Light decay

[andeltoz]

Hi.
Is there a way to control the decay of light? I ask this because, at times, such as in the case of a lampshade, the light that reaches the ceiling is too intense compared to what happens in reality. Is there anyone who knows any tricks about it?
Maybe I don't know how to use Corona lights well?

[TomG]

The light falloff is physically realistic, and so cannot be adjusted - things to check are: is the scene built to a real world scale? Is the light source too large? (light energy is dependent on the surface area of the light as well as the intensity) Is the material on the receiving surface set up realistically, in particular albedo is not too high? (surfaces should not be 255,255,255 in diffuse for example, whether set direct or from a texture map) Can you share screengrabs of the scene, a test render, and light parameters?

[andeltoz]

Certainly.
Since I have a job delivery to do, on the weekend I am attaching the material with the requests you made.
I'll just attach the images and lighting data of the work that I have to deliver.

[burnin]

Or simply use native C4D Light, its falloff can be controlled and behaves as you set it.

[andeltoz]

Hello.
I studied a few things and found the solution. I think it is not the most orthodox, but the important thing is to have found the solution, don't you think? I use lumens and also reading some articles on the web about how the light behaves in Corona, I saw that the problem was the size of the light. I used too small a light size (1cm) which produces hard falloff. By increasing the size of the light (4 cm), with the same luminous flux, I obtained more nuanced falloff, as happens in reality. I am attaching the version with hard falloff, a photo taken in my bedroom (excuse the confusion) and the final version with the adjustments.
Is it the right solution or are there other things to keep in mind?

[philipbonum]

If you haven't tried it yet I would suggest trying to add different IES to your light. Light is usually a bit more nuanced than what a standard corona light can deliver

[burnin]

Ah, so to be clear, you were really looking for how to control shadow size, not light falloff/decay.
As mentioned by TomG, that's always physically correct (same) same using Corona's light source no matter what.

PS
For clarity sake, would be good to change OP title.

[andeltoz]

In Vray 3.6 / 3.7 (I don't know in Version 5), there is a value called "Shadow radius", which is done on purpose to check the problem I raised. Is there anything similar in Corona Render?
I still ask about the problem I raised, because I do not consider it correct to act on the size of the light to obtain the result I had in the images attached to my previous post.
Thank you

[romullus]

LOL, the size of the light source, and ratio of distance between light, obstacle and receiving surface, is exactly physically correct way to deal with your issue and not some artificial shadow modifier, which was invented at the times when computers were not powerful enough to calculate physically plausible light behaviour. If your model is close enough to the real thing and your light source has correct size and intensity, then you should get result that is very close to reality. No hacks are needed.

[andeltoz]

LOL, the size of the light source, and ratio of distance between light, obstacle and receiving surface, is exactly physically correct way to deal with your issue and not some artificial shadow modifier, which was invented at the times when computers were not powerful enough to calculate physically plausible light behaviour. If your model is close enough to the real thing and your light source has correct size and intensity, then you should get result that is very close to reality. No hacks are needed.

LOL. I am not sure I have reproduced reality so faithfully, but I think I have come close enough to have a result that does not correspond to what happens in reality. You probably haven't looked at the images well, otherwise you would agree with me that there is something wrong. Vray's was just an attempt to solve the problem, since the result is not real, but I am just a humble user of the software observing what is happening around him.

[burnin]

In case you've missed it...

Or simply use native C4D Light, its falloff can be controlled and behaves as you set it.

e.g. color ramp falloff linear decay