Vray Performance Tweaks

From a PDF I found while clearing out some stuff on my computer.

Two types of geometry - static and dynamic:

• Static is precompiled and will use as much memory as possible
• Dynamic is loaded and unloaded, memory can be limited.

Static objects:

• Fastest to render
• When selected as the default, all standard object types will be treated as static
• Purpose built dynamic objects (V-Ray displacements, fur, meshes etc.) will always be treated as dynamic
• Uses the most memory, no limits to the amount it will use
• The least stable of the geometry types

Dynamic objects:

•

• Middle ground between speed and memory use
• When selected as the default geometry V-Ray will treat any static geometry as dynamic as best it can
• Dynamic objects are subject to the dynamic memory limit, that can be set by the user
• The dynamic memory limit limits the amount of memory the threads use when rendering
• Generally the limit should be between ½ and ¾ of the total system memory
• Memory must be kept free for other max & system processes
• It is a delicate balancing act

Proxy objects:

•

• Are completely dynamic
• Subject to the dynamic memory limit no matter which default geometry setting is picked
• Geometry from V-Ray meshes are loaded and unloaded as and when required, to save memory
• Because of the constant loading and unloading the speed of the render suffers
• Slowest to render
• Most stable of geometry types
• Huge models can be rendered
• V-Ray meshes need to be setup before render time

Other memory tweaks:

•

• To help prevent getting bitmap errors, when using lots and/or large textures, use the bitmap pager inside 3ds max
• To save memory turn off the frame buffer when rendering
• If you need the frame buffer on during rendering, use the V-Ray frame buffer as this is far more stable than max's own
• For very large renders try and use vrimg files, a very stable raw image format than can be converted to .exr for loading into photoshop

Irradiance map min/max settings:

•

• Min/Max rates heavily affect the quality of the final irradiance map
• Min/Max rates also affect the time the irradiance map takes to compute
• Irradiance maps are resolution dependant
• Min/max rates differ for various render sizes

Min/max rates and speed:

•

• Irradiance maps are made up of points, that hold illumination data, V-Ray interpolates between these points to create the final illumination solution
• V-Ray places more points in areas that need more samples and less points in areas that need less samples
• In order for V-Ray to complete the process efficiently it needs to run several passes, determined by the Min/Max rates
• The difference between the Min/Max rate values determines how many passes will occur and the resolution of each pass
• Providing V-Ray with more passes enables it to make a better judgement as to where to place points
• Increasing the passes lowers the render time up to a point

Min/max rates and quality:

•

• Renders of differing sizes require different Min/Max rates
• Smaller images require higher Min/Max rates, Larger images require smaller Min/Max rates, for renders of comparable quality
• Do not fall into the trap of increasing HSph subdivs and Interp samples unnecessarily, they can increase the render times dramaticaly