Iray performance tips to reduce fireflies


Picked up a few tips on the  Nvidia IRay forum

There is an Iray Performance tips PDF that suggests a couple of tricks to reduces fireflies.

Adjust texture resolutions to the scene requirements.

  • Textures compete with geometry for the GPU memory. The higher the resolution of
    textures, the less the memory available for geometry, and vice-versa.
  • High frequency textures at high resolutions may become a source of further noise
    and require more time to converge.

The total reflectivity (reflectivy * reflection_color) should be capped to 0.7. It’s OK to use a white reflection color with a reflectivity of 0.7. It’s also OK to use a reflectivity of 1.0 and a reflection color of 0.7.

At I found a maxscript filter firefly-removal-max-script that may help.

I’m tempted to design a custom filter in fusion to deal with fireflies in animated sequences. But unless things improve with iray I’m likely to move over to VrayRT for GPU rendering

iRay mBlur and pFlow Test

iRay motion blur dialog
I’ve been doing some tests to create a monster made of particles for a short film. I’ve been very impressed be the speed of rendering Motion Blur in iRay. It’s smooth and high quality with very little performance overhead.

Continue reading

Extra iRay tools for 3dsMax

A helpful guy from autodesk showed me some useful tools for 3dsMax and nvidia iray. A special iray material , and a maxscript that allows you to access a lot of features hidden from the default render dialog

iRay material plugin

There is a sticky thread on the mental images forum which allows you to download the plugin from their ftp site.

It has a host of features.

  • 3 layers: Glossy Coating, Metallic Flakes, Glossy/Diffuse/Transparent Base
  • Backscattering (for realistic fabrics)
  • Metallic flakes (for great car paint)
  • Sub-surface scattering
  • Thin film coating
  • Spectral dispersion
  • Anisotropy on each layer
  • Emission (self-illuminance)
  • Displacement, bump, round corners, cutout

iRay manager script

There are a bunch of hidden features in iray that can be access using scripted commands. The iRay manager script was originally written by Artur Leao then later updated by Thorsten Hartmann. As a result we now have two slightly different version of the script, as both parties seem to be now publishing updates independently.

  1. Resources
  2. Interactivity Performance
  3. extended progressive Options
  4. FireFly Filtering (to remove 1 pixel hot spots)
  5. Matte Ground
  6. Background
  7. Clay Render
  8. Save/Load Options

You can download Artur Leao’s version from his blog.

Thorsten Hartmann version is available on his web page.

The nividea forum also hosts a thread on iRay Manager script.

iray dev Blog

Nvidea have a site dedicated to iRay at

If you browse through the blog you can find the matte material for iray