Digital Art Zone

Two images, indentical light at 100% the only diifference is one has ambient

There is no increase of light when ambeience is engaged.

The only time that I know of when Ambience increases light output is when GI is used.

and last a sphere with a transmap applied

A little late to the party, but yes - I do recall that at some stage Ambient had to be set to On before the UberArea light would actually emit light.  I’m not sure when that changed but seeing as the default setting after application of the shader is/was for it to be off it is a happy update in my book!

Simon I could kiss you but I would wager you don’t have the legs for it.

I agree a welcome change that sneaked by me….

Szark - 27 December 2012 05:03 AM

Simon I could kiss you but I would wager you don’t have the legs for it.

I agree a welcome change that sneaked by me….

Oh, but I do have the legs for it ... they’re ruddy good at running away!

I only noticed it when I did a render using UberArea lights, lit blue touch-paper and retired for the night in the certain knowledge that it would take ages to complete.  When I woke it was with the jolting certainty that I’d forgotten to turn on Ambient and I’d have to cancel and restart ... imagine my bouncy happiness (also confusion!) when I noticed that the lights were lit!

Szark - 27 December 2012 04:53 AM

The only time that I know of when Ambience increases light output is when GI is used.

That’s the problem! It shouldn’t do that.

prixat - 27 December 2012 04:14 AM

a couple of ways round it, I reduced the intensity to 0 and just relied on ambient.
(or you could reduce the overall exposure, that’s labeled ‘Gain’ in the render settings)

So for now ‘Ambient’ gets a reprieve

If anyone has a use for diffuse or opacity in an arealight I’d like to see it.

Ha! a challenge.

Also, shame on you for cutting the poor woman in half; there are laws against that you know…

Edit: hrmph forgot to say what I wanted to say…

So here goes; the burned out specular highlights may not have anything to do with light intensity (I’ve found that 100% for area-lights is not very bright at all) but more with specular maps or more to the point not having any…

prixat - 27 December 2012 05:34 AM

Szark - 27 December 2012 04:53 AM

The only time that I know of when Ambience increases light output is when GI is used.

That’s the problem! It shouldn’t do that.

 

I know you know more than me about all this so could you help me out by expaining why it shouldn’t…pwease.

SimonJM - 27 December 2012 05:15 AM

Szark - 27 December 2012 05:03 AM

Simon I could kiss you but I would wager you don’t have the legs for it.

I agree a welcome change that sneaked by me….

Oh, but I do have the legs for it ... they’re ruddy good at running away!

I only noticed it when I did a render using UberArea lights, lit blue touch-paper and retired for the night in the certain knowledge that it would take ages to complete.  When I woke it was with the jolting certainty that I’d forgotten to turn on Ambient and I’d have to cancel and restart ... imagine my bouncy happiness (also confusion!) when I noticed that the lights were lit!

LOL

What a nice surprise Simon…I really thought I was going more mad than I am already with this and it does surprise me that some of the other users had no idea about this. This was something I learnt in my first year.

prixat - 27 December 2012 03:54 AM

...and got an image with 200% and some burnt out highlights:

Yeah, that’s what I’d expect to happen with a surface that has diffusion, specularity, and reflection tuned on.  It’s very easy to get over-lighting and blow-outs, when those three add up.  It usually takes a bit of tweaking of the relative strength multipliers to get it to look right.

None of that changes the fact, though, that the ambient settings of a surface shader have no influence whatsoever on the light emitted by an area-light shader attached to the same surface.  They are two separate entities.

Here’s a simple test bed that shows it: a pure white plane, ball and cube, lit by a planar area light, emitting pure green light and having pure red ambient colour. If the two mixed, the scene should be lit in yellow - but it is not.  Only the colour set on the light shader has any influence on the actually emitted light.

Thank you all for the input I found in this thread. I now have a better understanding of how area lights work. Gonna experiment a little bit when I get home. I usually use them to light up stuff from 3-D-C at Rendo but I get mixed results…

I’ll have to check, but I think that Opacity can be used to give an ‘invisible’ emitter…in other words set to 0 should turn off the visibility of the item without affecting it’s light output.

Yep, exactly what it does…

Render 1 Sphere opacity is 100%
Render 2 Sphere opacity is 0%
Render 3 is using the ‘eye’ icon to turn off the sphere’ visibility…

All three are rendered with ‘low quality’ render settings for maximum speed…

mjc1016 - 28 December 2012 09:18 PM

I’ll have to check, but I think that Opacity can be used to give an ‘invisible’ emitter…in other words set to 0 should turn off the visibility of the item without affecting it’s light output.

Yep, exactly what it does…

Render 1 Sphere opacity is 100%
Render 2 Sphere opacity is 0%
Render 3 is using the ‘eye’ icon to turn off the sphere’ visibility…

All three are rendered with ‘low quality’ render settings for maximum speed…

There’s an option in the Arealight shader called “Fantom”, turn it “on” in the surfaces tab and you don’t have to mess about with Opacity, the pic is a quick spot render showing the Area disc lighting up Genesis, as you can see fantom is on.

Bejaymac - 28 December 2012 10:20 PM

mjc1016 - 28 December 2012 09:18 PM

I’ll have to check, but I think that Opacity can be used to give an ‘invisible’ emitter…in other words set to 0 should turn off the visibility of the item without affecting it’s light output.

Yep, exactly what it does…

Render 1 Sphere opacity is 100%
Render 2 Sphere opacity is 0%
Render 3 is using the ‘eye’ icon to turn off the sphere’ visibility…

All three are rendered with ‘low quality’ render settings for maximum speed…

There’s an option in the Arealight shader called “Fantom”, turn it “on” in the surfaces tab and you don’t have to mess about with Opacity, the pic is a quick spot render showing the Area disc lighting up Genesis, as you can see fantom is on.

Yes, Fantom works, too…but with the Opacity, you can still use maps to give a pattern to the emitter,,,just create a normal transmap and enable Ambient, with a bit of color and you have a shaped, glowing emitter…

While not quite the same, mesh lights/area lights are loads of fun.  I once modeled a light bulb, down to a simple filament.  Then used that in a flashlight, with a carefully modeled parabolic reflector.  Then I rendered it in Lux, with an volume defined.  The reflector was set to a mirror material, the filament was a mesh light and the bulb was a glass material…and when all was said and done, it looked great…but I didn’t get a chance to save the final image, as my network went down.  I should go back and render that one over again…I should have the scene file somewhere,  I know I’ve got the models. 

I wonder what it would be like doing that in DS 4.5 with UA

Or something like this…

Two area lights…one overhead and other is the ‘screen’ with an transmap and the ambient turned on…that’s over top of a slightly large square primitive, with a slight amount of ambient strength (5%, I think) in the same green as the the light color.