using primitives as iray lights

Nathuado

I've been trying to make my own lights in Iray by creating primitve planes and applying light shaders to them, from "Iray Real Lights".  I was hoping to render the picture without the physical objects appearing by selecting 'off' for the "Visible in render" option and 'on' for the "simulation" option in the display parameters for each object, but that doesn't seem to work and I end up with a black silhouette.  Is it possible to render the scene and keep the light emitting from an object without showing the actual object?

Umi no Senshi no Ishi

Search the forums for "Ghost Lights". There was a step by step on how to do what you describe. I think this is the link: https://www.daz3d.com/forums/discussion/127056/ghost-lights-interior-lighting-tutorial, as the "Ghost Lights" Product came out that does all the steps for you. Also, you could try I believe on the surfaces tabe of your plane, lower the cutout opacity to a very low (but not zero) number, like .00001.

The link gives a more detailed step by step.

Hope that helps.

fastbike1

@Nathuado "I've been trying to make my own lights in Iray by creating primitve planes and applying light shaders to them"

The Photometric Spotlight has parameters to add geometry. When you do this, they give the same results as a photographer's softbox, and the "visible in render" works like you expect.

Nathuado

Thanks for those helpful comments!  I'll try both.  'Ghost lights' sounds exactly like what I'm trying to do.

jestmart

Spotlights with one of the geometry options will have the geometry visible in relfections and when viewed through transparencies.  When you really don't want lights visible they need to be ghost light emmissive panel or spotlight set to point.

Oso3D

Note that ghost lights will lack highlights (which are reflections, after all).

fastbike1

At the end of the day, all of these issues go away if the lighting is not in the camera's view, including reflections. A little time as a photographer will teach this.

jestmart

Highlights are weaker and more diffused with emmissive lights but are still there, making them more useful as fill or ambient light sources and not your main.

Member_257874

fastbike1 said:

At the end of the day, all of these issues go away if the lighting is not in the camera's view, including reflections. A little time as a photographer will teach this.

That's how one could do it. Or actually include the lights into your scene as real objects (like real world lights).

I had a similar issue when I wanted to render something in a room and the HDRI didnt light the scene because of the walls shadow. So adding a plane to the ceiling and making it a light helped somewhat. To make the plane invisible I noticed, as Umi no said, that as long as the light has a tiny opacity greater than zero, it emits light.