Second License 50% Off

You add a second license to your order at half price!. Press OK to add this offer to your order.

or

Forest Reference
Forest / Reference / Rendering Best Practices

Rendering Best Practices

Forest Pack includes native geometric shaders for multiple render engines (currently: Mental Ray, VRay, Maxwell Render, Octane, Arion and Thea Render), making possible to render scenes with millions of high poly trees, meshes and proxies. Usually these techniques push the rendering engine to its limits. In the following notes, we include technical information that can help you to optimize your renderings, and avoid some problems.

Common Tips

- Minimize the use of opacity maps in your plants. Raytracers are slow computing transparencies, when possible use mesh leaves instead masked textures, although number of polygons be higher. If you need to use opacities, disabling the filter map may help to speed up the render.

- You can use the Material Optimizer included with Forest Pack, to converts the materials to VRay/Mental Ray and tune up the texture maps.

- Don't mix 32 bit and 64 bit environments when rendering scenes with Forest, you would to get unexpected results. Because the different numeric precision of both architectures, some problems may appear as: misaligned objects, color variation and others. Generally, it's not a good idea to mix 32 bit and 64 bit nodes in 3DS Max, to avoid issues as rendering flickering or glitches in procedural textures.

- XShadow is not compatible with Mental Ray and VRay. This plugin, based on Shadow maps, was written for Scanline renderer but is obsolete with the new rendering engines. Instead it, use raytraced shadows in Mental Ray or VRayShadow in VRay. If you use billboards, don't forget to assign the main light in the Shadows rollout.

Mental Ray

- To get acceptable rendering times in large scenes, it's necessary to use BSP2 as raytrace method. It is available only in Max 2009 or greater. For previous versions, or small-to-medium size scenes, you can use BSP instead.

- Always disable "Scanline" checkbox (in "Rendering Algorithms" rollout), and we suggest to enable "Use Placeholder Objects" (in "Translator Options"). These settings are specially necessary when rendering complex scenes with large number of instances.

Note 1: The use of Placeholder objects is incompatible with the G-Buffer channel "Coverage". This channel is used in the RPF format, for some Render Effects and by third-party plugins as "PSD Manager" from Cebas. If the Placeholders are enabled, the channel is rendered as pure black. Unfortunately, this is a Mental Ray limitation and there are not known workarounds for it.

Note 2: We also found that the Placeholder objects feature crashes with some types of proxy elements used on Civil View (3DS Max Design), specifically the Street Lamps. Be care if you use these elements in your scene.

- You can use assign billboards, meshes, mrProxies or any other object (as RPC) for your trees. In our sample scenes, we have not found differences (in render time or memory used) between using meshes or proxies, but we suggest that you make your own tests.

- Mental Ray versions before to Max 2010 was not fully stable using a high number of objects (above 100.000 trees). Some errors would occur as crashes, "accessing unknown tag" messages, etc. This problem has been solved in latest Max releases.

- Rendering times with more than 500.000 trees grows exponentially. This seems to be the limit of Mental Ray handling large number of instances.

mental ray

V-Ray

- V-Ray native shader requires Max 9 with VRay 1.50 SP3 or greater.

- To render high-poly objects or proxies, increase the Dynamic Memory Limit from the default value to a percentage of your total RAM. The optimal value depends of the complexity of the scene, but usually a minimum of 2000 or 3000 Mb. is required. In V-Ray 2.0 and later, you can set this to 0 to remove any limit in that case, V-Ray will take as much memory as needed.

- You can use billboards, meshes, or V-Ray proxies in Forest. Actually, other types of objects (as RPC) don't work. In our test scenes, we have found that meshes usually render slightly faster than proxies.

mental ray

VRayRT / Maxwell Render / Octane / Arion / Thea Render

Due to technical limitations, support for these engines is more limited than VRay / Mental Ray, and the following features are not be available for them:

  • Forest Color.
  • Forest Material.
  • Material->Random Tint.