LOD Help or rendering large amount of trees

[cupsster]

Hi,

i would like to know some technique you are using when rendering large amount of trees in scene for example. Or where to find some tut on this. I'm doing area approx 9x9 km large and tere are closeups and flyover. Also a lot of moving people is required in scene so i need advice about some general technique to keep render times and ploycount reasonable...

 

Thanx for anny suggestions

 

what i'm looking for:

[Camby1298]

Depending on what software your using; you could fiddle around with Proxies for both Vray and Mental Ray (assuming your using max) Also for those examples check out the Groundwiz plug-in for max...Look at the galleries and tutorials that are included. They are very similar to what you are trying to acheive.

 

http://www.gugila.com/

[cupsster]

i'm using max^vray but i have problems with rendertimes. they are quite high and there is about 4 000 000 trees im trying to manage that with maped planes but without great succes.. any other advice?

 

i tried also vray proxy with groundwiz but cant archieve low poly on single tree.. i'm thinking that there is posibility to combine various proxy for different camera distance..

 

soon i can post some pictures...

[Devin Johnston]

Is this a rendering or animations, I've found that when using Vray and proxy's in an animation if you use the pre-pass method you wind up with much higher render times than if you just used the nth method.

[Dave Buchhofer]

theres no easy way off the shelf.. you may want to take a couple cues from how they manage this type of thing in games..

 

take a peek at a "3-tier" level of detail used for grass fading out into the distance and see if you can integrate something like that as your types of distant trees? http://meshula.net/wordpress/?p=119 http://www.antisphere.com/Research/Forest.php

 

its not directly applicable without using a little creativity, but its the sort of thing i tend to look towards for new ideas to try when running up against some of these issues

 

in the end, the best way for you to deal with the 'huge expanse of tree's problem, is to get creative with your shot selection, framing.. and planning it out so you know exactly which parts of the scene are going to need high detail tree's when..

[cupsster]

hello again, after all, i found solution with groundwiz plugin and vray proxy as distribution object.. distribution works vell but i cant slove vray proxy problem with instanced geometry.. when i add a proxy to scene and chceck test render for material it seems ok for that proxy but when i render distributed objects they have only a base color of wire of that proxy, no materials, no mapping.. shading technique in groundwiz plugin is set to custom shader [ to let vray proxys render themself ] but no succes.. see atached img.

 

trees3D - left proxy 2 on right original custom made geometry [source for proxy]

 

thnx

[FlyinHawaiian]

Don't know if you're done with this project or not, but for what it's worth, here's my two cents. If I were tasked with this, I'd make a full-res version, a slightly optimized version and a extremely optimized version and lastly a version consisting of a plane with a picture of the high res version mapped onto it. I'd run my camera animation and composition tests with the card version just to see general fill, etc. and then, I'd break the landscape up on a per-shot basis. Depending on the distance from the cam, I'd swap in the high res trees in the immediate fore (using a replace script or "clone and align"), then, the med trees, etc, etc, until you have 3 or 4 groups of trees of steadily lower level of detail. (This could probably be automated rather easily by someone who knows Maxscript - I'm guessing you could take a set distance from the camera and replace all cards from 0' through (x') with the high res ones, and so forth.)

 

Then, I'd render at least the cards and possibly the low trees group each into their own pass (because I guarantee the cards won't look exactly the same as the 3d with the same 3d lighting scheme since cards don't really pick up lighting much) and color correct them to match in post. For speed, you could even run the background tree cards in scanline.

 

Anyway, hope this helps or maybe triggers an even better idea in a sharper mind than mine.

 

Aloha,

Joel

 

oh, and ps, be sure to set the Dynamic memory limit under the VRay system panel to as high as your physical memory allows (assuming some spare mb's for your OS, etc.) as the default of 400mb starts to be too little after a few million polys. You'd be surprised how much this helps. I was just testing a scene with about 100 full 3d proxy trees and the times went from an hour to a minute. (You may want to test what the threshold is that puts your scene over the memory limit and break up your layers that way) Good luck!

[manta]

looks like you're using opacity maps for the trees...you would be better off using real geometry...

[cupsster]

Don't know if you're done with this project or not, but for what it's worth, here's my two cents. If I were tasked with this, I'd make a full-res version, a slightly optimized version and a extremely optimized version and lastly a version consisting of a plane with a picture of the high res version mapped onto it. I'd run my camera animation and composition tests with the card version just to see general fill, etc. and then, I'd break the landscape up on a per-shot basis. Depending on the distance from the cam, I'd swap in the high res trees in the immediate fore (using a replace script or "clone and align"), then, the med trees, etc, etc, until you have 3 or 4 groups of trees of steadily lower level of detail. (This could probably be automated rather easily by someone who knows Maxscript - I'm guessing you could take a set distance from the camera and replace all cards from 0' through (x') with the high res ones, and so forth.)

 

Then, I'd render at least the cards and possibly the low trees group each into their own pass (because I guarantee the cards won't look exactly the same as the 3d with the same 3d lighting scheme since cards don't really pick up lighting much) and color correct them to match in post. For speed, you could even run the background tree cards in scanline.

 

Anyway, hope this helps or maybe triggers an even better idea in a sharper mind than mine.

 

Aloha,

Joel

 

oh, and ps, be sure to set the Dynamic memory limit under the VRay system panel to as high as your physical memory allows (assuming some spare mb's for your OS, etc.) as the default of 400mb starts to be too little after a few million polys. You'd be surprised how much this helps. I was just testing a scene with about 100 full 3d proxy trees and the times went from an hour to a minute. (You may want to test what the threshold is that puts your scene over the memory limit and break up your layers that way) Good luck!

 

THNX

 

we're thinking paralel

 

exactly that i'm doing right now with googila plugin but i must avoid of using vray proxy in render shader rollout cause plugin always trying to pass all the trees in scene instead of only visible ones so i switched to standard shader with higher max object count so it pass to render only a nessesary trees with some treshold value in camera wiew. this method i'm trying to model 3 types of custom trees as you mentioned: MAX, MiD and low an use LOD rollout where i load this trees as LOD in case of one tree with switching based on BBox percentual count in diagonal of output image.. it should guarantee smooth transition from one object to another casuse mid-res vesrsions are optimizet from high one and min is billoard render of mid version

 

for now i need advice how much it should be for hi-poly count, cause in animation is aprox. 1 600 000 trees for which i like to have a shadow... on ground mainly.. [bake ??? : ) ]

 

lighting is static vraySun and terrain snow shader shader is only a normal map + color for now

 

trees on atachced images are only testing models by me. planning remodel them from scratch.. but there are 2 LOD on them

 

btw: how vray is handling opacity on such a large scale? isn't there a slowdown? i 3 times ended with error type of : need more slots >>> must try with Dynamic

[cupsster]

manta: some advantage of using geometry over alpha maps? i missed something? i understand basic billboarding but you seem to know something we don't

[FlyinHawaiian]

"manta: some advantage of using geometry over alpha maps? i missed something? i understand basic billboarding but you seem to know something we don't "

 

I would go over the chaos group forums and search the differences between opacity or geometry leaves multiplied by a million trees. Geometry is nearly always faster (especially if the geometry is semi-optimized). So, I would try to make the med res trees with goemetry too and render the opacity cards that you have for the furthest reaches rendering in a seperate pass than the rest of the trees. Render the opacity cards in max scanline render, without lighting and self-illuminated to 100. Then, comp them into the background and color correct them to match your med and high trees.

 

Of course, before doing any of this, try the whole scene with med proxies alone (no opacity leaves!) and with your dynamic memory cranked as high as possible (given your installed ram amount). You may just get lucky. Of course, your other problem might be flickering, but that's a little easier to overcome than simply getting millions of trees to render.

 

Good luck!