Earth Resources Mapping (ERMapper) raster data in .ers files. ERS files, like ESRI BIL, can contain multiple channels, which can represent photography imagery or other raster data, such as terrain elevations. ERS format will sometimes provide coordinate system information, so images may import with coordinate system automatically assigned. However, the coordinate system information may be slightly off, as in the example below, or no coordinate system information may be provided.
To import from ERS format:
Choose File-Import from the main menu.
In the Import dialog browse to the folder containing data of interest.
Double-click the file ending in .ers for the data of interest.
A table and one or more images will be created.
Our example import creates one table and three images. That usually indicates the ERS file stores raster data with three channels, such as an RDB image, and that we may have to combine the various channels into a single image as shown in the Example: Import BIL and Combine 3 Bands topic.
We can double-click on images that are created to view them. For a more interesting display, we first create a new data source using a Bing street maps image server as shown in the Example: An Imageserver Tutorial topic. We then create a map and drag and drop the Bing layer into the map, and then we drag and drop the image into the map.
The airphoto 1 image seems to appear in the right projection, in a San Diego neighborhood. On closer inspection, it seems OK in East/West position but appears to be shifted to the North by about 500 meters. We can use the Tracker tool to measure the distance from the centerline of the highway shown in the image to the centerline of the highway shown by Bing, and it appears to be exactly 500 meters. That seems too close to an exact number to be a coincidence, so we can try to provide a better initial coordinate system by repairing the coordinate system.
In the Components pane we see that the airphoto 1 image uses a Transverse Mercator projection. We click the coordinate picker button, choose Repair Initial Coordinate System, and then choose Edit Coordinate System to launch the Coordinate System dialog.
We change the False northing value from 0 to 500 meters and press OK.
Surfacing back up to the Component pane we see we have set a Custom Coordinate System for the airphoto 1 image.
In the map window, the image now appears to be perfectly georegistered. We can add a False northing of 500 meters to the other two images created by the import as well.
Repair Initial Coordinate System
BIL, ESRI Band Interleaved by Line
Example: Spectacular Images and Data from Web Servers
Example: An Imageserver Tutorial
Example: Import BIL and Combine 3 Bands