IES Profiles showing incorrect lumen intensity

Hi ,
I am noticing that when I import IES Profiles in UE, the lumens for the uasset don’t match the lumens in the raw IES file. Could anyone provide some insight as to why this might be the case?

render settings are attached for context. I am not sure if using extended luminous range is interfering with this

Just a blind guess: AFAIK Unreal’s base light unit is Candelas so my guess is that the “Brightness” field in the tooltip is converting Lumens to Candelas.

Yes, the brightness value is the converted candela, but not because it’s Unreal’s base unit, but because IES Profiles represent light intensity per angle which is represented by candelas, not lumens.

The information within the profile can vary a lot. You might see absolute lumens, max candelas, the beam angle, etc., but sometimes they might not have anything at all and the IES loader has to find the first value in the samples which ends up being the candela value.

The light from the profile has been discontinued and the spec sheets are limited, but the absolute lumens in the profile converted to candelas comes out to be about a 103° output which isn’t unreasonable for this type of light and it fits within the IV distribution shape the profile says it uses.

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