I am new to GIS and I have to do the following:

  1. I have a GeoTIFF raster file of a map with some features like clouds and water bodies. It is a satellite image. My images are taken from a snapshot of https://worldview.earthdata.nasa.gov/ which gives me a GeoTIFF file.
  2. I have to encircle a particular feature like a particular water body or some area of the cloud coverage.
  3. The area I encircle would give me the coordinates in (lon/lat) of the area so that I can use the coordinates in programming contour plots.
  4. It is better if I can get the coordinates as a CSV file.

What I have tried so far:

  1. I added the raster TIFF image.
  2. Used the New Shapefile Layer Icon to create a disastrous polygon to encircle a particular area.
  3. A shapefile (vector layer) gets added on top of the raster map.
  4. I tried exporting the geometry coordinates to a CSV file, but was unsuccessful.
  5. I tried the MMQGIS plugin and export the shp coordinates to a CSV file, but it was of no avail, because I got only the four boundary coordinates.

Is there any better way in getting around this stuff? Especially in drawing a freeform vector and getting the coordinates of the encircled area.

  • with QGIS2 you could use Map Corners Coordinates Plugin ctu-geoforall-lab.github.io/qgis-map-coords-plugin - just zoom in to particular region you are interested in and use the plugin to export the coordinates of the map windows extent to a text file. – Juhele Jul 21 '19 at 12:15
  • Thanks a lot, but I am looking for an areal extent rather than a window. I have QGIS3 so this won't work. – cwanderroycbooks Jul 21 '19 at 12:21

Export to CSV

You should be able to export the features as CSV in QGIS. Please try again with the following options: 1. for the Geometry type, select Polygon 2. Under Layer Options, GEOMETRY, select AS_WKT

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The output should have the geometry information.

Export only the bounding box

If you just want the bounding box of those areas you draw, you can go to the Processing Toolbox and use the Bounding boxes algorithm to create the minimal rectangular areas around your features. Export the result as CSV, using the above options.

Export only the center

If you only need the center, you can use the Centroids algorithm in the Processing Toolbox. Export the result as CSV, using the above options.

  • I tried this, by rightclicking the polygon shapefile and exporting it. The output file had only two columns, namely the shapefile name, and nothing else. – cwanderroycbooks Jul 21 '19 at 12:37
  • But have you selected AS_WKT for the geometry type? – jgrocha Jul 21 '19 at 12:38
  • By default, the geometry is discarded if you do not change the GEOMETRY to AS_WKT. – jgrocha Jul 21 '19 at 12:40
  • I selected the WKT option but the same result. – cwanderroycbooks Jul 21 '19 at 15:14

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