MtoA: Can't render multiple lightgroups

[Anonymous]

The documentation says to create light groups (obviously), create an aov and then simply add your lightgroups to the Light Groups List in the aov node. However, only one light group ever renders. I've tried every combination of adding them from the drop down list, inputting manually, changing the names, adding them as a script in the light Path Expression, etc.

Is the documentation just really out of date?

[Stephen.Blair]

Did you set the light group names on the lights?

[Anonymous]

I did, yes. I have found a workaround by creating aovs for every light, which is a pain, but it works.

[Stephen.Blair]

I do light groups all the time, so something is not right.

[Anonymous]

Perhaps I'm doing it wrong then? Could I ask if you use the method in the attached picture? I have three light groups, red, green, blue, and I select them in the aov's light groups list. Only one of these (say, green) will render. Thanks.

[Stephen.Blair · Accepted solution]

If you use the default <exr> driver for your light groupg AOVs, then you need to enable Merge AOVs (Render Settings > Common tab).

[Anonymous]

ah, I didn't have Merge AOVs enabled. That works now. Thanks.

[metatoma]

Thanks!

I was bypassing what I thought was a bug of some sort by doing custom aovs and light path expressions... when all it was really was activate the merge of aovs wihtin exr.