WMD (WILLIAM Meteo Database)

WILLIAM Meteo Database

Introduction of project WILLIAM:

Wide-field imaging is a popular way of monitoring the night sky to get a real-time view of current weather conditions. The project WILLIAM (Wide-field all-sky image analyzing monitoring system) was created on demand to provide autonomous control of the telescope and observatory dome. The main goal of this project was to develop a low-cost wide-field and high resolution camera system, whose image data is can be archived for later analysis. One of the options of evaluating current weather conditions from the captured image data is to count visible stellar objects. To work properly, the system must be calibrated to a minimum number of visible stellar objects. If actual image data includes less detected stellar objects than it is calibrated for, the system evaluates the possible occurrence of clouds or rain. Such conditions are then interpreted as inappropriate for using a telescope. Thus the observatory dome stays closed or is going to be closed. The detection of clouds can also be carried out directly in the vicinity to mid-IR. The advantage of IR-based systems is the possibility to detect clouds under any conditions. However, these systems require very complicated and expensive optics and detectors.

Dataset

Original and support test image data for the research letter "Assessing Cloud Segmentation in the Chromacity Diagram of All-Sky Images".

Data for this database are provided from the WILLIAM system located in Jarošov nad Nežárkou (South Bohemia, GPS 49.185N, 15.072E). 

Images are stored in the original raw NIKON format NEF in the separate WMD_NEF.zip file. Support images with clustered data in LAB color space and XYZ color space are located in the LAB_clusters.zip and XYZ_clusters.zip files. Cloud annotation (attributes) for LAB and XYZ clustering is present within the WMD.xlsx file. 

attributes 

Image Number

ID (name of image file)

Day image number (number of image in a day of capturing)

Date (date of image capturing)

Time (time of capturing)

Cluster with sun (index of the cluster from the support cluster image files that includes the sun - only if the sun was present)

Clear sky (index of one cluster or several clusters from the support cluster image files that include clear sky part of image)

Cumulus (index of one cluster or several clusters from the support cluster image files that include cumulus cloud part of image)

Stratus (index of one cluster or several clusters from the support cluster image files that include stratus cloud part of image)

Stratocumulus (index of one cluster or several clusters from the support cluster image files that stratocumulus cloud part of image)

Nimbostratus (index of one cluster or several clusters from the support cluster image files that include nimbostratus cloud part of image)

Altocumulus (index of one cluster or several clusters from the support cluster image files that include altocumulus cloud part of image)

Altostratus (index of one cluster or several clusters from the support cluster image files that include altostratus cloud part of image)

Cumulonimbus (index of one cluster or several clusters from the support cluster image files that include cumulonimbus cloud part of image)

cirrocumulus (index of one cluster or several clusters from the support cluster image files that include Cirrocumulus cloud part of image)

Cirrostratus (index of one cluster or several clusters from the support cluster image files that include cirrostratus cloud part of image)

Cirrus (index of one cluster or several clusters from the support cluster image files that include cirrus cloud part of image)

Edges (index of the cluster that includes masked edges of the image)

Rain (values 0 or 1 if the rain was present)

Cloud groups (main cloud classification groups)

1. high-level clouds (index of one cluster or several clusters from the support cluster image files that include high-level clouds in the image)

2. low-level (cumulus type) clouds (index of one cluster or several clusters from the support cluster image files that include low-level clouds in the image)

3. rain clouds (index of one cluster or several clusters from the support cluster image files that include rainy clouds in the image)

4. clear sky (index of one cluster or several clusters from the support cluster image files that include clear sky in the image)

Time distance from solar noon (in hours)

Time distance from Sunset or Sunrise (in hours)

Sun elevation (in degrees)

Note: The classification of the exact cloud class within the all-sky image is mainly tentative. The cloud group division served for classification purposes. 

The WMD.xlsx file consists of two separate clustering annotations in LAB and XYZ colour spaces. The file also includes the EXIF data infromation of each image.