Using Irradiance Particles with Final Gathering

You can use irradiance particles together with final gathering by:

1. Setting Indirect Illumination Algorithm to Irradiance Particles / Final Gather on the Photon Global tab of the mental ray Render Options Property Editor.
2. Enabling irradiance particles on the Irradiance Particles tab.
3. Enabling final gathering on the on the Final Gathering tab.

However, the final gathering settings take precedence over the irradiance particle settings. In particular, the irradiance particles' Intensity and Interpolation settings are not used.

You cannot combine irradiance particles and global illumination.