Expanded and Adapted from Columbia University Libraries (2010) "Georeferencing an image in ArcGIS," Accessed August 2, 2010 from http://www.columbia.edu/cu/lweb/indiv/dssc/eds/georef.html All information indicated by an asterisk (*) is taken directly from the Columbia University tutorial without change. Other items may have been changed or adapted as necessary.
Georeferencing is the process of aligning spatial data (layers that are shape files: polygons, points, etc.) to an image file such as an historical map, satellite image, or aerial photograph. This document describes the basic steps for georeferencing Georeferencing an image using ArcGIS. |
Preparation
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Add the Georeferencing Toolbar
Click on View → Toolbars → Georeferencing
Add a Georeferenced Basemap to your new Map Project. We recommend adding the ESRI Imagery World 2D Map or ESRI Street Map World 2D from the ESRI servers.
Add the image you want to Georeference to your map project. Raster images - such as .jpg, .tiff, or .png files (all of these are image file types), are actually made up of multiple layers. Click once on the name of the image file and then add it to your map project. If you double click on the image file when using the Add Data feature in ArcMap, you will see something like this:
- Prepare all the spatial layers
- Open all spatial layers you will use to georeference the image.
- Zoom in to the approximate area that is covered by the image to which these layers will be added. This does not have to be exact as it is done just to provide you with an easier workspace.
- Adjust the color and shape of any points so that they will be visible when displayed on the image.
- Polygons will be easier to use if you make them "hollow" (hollow is a choice in the list of fill colors for symbols). Also choose a color and width for the line around the shape that can be seen against the image layer.
- Prepare the Image Layer
- Open the image layer.
- Rescale the image to fit within the window; select from the Georeferencing tool bar:
Georeferencing > Fit to Display
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