geocoding maps from articles

Topic: Geocoding maps from articles

By M. Neteler, FEM-PGIS: http://gis.cri.fmach.it/

PostGISomics

First step: Scanning the map or copying it from a PDF article

Copy map to file (PNG format)

Second step: Download and install a free GIS – Quantum QGIS

http://www.qgis.org

- Set LatLong/WGS84 as projection- Load ISTAT map of provinces or other maps

Third step: Geocoding of unreferenced map 1. Georeferencer tool

2. Load file from PDF

4. Digitize Ground control Points (see next slide)

3. Run geotool in order to digitize points

Fourth step: Geocoding of unreferenced map II

5. Digitize Ground control Points (GCPs) (see next slide)

6. Set GCP from map

Digitizing rules:- use province corners as reference or other distinct features- well distribute ~10 points over the map

Here the coordinates will appear...

Fifth step: Create new vector map to store the WNV points

You can of coursealso add morecolumns in order tosave further attributes.

Sixth step: Enter name for empty vector map (SHAPE format, .shp)

Seventh step: Digitize points

Enter ID, save

Eighth step: Toggle editing to stop/restart editing, save vector map.

Enjoy !! :)

Editing toolbar

Toggle editing on/off

You can of course reload and modify in QGIS.

You may wantto save allas “QGIS project”