Georeferencing in ArcGIS Multiple approaches

Nasir Hameed

Add dataset to be georeferenced

In this example NWFP map is selected, else could be satellite image, Topo sheet, etc. the method will remain same for other maps/images, if points are known.

Right click on the location enables to view the toolbar .

Add on fly projection, coordinate system before starting Georeferencing….. This technique will enable you to insert DMS in selected control points, xy coordinates may also be entered during Georeferencing operation after Converting them from DMS …

Follow the Path:- Predefined---geographic coordinate systems….world….WGS-1984

Back to main window after selecting the on fly coordinate system….later on The resultant rectified map could also be converted to Planner Coordinate Systems like UTM, etc.

Now add known referenced points/coordinates No matter the image is saved from Google or somewhere else, coordinates should be known in order to Georeferencing. If this is not the case then image could still be referenced throgh another rectified/ georeferenced image .

Encircled locations of the map are selected for entering known coordinates in DMS

Left & then right click ..

Dialogue box allows to enter coordinates

Move towards next point….

All encircled points were entered with DMS. ‘Rectify’ allows you to save the rectified image to desire location, format .

Browse for location to save the output file. Tiff format is used for its capability Embed Georef information.

The operation is now completed, remove the image in order to insert rectified image. From where it was saved!!

Insert the image from where it was saved ….the rectified one!

It is now rectified, its showing coordinates wherever you surface the map…. The map is ready to be work on it…

The coordinate system of the resultant rectified image Could be converted to projected coordinate system like UTM, LCC in order to have area, length etc.

Follow the path: Pre Defined… projected coordinate system…..UTM…..WGS1984…….Northern hemisphere…..WGS1984 UTM zone 42 North

Now meters are shown in the lower corner of the map,

Changing coordinate system of image, vector file from other sources!!

Coordinate system can be applied to the map from Arc Catalog and from “tool box” .

This tool works only when coordinate system is not defined during Georeferencing or image is not already assigned coordinate system. You may open this tool before starting Georeferencing as alternate of “on fly projection”.

Launch the application.

Here is our map

Follow the path: Pre Defined… projected coordinate system…..UTM…..WGS1984…….Northern hemisphere…... WGS1984 UTM zone 42 North