A Cartoon Forest

I've tried to make a 3D forest a few times, but I've generally been really disapointed with the outcome. (you can see my castle animation for an example.)

I came up with a solution, however, that seems to provide a reasonably consistent quality.

Note that most of my rendering is meant to look like hand-drawn animation. These trees look pretty good for stylized work, or as animation, but won't fool anyone for photorealistic work.

Start with a low-polygon tree. I created a tall, thin box with six segments. I scaled the modeler until the grid was 500mm. This means the box is about 3 meters tall (~= 10 feet), and half a meter thick (~= 18 inches).

Use the drag tool (ctrl-t) to give the tree a twisty, bendy look. Taper it a bit at the top. Make sure you do this from the front and from the side.

Pull out a branch around the bend in the trunk. Select one of the four-sided polygons just above a major bend. Smooth Shift (Shift-F) and click on one of the modeler windows. This creates some geometry that you can't see yet. Move (shift-T) the polygon away from the trunk. Smooth shift, click, and Move the polygon again. Use the drag tool to move adjust the thickness of the branch.

Pull out a few more branches to make the trunk interesting. You don't want to make a lot of trees, so you should make this tree look different from different directions. It shouldn't take much effort to make an interesting tree.

Now it's time to make the canopy. Use the ball tool (shift-O) to create a ball that covers all the tops of the branches you made. You will have to go into the numeric properties (n), and select tesselation. A tesellated ball looks a lot better.

Select the magnet tool (:) and drag the ball around. You will need to use the right mouse button to adjust the size of the magnet's influence. Use the left mouse button to drag the geometry around. Try to organize lobes of camopy around branches.

Make sure you have the layer with your canopy active, and create a new surface (you should not have any polygons selected, type "q" to create a surface). Select a shade of green. Next, switch to the layer with your trunk, and create a surface (q), make it brown.

Next, bring the canopy over to the same layer as your tree. You can do this by copying (x) the layer with your canopy, and then pasting (v) onto the layer with the trunk.

The rest of this exercise, really, is to create good surfaces for your object. Open the surface editor, and select your canopy. Give it a dark green color (024 037 014) as the base color. click on the "T" icon to open up the textures screen. Use the drop-down list labeled "Add Layer" and select "Procedural". Select a Procedural Type that gives you a nice random cloudy texture. I picked Coriolis, but turbulence should give you a good choice, too. Set the scale to 1 m in x, y, and z. Check World Coordinates. Set the color to a light green (047 218 037). Click "Use Texture" at the bottom.

To give your tree a "leafier" feel, you also want to adjust the transparency. Set the transparency to 100% and then click "T" to create a texture on the transparency channel. Add a Layer, and make it a gradient layer. Set the Input Parameter to Incidence Angle. Set the value of the first key to 100%, Alpha 100%, Parameter 0.0. Create two more keys, one with a parameter of 45.0 and another with a parameter of 60.0. The first should have a value of 100% and an alpha of 100%. The second should have a value of 0.0% and an alpha of 100%. The purpose of this layer is to keep the center of your tree looking solid. The thickest part of the tree shouldn't have any holes where you can see through the canopy. We only want that to be on the sides, and this gradient will fix that.

Next create another layer, and make it procedural. You want a blobby procedure, and "Crust" fits the bill. Select "Crust" from the procedural Type drop-down list. The default values should be okay, but check "World Coordinates" and set the scale to 200 mm in each dimension. click "Use Texture".

Make sure "Smoothing" is selected, and set the smoothing angle to 180

The trunk is a lot less important, but needs a quick fix. Select the trunk surface in the surface editor. Make sure "smoothing" is checked, and adjust the smoothing angle to 180.

That should complete your tree. You'll probably want to save a version of your model, now, and save all successive changes to another model file called Forest. Now to make a forest. Your object layers should all be empty except for the one with your tree. Select an empty layer. Use the zoom tool to zoom out until your grid is 50 m.

Select the Spray Points tool in the create menu. Spray a nice random mess of points all over the x-z plane until you have a density that you think is appropriate for your forest.

The spray tool makes a big mess in 3 dimensions. With no points selected, set values (ctrl-V), and make the y-coordinate 0. Next merge points (m) on the Construct menu. Select "Fixed" in the Range, and change the distance to 3 m. This is the minimum space between trees in your forest. this should give you a flat plane of points which are randomly distributed, but at least 3 meters apart.

Now, activate the layer with your tree in it, and set the layer with your points as a background layer (click on the lower half of the layer icon). Under the Multiply menu, click "Point-Cone-Plus+". In the dialog box that pops up, select -180 for Min H under Random Rotation. Enter 180 for Max H under Random Rotation. Under Random Size, use 0.8 for Min and 1.2 for Max. In the bottom section of the screen, select the Y Axis "+" option, instead of the center. Click OK. If you don't have a lot of ram, watch your computer crash. If you do have enough ram, wait a bit, and then save your forest model.

From here, the tutorial is more-or-less over. You can open layout and add your model, and render it to see the final output. I used enhance High Anti- aliasing, and skytracer with its default settings. I also set volumetrics options and put some fog to hide the small number of trees I put in this rendering.