IES vs HDRI lights

[Da_elf]

Naturally i was pissed off by the render times of ies lights. So i started to fool around with them and normal lights to see if i could fake it. I setup a spot light and an ies in the same location and had the spot turned off. i only used it as a camera point to look at the image the ies light made on the ground. this i saved as an hdri then i loaded it into the projector slot of the spot light.

IES light


Spot Light Multiplyer = 1 HDRI Multiplyer = 1


Spot Light Multiplyer = 2 HDRI Multiplyer = 1


Spot Light Multiplyer = 3 HDRI Multiplyer = 5


Spot Light Multiplyer = 1 HDRI Multipley = 40


So it seems the closer you get to looking like the IES light it seems you cant escape the render time. Best solution however was to use a lower light multiplyer and higher HDRI multiplyer

[kippu]

wow good test ....thanks

[pengo]

Hi Da_elf

thank s for the explanation

but could u suggest what do u mean for low value for a IES light source?

I never used them and so I don't know wich are high and low values for this kind of sources that I remember different from standard for intensity

thanks in advance

[vlado]

You would need inverse square falloff for the light, if you want to model an IES light source, too.

Best regards,
Vlado

[Da_elf]

yeah. my spot was using inverse square.

[Da_elf]

pengo...what did you mean by asking what i meant by low value for ies lights. i never said anything about low values.