LPE presets

[chris_elmer]

Hi,

Currently I'm generating light selects (per light aovs) with the following lpe syntax:

C.*<L.'lpetag'>

This works, but it's also including the GI from the entire scene (other lights, self illum gi etc).
I only want to collect that specific light's contribution to the scene. Am I missing something in the LPE?

Thanks,
Chris

[LeoYfver]

Had the same issue, it is a shortcoming of lpes with lightcache, the issue will go away if you use bruteforce bruteforce. Will let bdancer answer more in detail.

[chris_elmer]

Thanks for that. I'll switch over to brute force gi.

[chris_elmer]

I have a simple example scene where I've switched to brute force, but the per light aovs still include the GI from the emissive ground plane. Beauty on left. Blue light aov on right (the red GI is still in the aov).
I did switch back and forth from Light Cache to Brute Force but got the same result, so perhaps something is wrong with the setup.

[bdancer]

Yes, this is the current limitation of the light tag implementation. We're working on the proper light tag support, but it's not yet there...

[bdancer]

There is LPE tab in vraystandardrendervar, there is a drop-down menu next to the LPE expression with examples.

[chris_elmer]

Thanks bdancer, I believe I have the correct LPE expression (C.*<L.'lpetag'>). But in my example scene even with brute force as the GI method, I still see the self illumination (camera visible self illum and GI from self illum) in the light select.
s there something wrong with the my setup?

[bdancer]

> I believe I have the correct LPE expression (C.*<L.'lpetag'>)
> But in my example scene even with brute force as the GI method, I still see the self illumination

There is nothing wrong with your syntax. "this is the current limitation of the light tag implementation."

[chris_elmer]

Ok thank you. Is there a non-lpe way of getting per light aovs in Solaris? Like the light selects method in Maya/Vray?

[bdancer]

> Is there a non-lpe way of getting per light aovs in Solaris? Like the light selects method in Maya/Vray?

Currently no. I haven't found a convenient way to specify a list of lights. Basically, I could add some string parameter with some reg-exp syntax, but it'll basically do the same...
Current light tag implementation is basically doing the same - tag matching and adding lights with matched tag to the light select element.

[LeoYfver]

chris_elmer

to get rid of the self illumination you can try this lpe (C.*)-(C.*O)<L.'shot_sun'>. It should tag the light and exclude all self illumination

about getting lightselects you can do it with a for loop and using %type:Light to loop through the lights and with python code add the name of each loop into a rendervar. There is an example of this in the karma rendervars

[chris_elmer]

Thanks bdancer and @LeoYfver
Yes I've got a loop running through any lights with a defined lpe tag. I was just looking for a way to get the correct aov output. I'll give your LPE expression a go, thank you!

[Nevoreko]

Hey,

Bumping this post to ask if LPEs are still the only way of getting light selects working in vray for solaris? And if it has any significant rendering performance impact?
Karma seems to be doing the LPE way as well, but I just wanted to make sure, as all the vrayStandardRenderVars are of raw type and not LPE, so it needs a constant custom LPE setup to have them working

Thanks, Marvin

[bdancer]

> Bumping this post to ask if LPEs are still the only way of getting light selects working in vray for solaris?

Yes.

> as all the vrayStandardRenderVars are of raw type and not LPE

There is a whole LPE tab in that node...

[Nevoreko]

Hey, yes I am aware of the LPE tab, but it didn't sound like it was the intended default to use, the doc states that there might be some performance hit, but in our environment we rely a lot on light selects so we would need all our renders to use LPE by default, so I would like to make sure that there is no significant road block by going that route

Thanks, Marvin