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TUTORIAL6 I've created that scene to demonstrate how to make a nice looking tree without using all those new rendertime-consuming solutions like GI or SSS. That scene renders about 1 minute per frame (PAL) and contains fairly complicated geometry (tree). |
| A tree created using TreesDesigner + LeavesGenerator comes with many ready-to-use UV maps and weight maps. I'll show how to use them to fake shadows and lighting and to make tree looking better and more natural. | |
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When you look at a real tree it looks 3D, isn't it? But try to look at
it with one eye closed. It is big difference! It is no longer 3D and in
most cases it looks just average all its beauty is gone - this is why it
is so difficult to make a good photo of a tree or to create one in 3D software.
Even perfect model may look poor without detailed lighting and texturing. Let's take a closer look to a real tree. When you look at it in a cloudy day, you can notice that leaves inside a tree are darker than those outside. Yea I know it is a basic thing :-) but it is important to remember that when you creating a tree in 3D. The same effect exist in sunny days but it is not that obvious because of strong sun shadows. You can turn on GI and wait.. wait.. wait... and wait a bit more and finally get a render that will still be poor (especially in LW). A tree geometry is very complicated and you will need a great deal of rays to get nice, smooth look. Here is good time to try using one of weightmaps or UV maps that was created by LeavesGenerator. I'll show two methods, you can choose whichever you like more. |
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LeavesGenerator always copy weightmaps from polys on which
leaves were created. Each leaf have all weightmaps from the source poly
with value from the position on that poly. It might be quite useful when
you animate a tree using weightmaps (leaves will stick to branches) but
it might be also useful for texturing. TreesDesigner creates two weightmaps
for branches: one based on branch thickness and the other one based on
distance from branch tip. Both weightmaps are copied to leaves and for
the texturing purpose the second one will be pretty handy. As you can
see on the picture this weightmap fits perfectly my description of tree
in a cloudy day - leaves outside a tree have different weightmap value
that those inside. Applying simple gradient to diffuse channel we get
nice faked soft shadows on leaves inside a tree!
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This solution is simple but unfortunately LW renders gradients on weightmaps a bit slow. There is another simple solution that allows to make leaves inside a tree darker (there are more but requires either 3rd party plugin or null usage). Leaves generator creates special UV map called 'LG_all_leaves'. This map contains all leaves side by side and its primary application was to easily vary leaves colors. During leaves creation user can choose if this UV map should be sorted. The sorted UV map will have outside leaves on one side, inside on the other so it fits the needs perfectly again :-). With simple bitmap gradient applied to diffuse channel with that UV the effect will be similar to the previous one and should render faster. |
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| When we look at trees and especially leaves we can notice that they are a bit shiny and reflective. The good idea to use the same weightmap or UV on reflection channel and add HDRI map as a reflection map - just a little bit, like 1-2%. Again leaves outside a tree will get more reflections (internal leaves reflect only other green leaves so their color don't change in reality). Combining it with slope angle gradient may produce even more realistic effect. | |
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| And last but not least important leaf feature is that it is
translucent. Using LW translucency gives acceptable results, however adding
a bit of luminocity (with the same gradient as above :-)) will help a lot
in some scenes.
Because tree's branches also have weightmaps and UV map ready to use it is easy to make similar ambient effect on them using the same method. |
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 And here is animation (1MB Dixv) |
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| Lighting the scene: In order to get nice dark shadow under a tree I used point light with limited range and -50% (minus). The same trick I used to get the darker area near rubbish bins. Few different spot lights with blurred shadowmaps gave nice ambient lighting (LW ambient was of course set to 0). To get final touch I placed one spotlight with slightly yellow-orange color to simulate weak sunlight. I also added projection image to that light to fake some additional shadows from non-existing objects outside camera view. |
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| Thats all folks :-) | |