Invisible light plane
in The Commons
I'm trying to use a light plane but I need the plane itself to be invisible. But when I change it's opacity to 0, the light goes away. Is there a way to have a rectangular source of light that is not visible? I've tried a basic plane with the Emissive shader attached to it, and the built-in Light Pane, also with Emissive shader because I couldn't see any other way to get it to emit light.
Sorry if this is a basic question, but I'm still pretty new to 3D rendering.
Thanks,
Harry

Comments
Iray:
Geometry > Cutout Opacity: 0.010
Emission > Luminance: 300-500
Emission > Luminance Units : Kcd/m^2
...and here I thought that Cessna, Piper, or Beechcraft got into the stealth market.
http://www.daz3d.com/iray-ghost-light-kit
A great product.
Sadly no longer on offer; the upside is you know it is possible as that is what it does, and other stuff.
I need someting similar, but I want my light object to be visible but not casting shadows. After all a non-material light source (like a flame) don't.
I couldn't agree more. This toolkit is a great time saver.
Kindred Arts posted a tutorial on how to create Ghost Lights here, which you may find helpful. (I used what I learned in that short tutorial thread before the Iray Ghost Light Kit was released, but I still bought the product when it came out, and consider it one of my better investments.)
...flames do cast shadows just like any other light soruce.
Where there is light - there is shadow!
Why isn't the ghost light kit available?
It is still available but past the initial intro pricing.
I appreciate all the comments.
PedroC, I tried what you suggested but I still ended up with a visible plane, just transluscent. That may have to do with the fact that I'm using red light, or because I'm just not letting the render finish (it takes a very, very long time). But thansk for the suggestion.
I bought the Ghost Light kit and it did what I needed.
Thanks!
And I thought Wonder Woman was going for a smaller aircraft.
For those wanting to do it themselves, in a pinch, PedroCs advice is good but I would change one thing:
Geometry > Cutout Opacity: 0.010 0.001
The ghost lights do this but they also do some other cool things. First, they have a parented "arrow" that shows the direction of the light. It's not always obvious with a plane which way the light will shine when you roll your own; so that's a great thing. Second, there is a setting to let the lights be visible for placement and sizing, then you make them invisible with one click. Convenience. Third, it has a bunch of presets for brightness and color. All of this you can do manually (and I used to regularly) but I got the ghost lights because they speed up the process and idiot-proof it (which I need!)
another recommendation for the ghost light kit here---it's wonderful to work with. :)
j
...exactly, which makes them more efficient for the workflow.
...must be economics, just like the airlines' reason for moving to those smaller cramped regional jets.
I thought though for superheroes, money was never an issue (except where Peter Parker was concerned).
I apreciate your advice. I played whith the limit of cutout because when you lower the opacity you lower the light intensity too. 0.010 is the limit to not to see the mesh of course you can play whith your own values, most people use a 0.001 value.
there are people using a luminance value of 100 what is a soft light value in my proofs. that's the reason I pointed a 300-500 value for luminace, of course the best is find your own accurate values in your images.
Other thing to point out is the use of Kcd/m^2 units , you can use the units you want, the advantage of Kcd/m^2 units is you can use low numbers vs 10^6 numbers whith cd/m^2 for example.
harry_b0ae952cfb, i'd never played whith colored ghost lights so i can't tell you my experience.
Excelent, works fine for me.
You can make an emissive surface invisible by adding a small black image to the cutout-opacity channel.
The first image shows a simple scene lit by an emissive sphere. The second scene has the same lighting but the sphere is nowhere to be seen (scene?).
As you can see, I've just created a small black image (say 100 by 100 pixels) and popped it onto the cutout-opacity channel.
No third-party products required.
And I was beginning to think that the discussion would be about ultraviolet or infrared illumination.
No need for an image either, just set the value for the Cutout Opacity to a small but non-zero number as has been mentioned above. The Ghost Light set adds convenience.
This :D
The object can still catch light/be seen at very low opacities and the light it emits is affected as well which is why I prefer the black image. It can be a 1x1 pixel image.
Ghost lights for Halloween, perhaps?