Add a light and turn it off?

[Bruce Kieffer]

I'm trying to understand this. I drew a 1/2" thick glass top coffee table. I rendered it with Renderworks. After messing with the textures a bit, I finally get the glass to appear to have some depth. Next I want to add some shadows so I add a spot light. The appearance of the depth in the glass then disappears. Very odd, so I turn off the light, thinking that will return the lighting to how it was prior to adding the light. Not so, even with the light in the scene turned off, it still affects the lighting of all the objects. What's going on?

In the real world, a room with a window is lit by ambient light. I turn a light on in the room, the lighting changes. I turn the light off, the lighting returns to only the ambient light. This is how I think Renderworks should work.

[grant_PD]

I think the default light turns off when you have a light in the scene,comes back when you don't.

[Bruce Kieffer]

What is the default light? Isn't it the ambient light?

[grant_PD]

I think they are two different things. I think the default light is there to let you see if there are no light objects on. It goes away once you add a light object. The ambient light is just like a brightness slider for your screen (I'm speaking loosely here, but that's sort of all it does. It's akin to a color overlay in a photoshop file).

I always think it's best to turn ambient off.

[michaelk]

Not exactly. There is a default light attached to the "camera" that illuminates the scene so you don't have to set any lights to begin with to just see what you are working on.

As soon as you put in your first light, that light vanishes.

Not the same as ambient light. If you start with a blank drawing and turn off the ambient light, you can still render in open gl or render works and see the objects in the drawing.

But as soon as you put in one light, that becomes the ONLY light. **I believe** that deleting that light should make the default light come back.

If you want the glass to look like it has depth, take a look at HDRI sources. Then you only really need one directional light to make things pop.

mk

[Bruce Kieffer]

OK, I see the light setup is different than real world. I wonder how Renderworks determines the angle and settings of the default light? It sure looks like it's a directional light since there are highlights on left facing surfaces. I tested what MK suggests as an experiment. First I extruded a white filled "wall" behind the coffee table. Then I turned the ambient light and directional lights off, rendered FQRW, and the objects are all black except the glass top. Next I deleted my directional light and rendered again. There is obviously a hidden default light in the scene.

[grant_PD]

Yes, you have it. Best to move forward, put your own light in the scene, so that they phantom default light goes away.

[grant_PD]

Other things that are not "real world":

You won't get bounces and what I consider to be ambient illumination unless you use what they call indirect lighting. Which is why I say to turn the ambient slider to zero of set it off. Turn on your indirect lighting and set it to the low bounce settings and you'll get closer to what you're looking for in terms of ambient lighting.

[Bruce Kieffer]

Thanks for all the help. I'm getting a copy of the Remarkable Renderworks book to review and learn more.