ET17 Midterm: SpeedTree Tutorial

Creating trees from scratch on 3D programs can be difficult, often times resulting in botched attempts at trees courtesy from the uncanny valley. The program- SpeedTree aids in creating the accurate models and randomized details that modelers constantly aim for. In this tutorial, I will teach how to create a simple tree which can be put into UDK with full collision and mild wind interaction/disturbance.

When opening SpeedTree, you will be greeted with this screen.

As it is now, there is no project to work on, hence no options to add your assets. To open a new file, go to File > New which will lead you to your general workspace.

The blue window in the middle is your main viewer, where you'll see your tree constructed and its overall look. The text on the top left of the window dictates the polygon count and other miscellaneous information. The lamp on the top right shows where light is hitting the object which is an important factor to consider when making your tree.

The window above is on the top right of your workspace, where you can add your materials and textures, such as your leaves and bark to the model. There is also a Meshes tab if you needed to add any to your tree. This window is known as Assets.

This long window to the left on your workspace is your object properties. Each section on the spreadsheet controls different aspects of the objects placed for your tree. Factors such as number of notches, flares, size, optimization, starting angle, etc can be adjusted here. This is also where you will apply your materials to the objects on the main viewer.

This window is located on the bottom right and is where you will be adding all the features of your tree. From the roots, trunk, branches, and leaves; all assets are recorded here similar to layers on Photoshop. This what's called the Generation window. 

Once you've familiarized yourself with the workspace, you can get started on creating your model. Go to the Generation window and right click the tree icon > Add to selected > Trunks > Standard, to add your trunk.

Your main viewer should look like this, with the bare, featureless trunk on the center. Your Generation window should also have a new icon that says trunk.

Before going ahead and adding your branches and leaves, now is a good time to place a wood texture, since placing it now would make the branches come with the wood texture as well. Go to the Assets window,  and click the "+" sign next to the bar that says No Materials. From here you can add your textures and leaves if needed. I already have a texture for this tutorial so I'm selecting that.

Now that we have our wood texture, we can add it to our trunk. Go to the Object Properties window and find the section that says "Materials", open the tabs and from material, select your texture as shown below. Then your trunk will have the wood material placed.

Now that our trunk is textured, we can start adding the branches. With a process the same as the trunk, right click the trunk icon on the Generation window > Add to selected > Branches > Level 1 Standard. Notice how there are actually many other options for branch patterns, you can try to experiment with these to create different trees (pine, palm, oak, etc).

It looks very lovely, but to give it some more realistic detail, add some secondary branches on the branches you just added to simulate the smaller twig-like flanges most trees have. On the Generation window, right click the "Level 1" icon and repeat the same process.

Now it is time to add the leaves. Go to the Generation window, right click the icon the very top, which should say either "Level 1" or "Level 2" > Add > Leaves > Standard. The geometry for the leaves is always gonna be set to cards and will, at first, turn out as seen below.

The leaves that were just added look like that because there is no material for them to use. So go the Assets window and repeat what was done for the wood texture. It is important to note that the leaf image you use has to have no background, otherwise you will end up with the same geometry for leaves.

  
Now that there's material for the cards to use, go to the Object Properties window and find the section named "Leaves", then from material, select the leaf image. Doing so will replace all blank cards with the image of the leaf just added.

Now the tree looks complete, but instead we're gonna take a few extra steps to make it easier to work with in UDK. The tree, as it is right now, is made up of many polygons and might cause some frame loss if put into UDK. To reduce that, first toggle the leaves by clicking the leaf icon on top of the main viewer.

Then proceed to press 'W' on the keyboard to activate wireframe. This mode shows the actual geometry  that's on the trunk and branches. The more complicated the lines are, the more it takes to process it on UDK.

Now that we can see the wireframe, take a look at the Object properties window and look for a "Segments" section, inside which there is Optimization. By tweaking that, you can control how complex or simple you want your geometry. Notice in the picture below that there are less lines that make up the model, this makes it easier for UDK to process.

Press 'W' again to turn off wireframe and toggle back on the leaves for our next step. Even though our tree is structurally complete and made simpler for UDK, it has no collision and if exported as it is now, it will be an object that can be clipped through. SpeedTree has a simple way of fixing that by going to Tool > Generate collision primitives... Doing this will make the tree an object that can be collided with. SpeedTree calculates the general geometry of the tree and generates the area where collision will occur. You can toggle the collision objects by clicking the icon on the main viewer.

Two more things to be mindful of now that our tree is suited up and ready to go. The first is that you can toggle wind or breeze effects so the branches and leaves can move as if in a breeze. It's a pretty spectacular thing SpeedTree can do to add to a sense of realism. But keep in mind that if the wind effect is left on and imported into UDK, the tree will remain moving regardless of the environment it's in. The strength and direction of the breeze can be changed in the Object properties window.

The last thing is to know how to use the forces SpeedTree provides. Right click the main viewer and add any force. These forces distort your tree and cause some nice effects, if that's what you're going for.  The strength and placement of these forces can be altered through the Object properties window. The force I'm using below is the magnet, which attracts the trunk and branches towards it.

And that should be about it for making a simple tree in SpeedTree. Save your model and put it through the compiler and import it to UDK and enjoy your tree.

-John Vinuya
ET17 Midterm