Spot light beam angle and CoronaLight Directionality

[dsolod]

Hello,
Is it the linear dependence between the technical characteristic of the light source and CoronaLight parameter? Let's say setting the Directionality to 0,5 will be physically correct for 90 degrees beam angle?
Thanks

Dmitry

[maru]

Not sure if I understand your question correctly, but I would say that directionality 1 = 90 degrees beam (the light shoots straight from the light object's normals - like laser).

[burnin]

Area light directionality % with Corona 7daily for C4D
@ 1 fps

[dsolod]

Not sure if I understand your question correctly, but I would say that directionality 1 = 90 degrees beam (the light shoots straight from the light object's normals - like laser).

Hi Maru,
Let me re-phrase my question.
How should I adjust the Directionality parameter to match the Beam Angle of 60 degrees from the light's technical specification? Will it be (1-60/90)?
Thanks!

[burnin]

a bit clearer animation of
directionality VS angle
what you assume, doesn't coincide

[romullus]

@burnin, your angle is incorrect, it shows 90°, when actual angle is 180° It's also quite strange why in your example light beam never goes completely parallel at 0° Maybe it's because of your scene's setup?

[burnin]

Right, values are script-driven, so symmetry modifier makes total angle half size and I forgot to compensate. // tnx on notice :)

About 'strange' behavior @ 0° angle. It's natural. IIRC, there's no laser in Corona.

Maybe a bug? How's on Max?


 

To answer OP: "No, dependence isn't linear."
Also, gamma & quadratic function can be observed...

[romullus]

Maybe a bug? How's on Max?

Looks about the same in Max. Probably it's expected behaviour. As you noticed, Corona light is not a laser even at directionality being at full strength.

To answer OP: "No, dependence isn't linear."

I wonder what's the reason behind this? I always thought that it is linear. Maybe it would make more sense to have directionality expressed in angle, instead of 0-1 range? @Team?

[dsolod]

I would love to understand more about the Directionality parameter.

If it's not linear is it possible to correlate it with the light beam angle of the real lights?

I attached the scene with 3 IES lights taken from the Philips lighting website:
https://www.usa.lighting.philips.com/support/support/literature/photometric-data#led

My question is How to adjust the Corona lights to mimic the similar beam angles? Only by trials?
Any help will be appreciated

[dj_buckley]

I raised this issue (or similar) a while back https://forum.corona-renderer.com/index.php?topic=23208.0