[RonB]

Did you know that an emitter set to a negative value will take away light from the scene to the same intensity as if it were set to a positive setting? Negative emitters in Maxwell work exactly as negative lights in other programs. It is a trick worth knowing and experimenting with. I don't believe it is mentioned in the manual.

I stumbled upon this sometime ago and was reminded about negative emitters by Lior Segal in an email. Thought I would bring it up here.

Cheers, Ron

[JorisMX]

WOW!!!

Ron this is so Awsome! I was looking for something to make more dramatic lighting for a while now!

[JorisMX]

I was eager to test this, but unfortunately this is not possible with the current Cinema4d Plugin

[tizxx]

Sorry man I not understand you ...

It's also pollible to us with Multilight System ?

can you post a little sample image or scene ?

thank you.

[JorisMX]

I tried it in Studio now and it is not working there either.

What I tried so far:

- Changing watts and/or intensity to negative values [values always jump to 0]
- Setting luminance values to negative values (lumen,candela,lux & nit) [values always jump to 0]
- Rendering with multilight and entering a negative value in the faders (this always results with a black (i.e. value of 0) emitter)

Ron, please let us know how you did this!

[RonB]

BIG MISTAKE ON MY PART...I APOLOGIZE FOR THE MISPOST...I WAS WRONG ABOUT NEGATIVE EMITTERS...YOU CANNOT SET A NEGATIVE VALUE...

A ZERO WATT SETTING WILL WORK...

[JorisMX]

We could post this in the Wish List section, however I believe NL won'T do something like this as it is not physicly correct...or is it?

Black Holes absorb light too!

[johann.dugge]

an emitter set to a negative value will take away light from the scene to the same intensity as if it were set to a positive setting? Negative emitters in Maxwell work exactly as negative lights in other programs.

So in other programs that allow you to do this, if you have a GI lit scene and place such a negative emitter, the shadows it casts are brighter than the surrounding areas?
What's a typical scenario where one would want to use negative emitters? And what rendering packages do this?
Certainly an interesting concept.

[RonB]

johann, Lightwave will do it. All one has to do is set a light to a negative value and it will take illumination from the scene. For instance, you can place a point light to darken areas that you might not want illuminated, say in a dramatically lit character study.

I did a scene sometime back and as I remeber...I was experimenting with negative emitters in it. I posted this thread before researching it further. I should not have done that...again, my mistake...sorry.

[RonB]

O.K. and this works: An emitter with a zero watts setting will pull illumination from the scene. My mistake that I thought I remembered it possible to dial in a negative value...you cannot...but a zero watt emitter will darken the scene.

Here is the original post from 2006:

http://www.maxwellrender.com/forum/view ... light=mime

Here is an example:

Same lighting in each, the Sky Dome. You can see the edge of the emitter between the objects in the right image and the effect. Normally I would use Tom's method for hiding the emitter from the camera view.



[/img]

[Thomas An.]

Can you replace the emitter with a black lambertian (RGB 0) ?
It would probably have the same effect.

[RonB]

Could you make the black lambertian object invisible to the camera and retain the effect?

[Hervé]

"invisible to cam" in object panel won't do..?

[tom]

Ron, the geometry is blocking the light flow because the objects hidden from camera still contribute to the scene. It's not about negative emission.

Btw, I'm sure you'll like this:
http://www.theatrecrafts.com/humour_darksuckers.html

[RonB]

Tom, Boy that article sucks!

O.K., so the plane is just blocking light?....Geez, now I feel like a real nit wit!
Sort of like I yelled, "Eureka!" and my pants fell down....