Revision as of 08:33, 4 December 2020

Non-statistical based selection

Prepare sources for reference data collection

1. Load a LUC classification map of the Urban European Atlas for Göttingen in vector format. (Loading vector data)
2. Load Digital aerial Ortho Photos (DOP) published as "Google Satellite". (Load a WMS-Layer).
3. Load a multiband (B2,B3,B4,B5,B6,B7,B8,B8A,B11,B12) Sentinel-2 satellite image and display a false color composite (RGB = B8,B11,B4 =7,9,3). (Changing Raster Layer Style)
4. Right click on the satellite image file name in Layers window. Layer CRS --> Set Project CRS from Layer.

Create a new vector layer

1. Select Layer --> Create Layer --> New Geopackage Layer.
2. Define path and file name.
   • As Geometry type, select Polygon.
   • Click the Specify CRS button and select the Project CRS, e.g.: WGS84 / UTM32N (EPSG:32632).
   • Adding an additional column in the attibute table:
     • For the attribute's name type C_ID into the Name field of the New attribute section.
     • Select Whole number (integer) as data type.
     • Confirm with Add to Fields List. OK.

400px

Configure vector digitizing

1. Select Project --> Snapping options.
2. Activate Snapping clicking on .
3. Change the dropdown list All Layers to Advanced Configuration
4. Activate the checkbox of a vector layer for which you wish to configure snapping.
5. Click in the Type column of the vector layer. In the dropdown list activate Vertex and Segment.
6. Choose Units meters.
7. Select the snapping Tolerance 2(meters).
8. Activate the checkbox Avoid overlap.
9. Activate Topological Editing and Snapping on Intersection

Start digitizing

1. Mark the new vector file in the Layers window. Start the edit mode by clicking the Toggle editing button .
2. Let's start with land cover class Water. Use the European Urban Atlas to find water bodies. Zoom in to a lake.
3. Click Add feature to start digitizing. Start drawing polygons with left click. Finish the geometry by right-clicking.
4. Enter the LUC class in the C_ID field. OK

You may always delete a polygon by simply clicking Cancel in the attributes dialogue, or by selecting it and deleting with the Delete selected button. Save your edits by clicking at times on . Finish the edit mode by clicking Toggle editing .