Question about IES lights

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polygonmode
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Question about IES lights

Post by polygonmode » Wed Oct 09, 2019 12:34 am

Hello indigo-community and developers,

after a really long period of absence, I am thinking about coming back to Indigo.
I just played with the current trial-version of indigo. There is a lot happened since version 2!

I remembered this forum as a really helpful and I can see, the old "greybeards" are still on board.

Maybe you guys can help me.

During my tests, I encountered a problem with IES-files. In the renderings, I attached, are 3 different IES-files from iGuzzini (https://www.iguzzini.com/). As you can see, they are all nearly the same width.
But they should have noticeable differences in width.

The two lights on the left (number 1) should be 34cm, the two in the middle (number 2) 64cm and the last two on the right side (number 3) 127cm.

So, what is the problem? Is it a generall problem? Is it possible, the IES-files have problems?
The documentation says, that indigo is capable of "just" rendering IES-files below a vertical angle of 90 degrees (https://www.indigorenderer.com/document ... ies-lights) Could this be a reason?

Don´t get me wrong, I am really impressed with the quality and the fact that it works somehow.
I tested the IES-files with Cinema 4D and they look really wrong.

I would be very happy to have some clarity on this topic because I want to use Indigo for special jobs, there correct lighting is absolutely needed and I see Indigo as the weapon of choice for these jobs.

Thanks in advance,
Carsten
Attachments
IES.zip
here you can find the IES-files, I used
(4.48 KiB) Downloaded 2 times
191008_IES_indigo.jpg
test rendering of IES-files with indigo
191008_IES_C4D.jpg
test rendering of the same files in C4D
check my site: www.polygonmode.com

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Zom-B
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Re: Question about IES lights

Post by Zom-B » Wed Oct 09, 2019 1:21 am

Hey polygonmode, nice to see you giving Indigo another try after all these years, welcome back!

For IES lights try using only a single 1 triangle emitter, since each triangle of the emitting mesh starts emitting its own IES...
Maybe just share your C4D scene and IES file so I can have a better look into your setup :)
polygonmanufaktur.de

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polygonmode
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Re: Question about IES lights

Post by polygonmode » Wed Oct 09, 2019 2:18 am

Hey Zom-B,

thank you very much for your fast reply!

You will find the .c4d file and the IES-files attached to this post.

To avoid any confusion:

I am happy with the characteristic of the light.
In the test rendering in the original post, I have 3 versions of lights.
Each version is also rotated by 90 degrees to see the other side of the light.

The problem is: they should have a different width, increasing to the right.

Here is the link to the products and I also attached screenshots where you can see, which type of light I used.

https://www.iguzzini.com/linealuce-surface/
screenshot_light_1and2.PNG
version 1 and 2 of the lights
screenshot_light_3.PNG
version 3 of the lights

Carsten
Attachments
investigation_indigo_ies-files.zip
c4d file with the ies-files
(69.75 KiB) Downloaded 2 times
check my site: www.polygonmode.com

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Zom-B
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Re: Question about IES lights

Post by Zom-B » Wed Oct 09, 2019 8:00 am

Hey polygonmode,

in my understanding of IES it is a purly 2 dimensional information that get extruded like in a Lathe Nurbs.
Therefore there shouldn't be any "other side of the light...

I attached my way to work with IES (and light in general): via material Emitter and a mesh you put it on.
Your way can "stretch" the IES by having multiple polygons (via a plane emitter).
If you have the feeling in a scene a IES does render very noisy compared to other bigger light sources, try to raise the "Emission sampling Factor" (in the Base Emission Setting). It does prioritize this light source further against others and allows it to grab more GPU/CPU cycles for calculation :)
Attachments
testfile_ies.png
IES_TEST.zip
(96.77 KiB) Downloaded 6 times
polygonmanufaktur.de

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Re: Question about IES lights

Post by pixie » Wed Oct 09, 2019 9:14 am

you've got quite a sexy way to deal with ies Zom-b! xD

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polygonmode
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Re: Question about IES lights

Post by polygonmode » Thu Oct 10, 2019 10:19 pm

Hey Zom-B,

I really thank you for your afford, you put into my question.

I am afraid, I was not able to explain my problem/question correctly.
So let me explain my problem in a different way.

Is it possible to use IES-files which are simulating a rectangular light-source, like an area light?
The lights I have to use look like this:
linealuce_HC_1280.jpg
light have too use linealuce from iGuzzini
These lights have a light beam like this:
light_beam.PNG
light beam of linealuce
These lights have different sizes, they vary in length between 61cm and 150cm. You can find them in the attached zip.

Thanks to Zom-B and his workflow, I made some progress.
I used an emitting null_material, applied to some polygons with the corresponding dimensions (61cmx5cm and 150cmx5cm).

This seems to work. as you can see here:
191010_screenshot_indigo.PNG


But I am not really sure if everything is correct in terms of energy, which is emitted.
The problem is, the light-setup has to be correct in terms of light-contribution and not just the look of the lights. That's why I am a bit nervous about how to handle these IES-files.

A good day to all of you!
Attachments
IES.zip
IES-files of the lights i have to use
(18.93 KiB) Downloaded 2 times
check my site: www.polygonmode.com

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