Sky Patch Position _ Sky Luminance Distribution Calculation


Dear All,

Thank you for your great contribution in the field.

I am in a validation stage of my model using a solar simulator. I need to define the position of a sky patch/element at a specific hour. According to ISO 15469:2004,

"The position of an arbitrary sky element is defined by its zenith angle, Z, and by the azimuth difference between the element and the sun, [α - αs]. If Zs is the zenith angle of the sun, the angular distance between the element and the sun is:

x=arccos⁡(cosZscosZ+sinZssinZ*cos⁡[ α-αs]


By using LadyBug_SunPath component we can get the azimuth and the altitude/elevation of the sun. And by LadyBug_SkyDome component we can visualize the sky patches for certain hour, however, I could not find a way to get the exact value of the azimuth or the altitude of the sky patch for that hour so I can define the sky position by the above equation.

Anyone have an idea to find either the azimuth or the altitude of the sky patch, either theoretically by calculations or by Ladybug tools, please?

Your support is highly appreciated.

Thank you,


I guess that taking the skyPatchesCenPts output from the LB_SkyDome component you can get both altitude and azimuth from the center of the dome.
Hope that makes sense.


Hi Abraham,

Thank you for your prompt reply. I really appreciate it.
Yes, I agree, this is a smart straightforward way to determine its position.