Exercise: Estimating forest area of county Göttingen based on digital landscape model (DLM) and administrative boundaries 1: 250 000
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== Use of digital topographic map 1:250 000 as web map service (WMS) == | == Use of digital topographic map 1:250 000 as web map service (WMS) == | ||
Digital topographische maps describe topographical objects of the landscape and relief of the earth's surface in raster format. | Digital topographische maps describe topographical objects of the landscape and relief of the earth's surface in raster format. | ||
| − | # Add an open WMS data sets. Click {{button|text=Add WMS Layer}}. {{mitem|text=Layers --> New}}. Fill in the connection details. Name: {{typed|text=WMS dtk250}}, URL: {{typed|text=<nowiki>http://sg.geodatenzentrum.de/wms_dtk250</nowiki>}}. Click {{button|text=Connect}}. Select Layer ID: {{typed|text= 01}}, Name: {{typed|text=dtk250}}. The topographic map 1:250 000 of Germany is loaded. Zoom out to a larger overview.[[Image:dtk_250_goe.png|250px|thumb|right| '''Figure A:''' Digital topographic map 1:250 000. Source: http://www.bkg.bund.de | + | # Add an open WMS data sets. Click {{button|text=Add WMS Layer}}. {{mitem|text=Layers --> New}}. Fill in the connection details. Name: {{typed|text=WMS dtk250}}, URL: {{typed|text=<nowiki>http://sg.geodatenzentrum.de/wms_dtk250</nowiki>}}. Click {{button|text=Connect}}. Select Layer ID: {{typed|text= 01}}, Name: {{typed|text=dtk250}}. The topographic map 1:250 000 of Germany is loaded (Fig. A). Zoom out to a larger overview.[[Image:dtk_250_goe.png|250px|thumb|right| '''Figure A:''' Digital topographic map 1:250 000. Source: http://www.bkg.bund.de |
© GeoBasis-DE / BKG 2016]] | © GeoBasis-DE / BKG 2016]] | ||
Revision as of 15:23, 4 July 2016
Since 2013 the federal government ogf Germany has published the ordinance to determine the conditions for use and provision of spatial data. A couple of spatial data products are provided free of charge for download or online use by Bundesamt für Kartographie und Geodäsie in Frankfurt (BKG)
Use of digital topographic map 1:250 000 as web map service (WMS)
Digital topographische maps describe topographical objects of the landscape and relief of the earth's surface in raster format.
- Add an open WMS data sets. Click Add WMS Layer. Layers --> New. Fill in the connection details. Name: WMS dtk250, URL: http://sg.geodatenzentrum.de/wms_dtk250. Click Connect. Select Layer ID: 01, Name: dtk250. The topographic map 1:250 000 of Germany is loaded (Fig. A). Zoom out to a larger overview.
Figure A: Digital topographic map 1:250 000. Source: http://www.bkg.bund.de © GeoBasis-DE / BKG 2016
Use of digital landscape model and administrative boundaries 1:250 000 as web feature service (WFS)
- Click Add WFS Layer and Server connections New. Fill connection details. Name: WFS DLM250 BKG, URL: http://sg.geodatenzentrum.de/wms_dlm250. Connect. Mark the row with TITLE = OBJART_43002_f01 (Forest). Add. Forest area objects of Germany are downloaded as vector polygons. Click Close and the polygons are displayed in the viewer. The object codes can be found in the docs in german http://sg.geodatenzentrum.de/web_download/dlm/dlm250-aaa/dlm250-aaa.pdf and english: http://www.geodatenzentrum.de/docpdf/dlm250_eng.pdf. Examples for modelling classes of the object Nr. 43002 are:
- Waldverjüngungs-, Neuanpflanzungsfläche http://www.geodatenzentrum.de/geodaten/modell_adv.disp_pdf?gdz_sort_id=575
- Waldbestattungsfläche http://www.geodatenzentrum.de/geodaten/modell_adv.disp_pdf?gdz_sort_id=572
- Laubholz http://www.geodatenzentrum.de/geodaten/modell_adv.disp_pdf?gdz_sort_id=113
- Nadelholz http://www.geodatenzentrum.de/geodaten/modell_adv.disp_pdf?gdz_sort_id=114
- Laubholz und Nadelholz http://www.geodatenzentrum.de/geodaten/modell_adv.disp_pdf?gdz_sort_id=115
- Click Add WFS Layer and Server connections New. Fill connection details. Name: WFS VG250 BKG, URL: http://sg.geodatenzentrum.de/wfs_vg250. Connect. Mark the row with TITLE = Kreis. Add. All county boundaries of Germany are downloaded as vector polygons. Click Close and the polygons are displayed in the viewer. Open the attribute table of layer Kreis. Select features using expression. Type the epression "GEN" = 'Göttingen'. Click Move selection to top. The county Göttingen is now selected. Mark layer Kreis in the layer panel. Save as ... Type path and file name and check the box Save only selected features. OK.
Calculating forest area of County Göttingen
- Clip forest area of Germany with county area of Göttingen. Vector --> Geoprocessing Tools --> Clip. Input vector layer = OBJART_43002_f
Clip layer = Landkreis Göttingen. Output shapefile = OBJART_43002_f_clip. OK.
- Calculate area and perimeter for the clipped forest polygons. Vector --> Geometry Tools --> Export/Add Geometry Columns.
- Calculate the sum of the column AREA in the OBJART_43002_f_clip layer. Vector --> Analysis Tools --> Basic Statistics. Divide the result by the total county area given in column Shape_area of the attribute table of layer Landkreis Göttingen. What is the percentage of forest area in county Göttingen?
