IES Lighting.........setting nowhere near correct

[philip kelly]

I am using IES files in a model to uplight a large canopy externally.
I have set everything correctly.
But is not correct, it's very obviously not correct.

So why do IES files not give the correct render output
Is the scale settings in max. i use Meters, i don't use Auto exposure.

So what the solution?

[vladimir_krastev]

Hi, thanks for posting. Please send your scene for review. You can do that here or though the support contact form. Please add a link to this thread for faster tracking.

[philip kelly]

Thank you.
I have submitted a folder with everything in it to get to the bottom of the issue.

[philip kelly]

Good morning.
Any update on this problem.
I am the only one who has an issue with an external light with ies files?
Some one else must have come across this issue before?
I would appreciate the help.

Regards

Phil

[philip kelly]

I have been reading through the forums.

Am I right in saying that 90 percent of IES files are not supported?

They do not give the correct intensity in the render.

Can someone for Chaos Clarify this please.?

[vladimir_krastev]

Hi, VRayIES is more oriented towards photorealistic look of the light in the rendered image and not especially for lighting analysis. This should not lead to significantly big differences that are visible with a naked eye though. We will review your scene and get back to you.

[philip kelly]

Thank you very much. It's appreciated.

philip

[Joelaff]

Just curious, does increasing the multiplier get the light to look the way you want it? It sounds like you are after accurate lighting representation based in real world data (like for architecture) rather than just a nice visual look.

I am in VFX which is a different ball of wax, but curious about your experience.

[philip kelly]

Arch Viz, for a major project, and the light has to be accurate for the presentation to give the go ahead.
It looks like the shape of the light is correct but the intensity is not right , and I don't think it can be said to accurate when you look at the render you know.

[philip kelly]

Any official result on the file I sent last Thursday?
Were my settings wrong .................

[vladimir_krastev]

Hi, I reviewed your scene. You did not have V-Ray materials applied in it. Here is the result after applying a default V-Ray material and resetting your render settings to default.

From my view this image looks correct. Could you confirm and if not please give us more details about what is wrong with it? A reference image would be best.

[philip kelly]

Thank you
The material I had on it was Vray i am sure, but it was the Vray material Plaster white smooth 300cm ...from the library.
But they would not have made a big difference to be honest.
The brightness is brighter than I got from rendering in both Corona and Vray.
But It is what it is.
The Image the engineers sent me I have sent to you , and they had brought it in to Unreal and gotten a much brighter image , but with Bloom and Glare.etc.
Anyway, thank you, I appreciate the work you have done.
I personally thought it would be brighter for a canopy up light, Maybe more than 7 units are needed and also bigger and stronger lighting is required.

But My conclusion form this exercise is that "ies files" in both Corona and Vray, can give the shape of the light, but not the brightness accurately.

This is by no means a negative comment, just a fact that has to be taken on board for future work.
Thank you again.
Support as always is excellent.

[Vizioen]

I remember back in the day when I still had a collection of 10.000 + IES lights, that I got from the website of the manufacturers, they NEVER had the correct brightness and I always had to crank up the intensity by a lot.

[vlado]

In the VRayIES light, there is a setting called "override intensity"; the default is "rescale" which means that the IES light will use the prescribed emission value in the IES file. However we found out that it is often wrong, so we introduced the "replace" mode where V-Ray would recalibrate the intensity of the light to produce exactly the intensity specified by the user.

Note that when using physical light units you also need to use physically accurate camera exposure values on order to get a correct result.




Best regards,
Vlado

[philip kelly]

Vlado, thank you.for answering this issue personally. Appreciated.

Philip