Tree creation using particle generator

Software used:
-3ds max
-Photoshop

Things I assume you know how to do:

-UV Unwrap a basic model

-Basic (beginner) 3ds max knowledge (nothing fancy, but you should know how to apply a texture to something, know where the material editor is, know what sub objects are etc.)

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1) To begin with, we must have a fully fleshed out trunk. This can be done through standard box-modeling techniques, or through the technique outlined in my other tree-modeling tutorial. I will make one the way I have previously discussed because it is fast and simple.

2) Once the solid geometry trunk is done, add your secondary branch planes.

3) Now, since the particle system will generate leaf cluster placement based on polygonal density, we want to make sure that the 2D planes have similar polygon density to the trunk itself, so that an equal density of leaves will be placed on the upper thinner branches as the trunk area itself. We can further manipulate the leaf placement with this in mind later on, but first we need to have the polygons in place.

4) Since we don't want a wasteful amount of polys in the upper branches for our final, in-game model, we will make a clone of this cluster of planes for the sole purpose of propagating foliage, then we will throw away the subdivided planes after we have the leaves generated.

5) Next create a particle array and a plane (propped upright with it's Xform reset.)

6) Set the Particle Array settings as shown. Changes to the total number of particles, the speed, variation and divergence, size and variation should be set as desired, but start with what you see here, and when you fully understand the results, you can experiment.

Particle Quantity should be set to "Use Total" so that you can control exactly how many particles/polys are being generated.

Under Instancing Parameters pick object and you will want to pick a one poly plane that you have created with your leaf texture on it.

7) Select your trunk, and in poly mode, select the polygons that will make sense to have leaves sprouting from. As you see in the screenshot, you will want to de-select the polys that exist too low on the trunk or near the core of the tree.

8) Scale the frame slider to 20 or so and you will see your planes sprout all over the tree. Adjust the selected sub-objects as needed, and when you have the planes floating the way you like them, create a "Mesher" and choose the particle system.

9) Then, nudge it until it is overlapping the PArray planes perfectly, and then "Convert to Editable Poly." Now you can delete the PArray and the plane.

10) Clone / Rotate 90 degrees so that every plane has another plane bisecting it on it's pivot (center) - now every plane should be a paired cross of planes.

11) Select your Mesher, and run the Soulburn script "object Detacher" (or any such script that breaks an object into pieces based on it's elements)

12) Now that you have a few hundred individual planes, you want to attach them in 1/4ths (if you have 200 planes, you want to attach 50 of them randomly, until you have 4 objects each comprised of 50 randomly selected planes.)

13) Use the Soulburn script "Selection Randomizer" to choose the 1/4 randomly. Once they are selected, hide unselected, and attach all of these into one object. Unwrap UVW and scale back the square UV projection into the upper-left quad of the 0-1 space:

14) You will repeat this process for the remaining 3/4 of the planes, and when all 4 selections have been sequestered, attached respectively, and unwrapped into it's own quadrant of the 0-1 space, attach all of them into one object. The 0-1 space should look like this now:

15) Make a texture page 2x2 style like the type described and illustrated in the other tree tutorial:

Example:

Applying it to this mesh, you should have a full canopy of foliage, and since the textures are randomized, the "Rorschach" effect should be well avoided. Rorschach example:

16) Now you can go in and move individual crosses (delete / move the foliage pieces in crossed pairs so that no single planes are floating in there) to taste. If you see a bare spot clone a pair from another part of the tree and drag it over. If the tree is too sparse, go into element mode, select all, and scale up 20% (or more.)

17) Once the mesh is done and you are happy with the look of the canopy, remove the subdivided, high poly branch planes and replace it with the original single card branch planes. If you used a subdivided trunk then replace that too. Your tree should look nice and random, and the foliage, being generated based on the trunk and branch geometry should retain the look and feel of the tree.

Finally, now that you have familiarized yourself with the process, consider that since the process generates foliage based on the geometry of the trunk, why not save yourself some time and do the entire forest at once instead of tree by tree? Create your generator by cloning your tree trunks whenever you have them all placed, and attaching them all into one object. Then, follow the above steps, but for the total number of particles, multiply whatever you would use for a single tree by the number of trees you are generating. In the example below I am doing 9 trees at once, so I entered 900 particles rather than the usual 100. This is a great way to do large amounts of trees because since it is particle based, they each have their own unique, random feel to them.

Scroll the slider and see the trees all grow at once:

Finished grove of 9 trees simultaneously:

Enjoy,

-Andy Zibits :)