Hello,
I want to understand the maths of the first test calculation I did in DiaLux Evo. I have an IES file . Let's say the location for a lantern at a height of 6 metres (and no other parameters). The height of the lantern itself is 0.292 according to the IES file. I did the calculation on a simple 5x5 metre floor surface under the lantern. I got values slightly different from the ones I calculated manually by myself. So, at point (0,0) (right under the luminaire) according to DiaLux it is 6,0 (see the screenshot - value chart). But I thought it should be 6,19.
I thought that for each point in 3D, we calculate its polar coordinate, then calculate the corresponding horizon/vertical angles, do a bilinear interpolation to get the Candela value - the intensity - and divide it by the square of the distance from the luminaire to the point. So I see that the luminaire is located at the physical centre, so I subtract its size/2 from its height (=5,854), the horizontal and vertical angles don't need to be interpolated, and that's it. I double-checked all my calculations, there shouldn't be error in them.
Is my mathematical interpretation of calculating the luminance at a point from the IES file correct or not?
If so, what parameters in DiaLux am I missing? I have set the Maintenace factor to 1.0. The floor height is 0.001. It looks like some additional factor is included in the calculation.
Michael L.
