Cycles Light Decay

Lights in cycles have no decay - and i didnt see any option to change that?

Yeah… Rhino has for some reason never had fall off on it’s lights, something which is strongly needed to be able to make realistic renderings. And therefore, as I understand it, Cycles too was forced to adapt to Rhino’s lack of decay, so Raytraced and the slow Rhino Render will look as much as each other as possible.

So tell them why you need it and why it is important to implement it and add some screenshots and examples if you can.

Sorry - just to understand - who is them?

“them” = the great minds at McNeel :slight_smile:

Is there some official statement on that?

Indeed Rhino lights don’t have fall-off, they are constant light. From :

NOTE : Rhino’s user interface only uses constant attenuation so that adding a light reveals everything, no matter how far away the light source is from any given piece of geometry.

Well that makes having cycles kinda pointless, doesn’t it?

In case McNeel officials really want customer stories about that, maybe you can forward this to them:

I was very excited to hear that cylces was to be implemented in Rhino. Not only for my own work, but for the 50+ students i teach throughout the year. Unfortunately there were certain basic features missing from the start, and as i learned now, they are not implemented by choice. Therefore i am forced to move back to maya / max as far as my students are concerned.

It it not much of a point holding on to errors that were done in the past. Especially when pretty much every software package on this planet moved beyond constant light attenuation 15 years ago. (And proper gamma workflow 5-10 years ago)

This makes cycles unfortunately useless as a tool, especially in teaching, as it breaks compatibility of concepts with the industry standards.

As far as i am concerned - you are loosing customers with this backwards looking policy.

@nathanletwory - thanks for your support in this forum, and i hope you can do something about this situation at some point


I’m quite sure that at some point we’ll be able to have the primitive lights do fall-off as well. Until then you can use mesh lights with the Cycles Emissive material

If you don’t see the Cycles Emissive material in your material type list you need to run _TestShowPrivateContent. You can assign this material to any geometry - that object acts like a light in Raytraced. For fall-off you can use the values 0 = no fall-off, 1 = linear, 2 = quadratic.

The interface for this is not intuitive nor very easy, but you should be able to get somewhere.


And therefore it is a huge hurdle because you can’t teach people to use hidden features. Easter eggs are for the select few who spends their time off reading and thinking about stuff like this. The masses needs stuff to work as natural and strait forward as possible or they will not use it and rather look for something else.
(It’s one of the huge reasons propper cameras are loosing ground to cell phones even for vacation pictures. “People” want “good enough”, “affordable” and “right now”)

Aye, I suppose you could call the constant energy the cellphone of rendering :wink:

Touché… but I disagree because that is not how real light works as all lights have a falloff and with Rhino we have to work around that, which makes it more difficult than it should be. But well played!!! :smiley:

You know that I know that “real” lights would be much better. But that is for the future.


Yes please!
And remember that in all Rhino 5 users world, who still hasn’t upgraded, Rhino 6 IS the future, so can we have it now? :wink:


If you mean by now the moment that Mount Everest is a smooth, rounded peak. Sure.

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Any updates on light decay? or at least an eta?

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Using the Cycles Emissive material is currently the only way. No ETA yet (still on holiday, so not going to try think about that :wink: ).