Image Georeferencing - Map
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
- Create a Generic folder (i.e. a folder with schema Generic) and rename that folder to My Maps
- Right-click the My Maps folder and go to Import > Generic. Browse for a *.jpg or a *.png.
- Make sure the schema of the image set to Image Data.
- Make sure Specify import area is uncheked
- Click Execute
Exercise
Georeference an image
- Right click the image you want to geo reference and select Geo Reference
- A new window will show the image and the georeference menu will pop up in the lower left corner.
- In the first menu specify the original spatial reference of the map. In this case WGS84 and Mercator
- Click next
- In the Tie point Coordinate Format drop down select 12°34.56' N/S
- Type in the values Lat: 32 00 S and Lon: 13 00 W
- Zoom into this crossing point on the map
- Click on Image pick and click on the crossing graticules in the map.
- Select Tie point 2 in the drop down list
- Type in the values Lat: 32 00 S and Lon: 1 00 W
- Zoom into this crossing point on the map
- Click on Image pick and click on the crossing graticules in the map
- Select Tie point 3 in the drop down list
- Type in the values Lat: 20 00 S and Lon: 1 00 W
- Zoom into this crossing point on the map
- Click on Image pick and click on the crossing graticules in the map
- 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.
- Click Finish to complete the georeferencing