I have only a jpg map but don't have any digital data for georeferencing that jpg. So is there any way for georeferencing my map (like googlemaps)?

  • All links provided to guide to georeference maps are not available or access denied. what can I do now? – Isaac Bazugba May 3 at 7:28

Yes there is, but before that, what software do you have available? To georeference a non georeferenced jpeg you will need to know/have one of two sources of information.

1) Access to vector or raster data that covers the same geographical area in the jpeg 2) Knowledge of the geographical extents of the jpeg (ie: Lat/Long cooridinates or UTM coordinates)

With this information you can georeference the jpeg in a GIS software package such as QGIS, ArcGIS, ERDAS Image, PCI Geomatica etc.

Here are three links to how you would perform this task.

http://courses.umass.edu/nrc297s/PDFs/Lab_Georeferencing_with_QGIS.pdf http://ocw.tufts.edu/data/54/626689.pdf http://adielflitzow9.files.wordpress.com/2008/02/georectify.pdf

  • +1 you have to know the projection of the jpeg, and match it with whatever you're georeferencing from. – Roy Jun 29 '12 at 17:58
  • 2
    @Roy Yes it helps to know the projection, but it's certainly not necessary, as anyone who has ever georeferenced an undocumented, historical, or site-specific map can attest. – whuber Jun 29 '12 at 18:14
  • This is very true. I do this try of work daily and you can decide what projection you want the output georeferenced image in. The most important thing is to know where in the world it is. The precision of the information you have will allow you to potentially have a more accurate georeferenced image. – Ryan Garnett Jun 29 '12 at 18:17

To georeference an image, you should know the lat/long values of at least 3 locations on the image. The more the better. These are called GCPs (Ground Control Points). Once you have the GCPs, you can transform the image to fit in a real world coordinate system (like lat/long). Many times you can get coordinates from the markings on the scanned map image itself.

This help article has useful information for ArcGIS 9.3 http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Georeferencing_a_raster_dataset

If you want to try this in QGIS, I have a step-by-step writeup http://qgis.spatialthoughts.com/2012/02/tutorial-georeferencing-topo-sheets.html

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