Hello everyone !

Has anyone tried setting a geometry light in LOPs ?

I've set the type to “Geometry”
then added the path in : Base Geometry > Geometry

But it doesn't seem to work.

Do you have any advice ?
Thanks !

Just add a “PBR Emission” material to the object that's emitting light.

I don't see geometry light working either

adding emissive shader to geometry is just emissive geometry, whether you have Geometry Light in the scene or not, does Karma already support Geometry lights?

tamte
adding emissive shader to geometry is just emissive geometry, whether you have Geometry Light in the scene or not, does Karma already support Geometry lights?

I highly doubt it. I'm pretty sure those parameters are placeholders from the usdLux Schema.

Geometry lights in USD are indeed just placeholders ATM. It's difficult to support them due to limitations in Hydra.

Instead, Karma automatically turns any geometry or volumes into geo-lights under the hood, if emission is being used on the material.

- “Treat as LightSource” geometry property can be used to change this behavior.
- “Light Sampling Quality” geometry property can be used to adjust sampling quality.

thanks brians, that's good to know, however such “Light Source” doesn't seem to show up in Light Linker or Light Mixer
also can we tag lights and objects for LPE's and would such “Light Source” lpe tag work as a light tag?

Thank you all for your answers, this has been quite helpful !

tamte
thanks brians, that's good to know, however such “Light Source” doesn't seem to show up in Light Linker or Light Mixer also can we tag lights and objects for LPE's and would such “Light Source” lpe tag work as a light tag?

Hi Tomas
Those features are not supported yet. Once Pixar have done the work necessary for Hydra to support geometry-lights, then we will be able to move forward on them. We don't have a firm date on when that'll be unfortunately, at this stage it will not be in 18.5 at least.
Thanks

Almost a year since this topic was discussed. @brians do you know if there has been any development? geo/mesh lights are a staple of the lighting artist.

thank you

lor

brians

tamte
thanks brians, that's good to know, however such "Light Source" doesn't seem to show up in Light Linker or Light Mixer also can we tag lights and objects for LPE's and would such "Light Source" lpe tag work as a light tag?

Hi Tomas
Those features are not supported yet. Once Pixar have done the work necessary for Hydra to support geometry-lights, then we will be able to move forward on them. We don't have a firm date on when that'll be unfortunately, at this stage it will not be in 18.5 at least.
Thanks

Any news on this? thanks!

I have some doubts regarding how to use it. Emission intensity is ignored and intensity is only specified through color values?
Also, the illuminate objects check doesn't work, but I suppose that's remanent of the Mantra behaviour...

Please say someone has an update on this? Is there any way to get geo lights working in Karma?

@Healiosol, yes you can enable geo lights. You have to create materiallibrary LOP, dive inside of it, and create a MaterialX (for example) shader, enable emission - assign a material to the mesh with materiallibrary LOP or with assign material LOP.

- https://www.sidefx.com/docs/houdini/solaris/kug/lights.html#geo [www.sidefx.com]

Example using MaterialX:




Example using Principled Shader (rendering feels a bit slower compared to MaterialX):




Node graph:

здмит
это было очень полез

How do I use the lpe tag in your example?

brians

tamte
thanks brians, that's good to know, however such "Light Source" doesn't seem to show up in Light Linker or Light Mixer also can we tag lights and objects for LPE's and would such "Light Source" lpe tag work as a light tag?

Hi Tomas
Those features are not supported yet. Once Pixar have done the work necessary for Hydra to support geometry-lights, then we will be able to move forward on them. We don't have a firm date on when that'll be unfortunately, at this stage it will not be in 18.5 at least.
Thanks

Is this limitation still present?

Following up with the same question. will Houdini 20 support it? it does says lighting: geo lights

Does H20 support geometry/volume lighting?

bump, LPE tags for geo lights still a no no?

sekow
bump, LPE tags for geo lights still a no no?

you can tag geometry with LPE tag and then isolate in your AOVs
it works for geometry light contributions

the main limitation seems to be that the Split Per LPE Tag checkboxes don't parse geometry marked as lights, only light schemas and therefore they will not detect and create the AOVs for current workaroundish incarnation of geometry lights

so you have to create additional AOVs yourself with corresponding LPE that filters lights by LPE tag of the geometry light object

tamte

sekow
bump, LPE tags for geo lights still a no no?

you can tag geometry with LPE tag and then isolate in your AOVs
it works for geometry light contributions

the main limitation seems to be that the Split Per LPE Tag checkboxes don't parse geometry marked as lights, only light schemas and therefore they will not detect and create the AOVs for current workaroundish incarnation of geometry lights

so you have to create additional AOVs yourself with corresponding LPE that filters lights by LPE tag of the geometry light object

Is that with O event or L?