Led linear ies file uncorrect displayed

[giobuttu]

With the advent of LEDs there has been a strong development of linear lighting fixtures (LED bars) with different optics, symmetrical, asymmetrical, wallwasher, etc..
In the IES file are reported both the information of the light distribution but also the dimensions of the emitting surface. This last information could be necessary for the correct visualization of the light distribution in Vray.

Now It seem the light distribution nont working well. Is it a bug or I'm wrong becouse exist other way to do tath?

If this is a bug I think must be fixed, soo, because the simulations are wrong and misleading.

Attached you will find:
- photometric file used for the tests (provided by the manufacturer of luminaires)
- Simulation image made with Dialux Evo in which you can see the correct light distribution along the entire linear surface of the LED bar in order to compare the Vray simulation
- Simulation image in Vray of my project in which it is evident that the photometry ies is distributed only in a spot way in the insertion point.

Thanks in advance

[konstantin_chaos]

Hi giobuttu,

The option that enables area IES lights in Rhino is currently hidden.
We can easily expose it in one of the upcoming updates.

In the meantime you can enable it for all IES lights in your scene with the following Python script:

import rhinoscriptsyntax as rs

vray = rs.GetPlugInObject("V-Ray for Rhino")
iesLights = vray.Scene().PluginsByClass("LightIES", False)
for x in iesLights:
    x.Param("soft_shadows").Value = 2

There are 2 issues that you will still experience:

1. There is no shape gizmo in the viewport making it hard to orient the light.
2. Some areas of the light contribution are cut out in a strange way. This has been logged in our bug-tracking system as VRW-3110

Thanks for bringing this to our attention!

Konstantin

[giobuttu]

Thanks for your continuos improvments.

[giobuttu]

konstantin_chaos

I downloaded the last Vray for Rhinceros 7 Version 5.20.04 (with last update of Rhino 7 SR14 2022-1-10). It seems that enamble ies soft shadows is hidden again. In addition the python script you gave us last year doesn't work, please see attached image.
I'm not python expert so can you kindly correct the script to allow us to better use the soft shadow option.



Thanks in advance

[nikolay.bakalov]

Hi
In the latest release (update 2.3) the PluginsByClass method was renamed to PluginsByType
Please update your script like this:

import rhVRay as vray

for iesLight in vray.Scene.PluginsByType("LightIES", False):
    iesLight.soft_shadows = 2

[giobuttu]

Hi,
Thanks a lot for your reply. I think it very is important to make visible this option in ies file options.

[oconv]

That's interesting, since we do a lot a light planning using vray.
However, I'm a bit confused about the benefit of the script.

When rendering with:
shape: from IES file with iesLight.soft_shadows = 0
I get same result as with:
shape: point with iesLight.soft_shadows = 2
but
shape: from IES file with iesLight.soft_shadows = 2
gives the wrong point source result.

So what is the reason/benefit for iesLight.soft_shadows = 2?
Why does the shadow qualitiy affect the light shape?

-g.

[konstantin_chaos]

Hi oconv,

iesLight.soft_shadows parameter determines what the 'physical' light shape is going to be considered for
0 - The light is going to be emitted from a point. The shadows are going to be sharp
1 - The light is going to be emitted from a point. The shadows are going to be soft based on the light physical shape
2 - The light is emitted from the physical light shape. The shadows are going to be soft based on the light physical shape

What you've shown is actually a little strange.
I'll look into it in more details and get back to you.
As a reference I've logged this in our internal bug-tracking system - WEBUI-6157.

Konstantin