Get Lux (light) value in a specific 3d Point of my drawing

[mike42]

Hi guys,

I have a 3d Drawing with very detailed light source descriptions. Is there any way I can measure a light intensity (in lux) in a specific point of my drawing?

[AONE_LED]

AutoCAD has no tool that reads lux at an arbitrary point, so you need a workaround. Use photometric lights (set LIGHTINGUNITS to 1 or 2, define lights by candela or lumens, ideally with an IES web file) and render with a photometric exposure setting. Pixel brightness in a render is only a visual indication, not a calibrated lux reading. For an actual value at a point, use the inverse square law, E = I x cos(theta) / d squared, taking the candela from the IES file in the direction of the point; measure at working height, normally 0.8 m for a desk or floor level for corridors. For a real design, export the luminaires to a dedicated lighting calculation program that outputs a lux grid on the working plane.