LC #42 Pipers Alley

View Full Version : How to attach lots of leaves to a tree?

05-21-2008, 10:46 AM
Hi there,

I need to model a detailed and photoreal tree (let's say an oak) for print resolution.

Creating the trunk and twigs will be pretty tedious but straight forward (i.e. zspheres in zbrush).

But I am looking for a comfortable and flexible way of plugging hundreds of leaves to the twigs so they are natural looking in regards of rotation and "gravity".

Might this be possible i.e. with some sort of geometry painting or fur or particles?

Do you guys have any idea?
tom 8)

05-21-2008, 11:59 AM
Paint FX is pefectly suited for what you are after, typical of Maya it could be a program on its own. Its incredibly flexible and vast, when your done modeling you can convert it to polygons and turn the leaves into nCLoth allowing for some pretty cool FX.

If you are looking for tutorials:
Gnomon Paint FX is great, you may also find the Digital Tutors tutorials helpful for a general breakdown of the different attributes.

05-21-2008, 01:13 PM
This oak looks pretty nice for $10:

Though I haven't seen the geometry, I'd pay that just on the off chance it worked.

05-21-2008, 01:29 PM
Hey thanks for replying.

I am already playing around with PaintFX but since the tree will be portrayed very close to the camera and in a very high resolution, I'd prefer real geometry for the leaves instead of transparency mapped planes.

Maybe I can find a way to automatically replace the square leaves created by paintFX with my custom geometry which also inherits the orientation of the paintFX squares.

hmmm ...

05-21-2008, 05:26 PM
Note that you can edit the leaf attributes for pfx to have the leaves shaped, as opposed to tranparency mapped planes. Make sure that the brushType is mesh. Key attributes to play with are:

If you want a hard fold in the leaf center it is a bit more tricky but one could potentially apply a displacement or bump to the leafshader after convertiing pfx to poly.


05-23-2008, 10:47 AM
Hey thanks for the tip, Duncan! Didn't realize that there are THAT many tweaking options for PaintFX! Seems like my problem is solved!

05-23-2008, 01:03 PM
Yeah, I'll chime in with the others about paint fx too. Its great for photorealisitic foliage.

However, Duncan, I remember you mentioning in a thread in these forums to stick to the preset oak tree brush in the visor as editing the seed or creation attibutes could yield unwieldy results.

I have actually faced this problem before in an oak tree brush that I tried editing, where the main trunk of a pfx tree didn't branch out neatly into two or more branches. Instead, there was an undesirable mesh intersection where the branching happened and that didn't look great for closeups (of course, we could always cheat it by choosing to hide the intersecting mesh). It was as if two separate branch meshes were just stuck onto the main trunk mesh.

In fact the default oak tree brush too has this very problem.

Any particular reason why this could be happening? I wish I had the file with me right now to put up some screenshots.


05-23-2008, 05:03 PM
The oak brushes use the branchAfterTwigs setting, and it could be that the twigAngle1 is a bit too high to blend with the trunk. You could try lowering twigAngle1 and then lowering twigStiffness (or increasing gravity) to pull the branches back down.

However one will not get a good fillet of angles where objects meet. One could convert the pfx model to poly and then clean up joins, delete undesired branches etc. on the poly model, but this will of course take time to do and also make it harder to modify or animate.

You might also try turning off "branchAfterTwigs", but this will change the character of the tree a lot and require more editing. Note also that for growth animation branchAfterTwigs has some bugs.

Note that you might try convert pfx to nurbs on simple tree models( will be too slow on complex ones ). The resulting surfaces will attempt to be tangent at branch points( although not at twig junctions ).


05-23-2008, 07:11 PM
Ok, thanks Duncan. I'll make a note of that the next time I use a similar brush. Is this a problem with other implementations of l-systems as well (can pfx be called one though)?
And are there any major overhauls planned for the maya pfx module in the near future?
Throbberwocky, I just remembered having downloaded a maya script from highend3d to make tree trunks sometime ago. Though I never got around to trying it, it apparently creates a polygon tree trunk with branches depending on the curve you create (or something like that). Will dig it up tomorrow. Also, if you're going the pfx to polygon way, remember NOT to delete its history to retain the pfx animation and dynamics.

05-23-2008, 11:44 PM
The blending is not a problem with either paint effects or l-systems in particular( which are both different techniques ). It is just a question of implementing joins with fillets instead of simple tube intersections. High quality joins are both calculation intensive and more work for the developer.

With regards to future pfx development I can't discuss future Maya development plans.


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