Findclouds Manual 31
accessible, the dialogue will only use a list of files and fetch the images from their original place. To
achieve this, "Copy Images" must be deactivated.
"Copy Images'' activated
When older images will be deleted or moved to an archive data
backup, the dialogue can copy Clear Sky Images to an individual directory "csl", to keep them
accessible for evaluations. To achieve this, "Copy Images" must be activated.
The state of "Copy Images" depends on existing "csl" directory inside of the Cloudcam directory. It
can be different for different Cloudcams. It is not possible to undo a new state "Copy Images" by
using button [Cancel], these changes will be processed at once.
When activating "Copy Images", the software will create a "csl" directory for the particular
Cloudcam and will copy all images of "ClearSkyLibrary.txt" to this directory. After that the software
will fetch Clear Sky Images only out of this directory.
When deactivating "Copy Images", the "csl" directory will be deleted and included images will be
lost. After that the software will fetch Clear Sky Images from their original position.
Furthermore the Findclouds software won't track manual changes of "csl" content. When there is
no "ClearSkyLibrary.txt", but a "csl" directory, the software will rebuild the "ClearSkyLibrary.txt"
using the content of "csl" directory.
[Cancel] / [OK]
There are the common buttons [Ok] and [Cancel]. The button [Ok] will save
changes of "ClearSkyLibrary.txt" and "ClearSkyJunk.txt" and the button [Cancel] will discard them.
2.10 Sunpixel Evaluation
One important information the software should provide, is visibility of the sun itself. To achieve this,
the sky image will be changed into a gray scale intensity image. Using this image, it is easy to
recognise overexposed pixel which are caused by the sun and its surrounding field.
The first version of this software checks for overexposed pixel and when there are some, it states
sun as visible. But this caused a lot of false positives and stated sun as visible, even when there
was just a bright spot in a completely clouded sky. This is caused especially by automatic choice of
exposure, because a completely clouded sky will raise exposure time so much, that such a spot
overexposes the same way as a directly visible sun. A simple and obvious solution of this problem
would be a fixed exposure time, to set a defined level for recognition of sunpixel. But this often
would cause an additional image and also won't recognise, when sun shines through a small gap
