Rendering Best Practice

Forest Pack includes native geometric shaders for the renderers listed below, making it possible to render scenes with millions of high poly trees, meshes and proxies:

  • Arnold
  • Mental Ray
  • V-Ray
  • V-Ray RT
  • Maxwell Render
  • Octane Render
  • Arion Render
  • Corona Renderer
  • Thea Render
  • Moskito Render
  • Redshift
  • Fstorm
  • Final Render

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

Boundary Checking > Edge Mode is compatible with V-Ray, Corona, Arnold and Mental Ray. If this mode is used with unsupported renderers, point mode is used instead. 

- To use Boundary Checking mode with Mental Ray, Arnold and Corona, it is necessary to add a Forest Edge map Map to the material's Opacity input. 

- 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.

- When possible, use Max 64 bit. The 32 bit versions are very limited, and you may get memory errors when rendering complex scenes.

- Don't mix 32 bit and 64 bit environments for rendering, you would 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 This plugin, based on Shadow maps, was written for Scanline renderer but is obsolete with the new rendering engines.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 assignthe main light in the Shadows rollout.


  • To use Forest Color and Forest Edge maps with Arnold, you will need to turn on Legacy 3ds Max Map support in Render Settings->System.

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.
  • In Forest Pack 6, Material->Forest Shader parameters are removed from the interface. These are only used for billboards in Mental Ray and if needed, you can modify them from Maxscript as: fastopac, tracedepth, opaclevel, selfillum, irradiance.

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 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.

- Forest Color using "Element" mode is not compatible with Distributed Rendering. Instead, this feature works fine rendering locally.

- Rendering times with more than 500.000 items may grow exponentially. However in the latest Max releases (2014 and above), we have noticed improvements on this limitation. If you plan to scatter large distributions, we suggest you make your own tests, to know the limitations of the render engine.


- 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. In our test scenes, we have found that meshes usually render slightly faster than proxies.

VRayRT / Maxwell Render / Octane / Arion / Thea Render

Due to technical restrictions, support for these engines is limited and several features are supported. 

You can find the compatibility list here.