Findclouds Manual 22
fisheye area.
The
zenith angle
starts with 0° at center and goes to 90° at red borderline, so a zenith angle of
90° would evaluate the whole image. But the zenith angle is restricted to 85°, because the plane
projection of the image works with the mathematical tangent, so larger angles will approach infinity
and prevent the image from being evaluable. For use of CDOC algorithm even a largest zenith
angle of 70° is recommended for best evaluation.
roller "Center":
The roller "Zenith" or the input field can be used to define a reduced zenith angle,
shown by the pink circle. In the final calculation of cloudiness the software will only evaluate
cloudiness inside of this circle.
At this point all necessary adjustments are done and the dialog should be left by using [Ok] button
for saving.
[Choose Photo]
can be used to load another photo for comparison, e.g. to control match of sun
position.
[Zenith]
will switch back to adjustment of offset angle and show not equalised photo without field
of view circle.
2.7.4 Input of Horizon
This is the configuration
window for input of horizon,
shown by the green line with
supporting points. This view
uses the projected image, to
get a better match of input to
real values of horizon line.
Also this way the final mask
used for evaluation will fit
exactly to the projection of
images. But the listed values
of elevation most likely will
differ from outdoor
measured values, because
graphical centring and equalisation are not high-precision.
We recommend to do horizon input, after all other calibrations had been done, because changing
