IES light power setting

[edonk]

I am having trouble adjusting the power of my IES lights in a scene. Doesnt matter what value I put in the "power" slot the output is always the same.
Is the power value over-ridden by the IES manufacturer data loaded into the IES slot?

[dkendig]

Re: IES light power setting

Power is in Lumens

http://www.spot3d.com/vray/help/150S...ght_params.htm

By default the power is set to 0, which means that it will use the IES file itself to determine the proper power. If you're not getting the results you like, you might want to try a different IES file. Power should only be changed for slight adjustments.

[edonk]

Re: IES light power setting

ok, thanks for the quick response Dkendig I'll try another IES file.

[diogodasilva@mac.com]

Re: IES light power setting

if you are using phys cam you should really crank it up .. go extreme.. I'm serious..

[dkendig]

Re: IES light power setting

not necessarily, it all depends on the ies files you use. Try getting some from various manufacturers, and see which ones you like best. Sylvanna, GE, Eclipse, etc. It helps to search for the term "photometric data" as well when searching for ies files.

[diogodasilva@mac.com]

Re: IES light power setting

By the way do you know of any tool to convert .LDT files to .IES? Many manufacturers use eulumndat.

[diogodasilva@mac.com]

Re: IES light power setting

Another question...

What is the unit used for the IES Light power parameter (lumens, candelas..)?

[fpedrogo]

Re: IES light power setting

What is the unit used for the IES Light power parameter (lumens, candelas..)?

Devin wrote

Power is in Lumens

http://www.spot3d.com/vray/help/150S...ght_params.htm

By default the power is set to 0, which means that it will use the IES file itself to determine the proper power. If you're not getting the results you like, you might want to try a different IES file. Power should only be changed for slight adjustments.

[diogodasilva@mac.com]

Re: IES light power setting

So you are saying one should get a brighter image by manipulating exposure settings on camera instead of overpowering the ies light?
This can be a bitch if you are dealing with environment lighting such as sky for example.. it would overexpose the shot...

any ideas?

[fpedrogo]

Re: IES light power setting

So you are saying one should get a brighter image by manipulating exposure settings on camera instead of overpowering the ies light?
This can be a bitch if you are dealing with environment lighting such as sky for example.. it would overexpose the shot...

You must setup first the light with the most contribution in the scene. Usually the sun and the physical camera. Then you could setup the artificial light as IES, rectangular, spotlights or omni lights. Remember that the physical camera control the exposure of every single light in the scene, so it is better to get a decent illumination just with the physical camera and then add the other light and adjust their multiplier or power to fit your style. I said style because every artist have their own style and workflow and all are good if they can get a decent render.
It is true that you have to increase very high the IES power to get your desired effect, the reason is because the Physical camera control the exposure of the IES light as well. If you don't use the physical camera, the default IES power should be enough.

The question that I was trying to answer was that the power of the IES is in Lumens.

Best

[dkendig]

Re: IES light power setting

some IES files are brighter than others also, so it all depends on the IES file you use too. Setting some ridiculous power setting is silly though. Just get IES files that provide the proper level of illumination. Try more than one company's IES files until you find one that suits your needs. If you set anything for the power value, you override the illumination information in the IES file, "power" isn't called "multiplier" for a reason. There are also tools out there that allow you to edit or create IES files, you might want to look in to those as well.

[diogodasilva@mac.com]

Re: IES light power setting

Could you attach an IES file as example?
Which doesnt need extreme values when using phys camera?

[dkendig]

Re: IES light power setting

here's an example of an ies light, completely default settings, no sun, physical camera is on.



The ies file is named: 80PAR-HIR-SP10_(27216).ies

It can be found on eclipselighting.com: http://genet.gelighting.com/LightPro...ESCATEGORYPAGE

Now keep in mind, this is just default physical camera settings. If you're doing an interior, and you're using an IES light that represents the photometric data of a light that should be used indoors, you probably want to adjust your physical camera's settings to adjust to the indoor environment. If you're doing an exterior render, then you want to be sure you have an IES file for an exterior light that is bright enough to compete with whatever sunlight you have in the scene. For example, the renders below were done with an IES light that has a much lower intensity:

Physical Camera ISO = 100
Physical Sun Enabled = True


Physical Camera ISO = 100
Physical Sun Enabled = False


Physical Camera ISO = 3200
Physical Sun Enabled = True


Physical Camera ISO = 3200
Physical Sun Enabled = False

[diogodasilva@mac.com]

Re: IES light power setting

I feel nomatter which ies file u use, the light power is always underrated. For example in real life, in the scene u set up would've been overexposed with an iso that high. And on vray it barely scratches... So you find yourself always having to compensate. Either camera or the light power setting.

Also, very often people use IES files for spot lamps, mr16, par, ar, ... The power of these is measured in candelas, not lumens.

[edonk]

Re: IES light power setting

I feel nomatter which ies file u use, the light power is always underrated. For example in real life, in the scene u set up would've been overexposed with an iso that high. And on vray it barely scratches... So you find yourself always having to compensate. Either camera or the light power setting.

Also, very often people use IES files for spot lamps, mr16, par, ar, ... The power of these is measured in candelas, not lumens.

Im not sure what is going on there then, I found it to be the complete opposite to what you describe. My IES lighting is too intense for my scenes and needs toning down...