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Author Topic: Best Workflow for very large scene with Forest!  (Read 822 times)


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Best Workflow for very large scene with Forest!
« on: March 09, 2016, 04:08:36 PM »

I'am dealing wiht a very large scene-setup here.  :o
I have to setup a scene like shown in the attached image.
Is there a recommended workflow to the scene handling? Proxies, Lod etc?

My workstation is a i7 2600k with 4,4ghz, 32bg ram and a gtx 780ti

thanks in advance

Paul Roberts

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Re: Best Workflow for very large scene with Forest!
« Reply #1 on: March 10, 2016, 06:33:52 PM »
Hi Phil,

Below are a few tips for creating large scenes with Forest Pack and links to further information where appropriate. In addition, you might find some interesting conversations and get helpful feedback on the V-Ray forums (assuming this is the engine you are using), for example you can find an interesting thread about optimising trees here.

Here are some tips:

- Use Forest LOD to simplify the materials on trees far from the camera. You could also simplify the geometry too but materials are often where significant render time savings can be gained. See the Forest LOD tutorial and documentation for more information
- To keep you scenes file sizes small , I'd import high poly objects like trees as XRefs. Set them to Display as Box to minimise viewport slowdown.
- Alternatively you can convert the trees to proxy objects, personally I'd only do this if I was scattering a lot of different types of tree or if they're animated but it's often best to try out both approaches to see what works best for your individual situation. You can see a list of the pros and cons of using proxies here.
- To cover large areas of grass, make  clumps that cover a larger area. There's a balance to be found between the size of the clump, its polycount, and the number of clumps you'd need to scatter to cover the area. In addition if your terrain is uneven then patches can't be so large that they don't accurately follow the undulations.
- Use Camera Clipping to cull trees that are not in the camera's field of view. If you have reflective items in the scene, make sure you add some Back Offset to retain some trees behind the camera.
- Use Camera > Density Falloff, Depending on your angles you may find you can drastically thin out the number of trees far from the camera without it being noticeable in the render. Check out the documentation for these features here.
- Optimise materials as much as possible. Leaves with Opacity maps can slow down renders so try to avoid them. If you can't you may find that changing the opacity mode to Stochastic, or Clip will speed things up. There are some more tips for material optimising in our FAQ here.
- For large grass areas I like to find an appropriate aerial photo or a field, meadow etc and use it with Forest Colour's Get Colour From Map feature, there's a tutorial on this here . This also means you may be able to thin out the 3d Grass and leave only the texture when it's far enough from the camera that you wouldn't notice.
- If you have multiple camera angles, use state sets to toggle on and off layers and objects as and when they're needed.
- Points-cloud display mode will keep your viewports fast, but with loads of objects you may occasionally experience some slow-down. To improve this you can lowed the density of the Points-cloud globally from any FP objects Camera rollout. Proxy display mode can often be faster, but of course you lose the nice preview.
- Consider dividing very large scenes into multiple files and use XRefs to combine them. This can make thing more manageable and is helpful if the scene is being worked on by multiple artists.
- The combination of V-Ray 3.3 and Forest Pack 5 (available as a beta at the moment, but released very soon) offers significant speed improvements over previous versions. In our tests between 40% and 100% improvements.

I hope that is of some use. If I think of anything else I'll post it here and if anyone else has anything to add please feel free. It's an interesting topic and there are many approaches.

Many thanks!

Paul Roberts
iToo Software