Posted: Apr 13, 2010
Published by: the area
Homepage: Visit the page
Software: Autodesk 3ds Max
Category: Modeling, Shaders
Creating dense, attractive, low-poly (200-300 triangles) trees without the "card" look.
-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.)
I see this ugly technique in games that sell, as well as in first year CG students' projects.
This is not a defined, "set in stone" kind of thing - you may find a better "basic unit" for a Sugar Maple, or, you may choose to use more, smaller units for a higher poly tree, but there is usually a recognizable pattern in a tree and once you find it, you are creating the tree in the most efficient way possible.
This allows you to be conservative with your branches as well as the amount of polygonal definition you give them.
I start with the leaves because this is the part that really defines the look of the tree. It is the most important, and while most people think it is the easier part, you will soon learn that it isn't, especially once you read my trunk tutorial below.
This will be an autumn tree, but we can easily make the tree green after we are done, I'll show you how at the end of the tutorial.
3) Once this is done, copy this leaf and paste it onto a larger canvas. You want to make an arrangement of these leaves, creating the kind of "basic unit" cluster I described above. The best way to do this is to make a few different smaller clusters, with different sizes and varied orientations of leaves.
4) Once you are satisfied, link all of the layers above the background, and select the "Merge Linked" option.
5) Now, CTRL-Click the single layer you have now, and you will have a new selection based on all the leaves you have on that layer:
6) Click the "Channels" tab, and create a new channel.
7) "Fill" the selection with white.
8) "Select All" and copy this black and white image, then create a "New Document, and "Paste" it. "Save As..." and name it leaves_opacity or something indicating that it is the opacity map version of your leaves.
This is just a little insurance, so that if your Alpha channel is a hair off anywhere or if you resize the texture and the alpha channel is no longer a perfect match, you won't have a white halo around your leaves.
Create a 1:1 plane and apply the texture to it. Your leaves should be properly opacity masked as such:
11) Go into Top View and, selecting "Adjust Pivot Only", move the pivot out to the edge of the plane, to the appropriate edge where the leaves would be growing from.
12) Clone this plane until you have about 20 or 30 planes all perfectly overlapped.
13) Take this stack and Clone the whole stack, dragging them off to the side. You now have a backup stack for later, which is a good thing to have in this process, because the method we will use to distribute these leaves is not "undoable".
14) Create two more clones of the original pile, each one 33% smaller than the last.
15) Now we will use a terrific tool called Randerizer, by Matt Rapelje. This is a great tool for randomly distributing objects such as trash, rocks, bullet casings, etc. which would normally require a person to work rather hard at creating a randomly scattered look (this is harder than it sounds)
*Other types of trees and bushes may require similar settings but with your "basic units" upright instead of laying flat. An example of this is the Poplar, which is a rather erect tree with branches growing up, against gravity.
17) Go into Top View and move the mid sized one over to the large one.
*Some species of trees may require the reverse taper, thinning at the lower levels.
19) Now, go into your "Select by Name" view and grab about every third of the planes in the list. Now delete them. This creates random empty areas in your cluster that exist naturally in trees, which the Randerizer doesn't really create.
20) Manually prune any planes that stand out to your eye as "breaking character" - i.e. - making it apparent that this is not a real tree. Rotate the cluster and view it from different angles and prune until it looks OK from all around. Don't overdo it.
Before you begin, you will want to have the bark texture ready. Find a nice, large, evenly lit (as with the leaf image you started with) image of the bark, and open it up in Photoshop. Crop it square, and apply the "Offset" filter to it so that you can make it tileable:
Rubber stamp and cut/paste/feather until the seams are no longer visible. Now hit "Offset" again and you should see no seams at all. This means you did it right, and that the image is completely tileable.
Now, onto the trunk.
2) Select the center fine, your trunk, and expand the Rendering dialog in the Modifier column. Check the "Renderable," and "Display Render Mesh" boxes, and set the thickness to an appropriate value so the trunk looks right for your particular tree. For the main trunk you will want to set a slightly higher value for the "Sides" and, under interpolation, "Steps" (keep Optimize checked")
3) Select these 3 renderable lines and "Convert to Editable Poly". Now, you can attach them to each other so you have one object.
4) Now rotate it upright 90 degrees, and clone it. Rotate the clone 90 degrees the other direction, and delete the second trunk, leaving the new set of branches. Line them up with the original trunk:
5) Trim off some of the segments so that the tree doesn't look so uniform, and remove all the the endcaps of the tubes (they will not be visible from the ground and it will save you a lot of polys)
6) Under the Modifiers tab, select "Unwrap UVW". Hit the "Edit..." button, and under Mapping, select "Flatten Mapping..." The default 45 degree setting should be fine. Apply the bark texture to the model.
7) Rotate the UVs and flip any that need to be flipped so that the top parts are at the top and the bottom parts are at the bottom. This should be obvious because the bottom part should be wider. Then scale them large enough until the bark on your tree in the viewport look appropriate. See below:
8) Now unhide the leaves and stick the trunk under them.
That's it. I am including a link to the Randerizer script for anyone who wants it, and a special thanks to Matt Rapelje for making such a useful script.
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