When a spatial image is opened, Geographic Imager will automatically detect whether it is georeferenced or not. When an image is recognized as a spatial image, the Geographic Imager panel displays the name of the reference file and additional information: the northwest (top left) and southeast (bottom right) corner coordinates, image size, pixel size, and rotation angle. Units are not indicated if no coordinate system is specified. For a spatial image to be recognized, an external reference file (e.g. World file) needs to be in the same folder as the image, except for files that have internal referencing (e.g. GeoTIFF).
An opened image (GeoTIFF) has an internal reference file and is listed as "boston-east.tif"
When a reference file is not found, it may be necessary to manually specify one. Once a reference file is specified, any changes to an image’s referencing will be reflected in the reference file when the image is saved.
How to specify a reference file
1.Click the Reference File Specify link in the Geographic Imager panel.
2.Alternatively, in the Geographic Imager panel options menu, choose Specify Reference File. In the Choose a Reference File dialog box, browse and select a reference file of one of the supported external reference formats listed in the File Type drop-down list.
When multiple reference files match the image name are located in the same folder, you will be prompted to choose the appropriate reference file. Any changes in document georeferencing will be saved to the chosen reference file.
If no reference file is available but a collection of point coordinate locations are known (such as the Top Left corner and Bottom Right corner coordinates), a custom reference file can be created. See more about Georeferencing.