Spatial Data Handling

Georeferencing Images and CAD Data

As we often say, the beauty of GIS is that new information emerges when we bring together independent observations. This tutorial will demonstrate how to georeference scanned maps, aerial photos and computer aided drafting files so that their value can be multiplied by association with other georeferenced data layers. The GSD GIS Manual Page, Sources of Geographic Images provides links to resources where you can find an infinite amount of image-based GIS data. Some of it is georeferenced already. Some scanned maps have coordinate system information in the margins that can be used to georeference the image without reference to any other data. This can be useful for beginning a spatial framework for areas, like China or countries of the former British Commonwealth where it is illegal or prohibitively expensive to obtail and exchange good controlled GIS layers. Where good GIS layers can be found, the process of georeferencing an image is surprisingly easy.

Tutorial Dataset

Create a folder for yourself, if necessary in c:\temp Expand the zip archive into to c:\temp