Distant lights vs Ghost Lights

jmucchiello · April 20

I have a ghost light plane in a scene with invisible to primary rays casting a shadow from a distant light. Are distant lights not considered "primary" in this case? In the image, you can see on the left the IRAY preview with the plane on and off camera. On the right, the display parameters show the plane should be invisible to primary light rays. And the view from the distant light is shown as well.

I tried this in 4.24 and 6 Beta. Same results. Are distant lights not "primary" rays of light?

Richard Haseltine · April 20

Are you setting the refraction for the plane to 1 for index and weight? And setting the Gjost Light factor on the items that should not be taking the shadow to over 1?

jmucchiello · April 20

I didn't touch refraction and have never touched it in the thousands of ghost lights I've created with /Scripts/Utilities/Create Advanced Iray Node Properties.dse

I just experimented with refraction. Changing refraction index has no effect. The shadow noticably fades at refraction weight 0.2. Refraction weight of 1 does eliminate the shadow.

I've never seen this before. I guess I never heard about the refraction step for making a ghost light. I've never needed it before. HDRI doesn't do this. If I turn off the distant light and turn on Dome and Scene in environment, the shadow goes away for all refraction weight values. I can't recall if I've ever combined ghost lighting and distant lighting in this manner before.

And I thought I understood Ghost lights. :) Thanks.

Richard Haseltine · April 20

I use Creating a "Ghost Light" - Daz Studio 4.21.1.26+ - Daz 3D Forums as my reference (and needed it to remind me about refraction)

jmucchiello · April 20

Yeah, I've read that before. Have it bookmarked, too. Just thought "I knew it all." And of course there was something I'd missed all these months gone by. Knowing it all is never true, it seems. Now I know that. :)

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Distant lights vs Ghost Lights

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