Any hints to extract illuminance/brightness values on surfaces?

Hello UE gurus,

I hope you can help me on this stubborn issue, I am using UE to create a daylight visualization tool, where physical accuracy of lighting is crucial. I was wondering if there is away to visualize the luminous environment in false color, based on a legend of lux values as the image attached.


I have tried relying on Histogram (EV) visualization to give the same effect as shown below, but it is not based on lux and the EV range it gives doesn’t seem to give true illuminance values.

Any solutions or hints to create such effect based on illuminance/brightness/luminosity values? much appreciated!