A simple three layer Treewall SObject using one diffuse texture and alpha transparency "shadow" texture in front of it. Two versions, one for close by treewall, one for far-way distance.
Usage: place the treewall using "Follow Spline". When placed, switch to "Vertices Follow the Ground" to make the shadow follow terrain shape. Adjust height (or add nodes) to fine tune the shadow mesh.
Texture replacement: take any type of vertically tiled texture. use Chroma for main texture transparency. Make a copy from the main texture and copy it to alpha channel on black 256x256 texture (modify levels and use gaussian blur with 1.0 at least). The shadow texture is aligned with the first treewall layer, second and third are in offset and scaled to create more variation..
- Shadow mesh can not follow very radical terrain shapes, you can try adding a node to the bugging place or stretch out start/end nodes a bit.
- DO NOT USE THIS AS COLLISION OBJECT! In fact, do not use any SObject for collisions but this kind of three layered+horizontal shadow mesh is particularly nasty. Use "no render" walls instead.
TIP: You can use only the textures to create similar shapes with Wall tool for more detailed control and more coherent mesh.