Apply a slight Gaussian Blur, Adjust the levels like so, Then Invert the image.
In Xnormal, click the “tools” tab, then “Hightmap to normal map”
Right Click in the Hightmap window, load your new bark texture. Then In the Normal map window, right click and select Generate.
Now right click, and save your normal map.
Now go back to your original scene file, and add a plane. Open your leaf color map into the UV/Texture Editor, and unwrap the plane.
Move the object center to the start of the twig.
With the face selected in edit mode, open the “specials” menue by hitting “W” then select “Subdivide”.
Move the verts around so this plane does not appear flat at any angle.
Add a new material to the plane. Enable z Transparency, and set the alpha value to 0.
Load your Color map to the UV coordinates.
Check the Specular Color box. This will make the specularity look much more realistic.
For your Alpha map, check the Premultiply button, as well as the alpha button, and setting it to -1.
For your Normal map, make sure to check the normal map button, and that you change the Normal Space to Tangent.
Repeat the same few steps for the Bark. (excluding the part on alphas)
Set the Shading Mode to GLSL.
To get a better view, of how the normal maps react, change the point light to a sun, and give it a slight angle.
To make the leaves double sided in the game engine, change the engine to “Game Engine”.
Now in Edit mode, select one face on the plane. In the Object Data Tab under Normals, check “Double Sided” In the same tab under Texture Face check “Two-side” as well as changing the transparency to Clip Alpha.
Duplicate the leaf cluster and position it onto the small branch.
Keep doing this as many times as you feel the need. Try to position them in such a way that gives good volume without the need for ridiculous amounts of leaves.
Now join all the leaves to the branch, and move the pivot point to the end of the branch.
Now place the branch onto the main branches of the tree, and duplicate until the tree is full. Then parent all the branches to the tree with “CTRL + P”.
Now put it in a scene, and you’re done! (This image is from the Blender Game Engine)