Image based lighting

[nbk2]

I have searched the forums for IBL or image based lighting. There was just one thread where colour was bounced off clouds.

Now this is nothing I believe in is taking over the world, or I now majorly want to use. It's just an experiment.

Below are several test images on how to achieve it to a certain degree. You just take a 360 image and put it on the background sphere. Make the sphere smaller and turn on the luminosity.

I am relatively sure it isn't just the environment light. BUT this has to be left on. BUT when you leave envronment on without having any luminosity on the image, it became black. Additionally if I ramped up luminosity in the default shader the image became brighter.

I thought it works ok for an overcast sky..

To have the image around the landscape I deformed the planet to essentially a cloverlike surface, so I can make the background sphere small enough to fit around. You see the setup in one of the pictures.

Should I have reinvented the wheel, well apologies. I tried to find it in the forums.

[Oshyan]

You're right that IBL hasn't been tried much, if at all. I would guess this is, at least in part, because TG itself is often used to create IBL sources for other apps, and IBL in general is a stand-in for larger environment lighting which TG2 already simulates very well. So IBL is not necessarily that commonly needed (in theory). Also the GI system in TG is not well setup for IBL, so you're not going to get ideal results from it. But it does work if, as you discovered, you use an image with luminosity on the background sphere.

The "Enviro Light" is just a GI lighting calculator. The reason you get no light when it's turned off (if you have no sunlight or other actual light source node) is that the GI isn't being calculated. When it's on it will calculate GI contributions from any light source, including luminous surfaces. So to get lighting with *only* your luminous surfaces, just disable any other light sources *besides* the Enviro Light.

- Oshyan

[nbk2]

You're right that IBL hasn't been tried much, if at all. I would guess this is, at least in part, because TG itself is often used to create IBL sources for other apps, and IBL in general is a stand-in for larger environment lighting which TG2 already simulates very well. So IBL is not necessarily that commonly needed (in theory). Also the GI system in TG is not well setup for IBL, so you're not going to get ideal results from it. But it does work if, as you discovered, you use an image with luminosity on the background sphere.

The "Enviro Light" is just a GI lighting calculator. The reason you get no light when it's turned off (if you have no sunlight or other actual light source node) is that the GI isn't being calculated. When it's on it will calculate GI contributions from any light source, including luminous surfaces. So to get lighting with *only* your luminous surfaces, just disable any other light sources *besides* the Enviro Light.

- Oshyan

Thank you for your confirmation that is IBL. I haven't tuned it, but the sun was switched off. As you mentioned Terragen does brilliantly without it.   I was just interested.