ah, maybe it only results in negative space if they are intersecting.
what are they eyes? vertex colour? lamps? they seem to have a definite shape. Cool project BTW. Be great to see that flying above (through) your forest.
The eyes are just squashed spheres with a emissive material and then I stuck a red lamp in the head. The nice thing is it’s fully animation friendly.
On the tree front, I finished a cut of the tree I wanted to duplicate and attached it, but ran into a major snag. When I use a particle system to place trees on a hillside, I can’t emit particles from the tree. You can’t emit particles from particles I guess. So I went ahead and made copies of all the trees and emitted particles from them, but then the point density texture requires an object and since I had 50 trees copied every where I had 50 objects and I then needed 50 point density textures, but there aren’t enough texture slots to do it. I’ve come to the conclusion that the only way to do a hillside of trees and emit particles from the branches is to make all of the trees one huge object. It’s amazing how you can work an entire night and then go oh, woops should have done it that way… oh well.
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You cant birth child patrticles at end of branches? Oh well, cool tho.
NRK, nice job with the trees. Wouldn’t instancing, like Vue uses, be more efficient than particles for distributing trees? I am new to Blender so I don’t even know if Blender has a way to create billions of instances like Vue. In Vue the render times for trees is quite fast. Wish I could say the same for rendering clouds.
I would definitely use dupliverts.
Also, your forest might look more convincing if there was less space between the trees. Look at this photo, for example:
It’s more carpeted.
Thanks for the input. I tried dupliverts, talk about a feature with weird implementation in 2.49 and totally confusing in 2.5 (I don’t mean that in a harsh way, it may be great in 2.5 but without any 2.5 docs I haven’t figured out the nuances yet). I didn’t know dupliverts were so memory efficient compared to particles, I will definitely use them more, but I can’t use them here because particles only emit from one dupliverted object (per my tests anyway). And blender crashed on trying to render that to show you here(I think 2.5 is still to alpha to servive particle emitting dupliverts in render) I love your picture above. I think my next try will be to try muliple particle systems and point density textures. Until then thanks for the input.
Definitely onto something interesting here, I’m seeing a way to make human brains though. Very original thinking !!
Keep in mind you can make dupli objects real. Then particles would emit from all of them.
SO why not create a Forrest that has no spaces and delete what cant be seen, then it saves render time but gives the illusion of a lush thick bushy hill…??I like it.
That actually does look good. Its definitely good enough for tree topping hills or mountains a small distance away.
Ok, so I spent a lot of time playing with this tonight and I figured out that the best way to make trees is to emit particles from vertices of the hillside and then apply the point densit texture. I do not understand why there is no texture effector named transmission color. That is the main color variable for the material and it seems you cannot effect that value directly with a texture (or they named it something else and I missed it) I wanted to apply two sets of points to create multiple types of trees, but without the above option nor the ability to combine volumes I’m sunk. When you put two volumes in the same space there are all kinds of bugs and issues so I’m backing off for now until the technology gets a little more refined.
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I have tried to create a large forest using particles but I have come to the conclusion that if I want to achieve any type of realism I must abandon the idea of trying to make the actual trees out of particles. 
Using particles may work for very distant forests but in my tests I have found that if I want the camera to come anywhere near the trees they lose all realism fast so I don’t think particles is the way to go.
The only way I think I can achieve realistic trees in Blender will be to use an actual tree model and some sort of method to distribute them, whether that be “Particles, Duplicating, Instancing, Dupliverts or a Python Script” or some other method."
NRK, just curious, have you tried to import an actual tree model and distribute it using particles or some other method? This is the method I would like to pursue but I am still trying to figure out the best way to go about it. I have created many forests in Vue and the realism is phenomenal down to every last leave. Billions of trees can be rendered realistically. I put together this simple scene this morning just as an example of the realism I’d like to get in Blender. I DO wish there were some way to achieve this in Blender.
You can fly over the trees or down into them and they still look real. The rendering time is not bad either.
Maybe someone with some knowledge of programming in Blender may know which method would be the best to distribute a tree model millions/billions of times. (Particles, Duplicating, Instancing, Dupliverts or a Python Script of some sort)
pg
Tried mapping other textures here is blend and image. used build 27115
Sorry but I couldnt spend much time on it, I think that you could get really good results. I cant seem to get the colour to remap to a blend either like others have with flames in smoke, but that is directional. We really need spotty changes I guess, thats why I over layed a cloud texture, but didnt fiddle with mapping much. The reds are to show the variation clearly.
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tree colour variance.blend (545 KB)
Paint Guy, I agree Vue is incredible and I have seen it’s results. If I wanted an image like the one you posted I would use dupliverts. They are by far the most memory efficient things in blender. I have dupliverted up to 75 million vertices without problems(and could have gone higher), although you can’t render them efficiently in 2.49, you need to go to an efficient renderer like luxrender. 2.5 has major upgrades to the octree via GSOC so it should do better rendering massive amounts of dupliverts. I wouldn’t use particles because they slog down much quicker due to the overhead of their cache and extra bells and whistles that slow them down.(you may get away with particle instancing each tree, but I wouldn’t want to try 75 million particles) As to your question, I did import a tree model, the one posted above, but had to use particles for the leaves and couldn’t get particles to emit from the dupliverted or particle instanced trees. The standard way of doing trees is to model every leaf, but if I want to do LOTS of them I should be able to fake them with volumes (even with your picture above since I don’t see any individual leaves in it), but so far I have been stymied by two issues: I can’t effectively change the color of the volume, and I can’t do two volumes(without bugs).
3PointEdit Dying to check out your .blend since I do see different colors, I had to do it with reflection color before, but it somehow felt wrong to me since it isn’t “real”, I will write more once I get to a computer I can check out your file with thanks for posting it.
Thank you both so much for helping, I really appreciate the actions you both have taken, if anyone is interested in my .blend files, let me know and I’ll post them.
Thanks NRK. If you have dupliverted up to 75 million vertices then I may try this method after I finish the project I’m on. In the mean time I look forward to seeing what you come up with. 
pg
Well here are some trees in a snowy vista, but I cant figure a way to get snow caps on trees. Ideally I would like snow to start at a uniform distance from the ground, rather than at a global height in the image. As the trees vary in topological height themselves.
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snow trees.blend (742 KB)
Well I just went out and fertilised the trees, and now they’re bigger!:eyebrowlift:
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Cool, I like the first one the best. Looks like a pastel painting
pg
An earlier version had some other texture subtracted from the trees (volume) to simulate leaves. That would stop them looking like little houses I suppose.