VRay ies lights and soft shadows

[GLASS-CANVAS]

Hi Vlado,

I notice in the latest service pack that VRay ies lights now have some support for using the light shape to determine the shadows. What would be really nice would be the optional override ability to change the size of the light casting shape like you can with spherical lights. Right now even if I ask the light to use the shape to affect shadows they seem to stay sharp. I suspect this is something to do with the geometry described in the ies file. It would be great to have total control over how soft you want the shadows to be on an ies light

[leehumphries]

Dont know if this helps or is old news now, but from reading a few years ago someone came along with the idea of changing the IES file in text editor - taking the - (minus) out gives me soft shadows

Any help?

[paolo242]

I don't remember who wrote this...

Here's the text from a standard Erco IES file (up to the point that's important for this example):

IESNA:LM-63-2002
[TEST] U100000_0
[TESTLAB] ERCO Leuchten GmbH
[ISSUEDATE] 20-11-2007
[MANUFAC] ERCO Leuchten GmbH
[LUMCAT] 22405023
[LUMINAIRE] LC Downlight
[LAMPCAT] MRC16 50W 10°
TILT=NONE
1 900 1 19 1 1 2 -0.051 -0.051 0

The important values are the last 4 (2 -0.051 -0.051 0)

The first of these specifies units (1 is feet, 2 is meters)
The remaining three values specify the dimensions of the light in said units as width, length and height, respectively.
If you change these values you give the light proper dimensions and VRay will render correct area shadows. I usually change the negative values to positive and let it be, but some of these might be pretty small, then I just make the light bigger till I get the effect I need.

I hope it will help you...
Paolo

[GLASS-CANVAS]

Well well, that worked a treat, thanks Paolo!

Would be great to have this easily accessible from the VRay ies light rollout

[Deflaminis]

Great thread!

[vlado]

We have already added the possibility to change the IES light shape for one of the next updates.

Best regards,
Vlado

[Wobi]

We have already added the possibility to change the IES light shape for one of the next updates.

Why not add a ies-editor right into the ies ui? this would be sooooooooo awesome. and if it would work in rt too....*just dreaming*

[voltron7]

Why not add a ies-editor right into the ies ui? this would be sooooooooo awesome. and if it would work in rt too....*just dreaming*

Ooooh, that sounds good here

[GLASS-CANVAS]

Thanks for the update, Vlado. One thing I have been meaning to ask for a while now is can we have a 'store with irradiance map' option on ies lights please?

[Dschaga]

Changing the shape of the ies photometric web?
It wouldn't make any sense if your client later wants a fixture with this kind of lightdistribution - you will render an image which can't be reproduced in realitiy - take care!

..but it would make sense to add a default maintaince factors to the light, which is in reality a comon parameter in lighting design and results in a longer lifecycle of the lamp but less poweroutput. a typical Maintaince Factor is 0.67.