Exercise: Mapping storm damaged forest areas – AWF-Wiki
Mapping of forest damages caused by storms using visual interpretation of very high resolution digital ortho photos (DOP) needs clear definitions and characteristics which are usually documented as interpretation key. Here, clearings are defined with a minimum area = 0.2ha, minimum width = 20m, and a tree crown cover <, 10%. Characteristics of windthrow areas depend on the time between storm events and the availabiltiy of optical remote sensing images but also on the status and progress of logging and clearing operations at the time of image acquisition. Typical characteristics for recognizing storm damages are: horizontal complete trees with root plates, root plates, stumps with fresh cross section, piles of logs for storage / skidding, piles of branches, skid roads and tracks, no or few ground vegetation. Load and display German Geoadata using QGIS 2.4 following the Exercise: Displaying German Geobasis data (GBD) or load the saved project file .GBDatadisplay_gbd.qgs where the project coordinate reference system (CRS) is set to ETRS89/UTM32N (EPSG:25832). Web map services (WMS) like Google Maps, Bing Maps, Yahoo Maps and OpenStreemap use a special projected coordinate reference system called ‘Pseudo Mercator’ or ‘Web Mercator’. A new Layer Google Maps is loaded into the layers window. The project CRS is automatically set to WGS84/Pseudo Mercator (EPSG:3857). Check the actual project CRS Project –>, Project Properties –>, CRS, the checkbox ‘on the fly’ transformation is switched on. The EPSG code of the actual project CRS is also displayed on the lower right below the viewer. Source.