O. Image Georeferencing

Owned by Harald Sund (Unlicensed)
Last updated: Nov 12, 2014 by Erlend Kvinnesland

Introduction

This tutorial will guide you through the process of georeferencing a map. To georeference a map or image you need 3 tie points. These points should cover as much of the map as possible. The map in this exercise has a graticule showing latitude and longitude which works great as tie points.

Exercises

 

Exercise

Import an image into your project

  1. Create a Generic folder (i.e. a folder with schema Generic) and rename that folder to My Maps
  2. Right-click the My Maps folder and go to Import > Generic. Browse for a *.jpg or a *.png.
  3. Make sure the schema of the image set to Image Data.
  4. Make sure Specify import area is uncheked
  5. Click Execute
Exercise

Georeference an image

  1. Right click the image you want to geo reference and select Geo Reference
  2. A new window will show the image and the georeference menu will pop up in the lower left corner.
  3. In the first menu specify the original spatial reference of the map. In this case WGS84 and Mercator
  4. Click next
  5. In the Tie point Coordinate Format drop down select 12°34.56' N/S
  6. Type in the values Lat: 32 00 S and Lon: 13 00 W
  7. Zoom into this crossing point on the map
  8. Click on Image pick and click on the crossing graticules in the map.
  9. Select Tie point 2 in the drop down list
  10. Type in the values Lat: 32 00 S and Lon: 1 00 W
  11. Zoom into this crossing point on the map
  12. Click on Image pick and click on the crossing graticules in the map
  13. Select Tie point 3 in the drop down list
  14. Type in the values Lat: 20 00 S and Lon: 1 00 W
  15. Zoom into this crossing point on the map
  16. Click on Image pick and click on the crossing graticules in the map
  17. Once you have georeferenced three tie points the table will provide you with an pixel error. The value should not exceed more than 1 pixel on each point.
  18. Click Finish to complete the georeferencing