The tregenzaskytype function determines the CIE general standard sky type for a given luminance distribution of a Tregenza hemisphere. Contrary to Tregneza’s method described in “Analysing sky luminance scans to obtain frequency distributions of CIE Standard General Skies“, the luminance distribution is normalized with the zenith luminance.
Usage:
[sky,RMS] = tregenzaskytype(L,sunaz,sunel,mode)
Where:
| Parameter | Description |
sky | Returns the best fitting CIE standard general sky as in CIE S 011, determined with Tregenza method. |
RMS | Returns the Root Mean Square deviation from the best fitting CIE standard general sky. |
L | Defines the Tregenza hemisphere luminance distribution. |
sunaz | Defines the sun azimuth angle \alpha_S. |
sunel | Defines the sun elevation angle \gamma_S. |
mode | Defines the luminance determination mode of the reference data: ’center’ default: uses the patch center point angles for luminance determination. ’mean’ uses the mean luminance of the four patch corner luminances as suggested by Tregenza. |
Examples
Determine CIE skytype at \alpha_S = 166\degree and \gamma_S = 33\degree:
L = ciesky(12,166,33); [sky,RMS] = tregenzaskytype(L,166,33)
See also: ciesky
Result:
sky = 12 RMS = 0
Determine CIE skytype at \alpha_S = 166\degree and \gamma_S = 33\degree with ‘mean’ method:
L = ciesky(12,166,33); [sky,RMS] = tregenzaskytype(L,166,33,'mean')
See also: ciesky
Result:
sky = 12 RMS = 0.2285
Note: the differences to reference sky modell in terms of RMS are due to the different determination method ‘mean’.
References