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Registering a Raster file in MapInfo Pro

Products Affected: MapInfo Pro™
Registering the Coordinates of a Raster Image

Before vector data can be properly displayed on top of a raster image, the raster image must first be registered so that MapInfo Pro can position it properly in a Map window,(i.e. "georeference" the table).

In the Image Registration dialog box, the process involves identifying control point coordinates and specifying the appropriate projection for the raster image.

Control points are the coordinates identified on the raster image that MapInfo Pro can use later to match up to other layers.
It is important to provide accurate control point information when registering a raster image, so MapInfo Pro can display raster images without distorting or rotating them.
Later, when vector data is added to the mapper, MapInfo Pro distorts and rotates the vector data so both layers can line up properly.
Identifying significant control points makes this match up process easier.
It is suggested that highway/street intersections and prominent landmarks be used as as control points, as they rarely move.

Specifying the correct projection of the raster image is also important for accurate display. Images that do not have known projections, such as unrectified aerial photographs, are less suitable for use with vector data.

There are two ways to register a raster image in MapInfo Pro and each involves specifying the map coordinates of control points on a reference map and matching them with equivalent points on the raster image.
To determine map coordinates:
  • Identify a point's coordinates from the paper map.
  • Determine a raster images control point coordinates on screen and automatically transfer the information to the Image Registration dialog box.
Note: If the image was scanned from a paper map, the map most likely contains a graticule (i.e. latitude and longitude grid). 
Those coordinates can be used for prominent features and entered in the Image Registration dialog box.

To register the coordinates of a raster image and create a .TAB file from the raster image:
  1. On the HOME tab (64-bit versions), in the File group, use the "Open" drop-down , and then click on "Table" to open the Open Table dialog box.
  2. In the "Files of type" drop-down list, select the Raster Image file format.
  3. Browse to the raster image file, and click "Open" and the "Display/Register" dialog box opens.
  4. Click "Register" to display the "Image Registration" dialog box. This dialog consists of a Control Points list box and a preview of the raster image.

User-added image
 
5. Choose the Projection button to specify the raster image's projection. It is easier to match up the maps if the same projection for the raster image is selected as the vector images (layers) the raster will overlay. Choosing the same projection minimizes image distortion when overlaying the vector map layers. The projection cannot be changed from the Map window.

Note: If the projection is not set, MapInfo Pro defaults to Longitude/Latitude or to the default table projection set by using the map window preferences that are set.
6. The units for the control point entries can be set by clicking the Units button.
7. To select the actual coordinates to register in the raster image, either:
a) Click the "Add" button to add a new entry into the Control Points list box and then double-click the new entry.
or
b) Click on the image or map to add a control point to open the "Add Control Point" dialog box.


User-added image
8. Specify the coordinates from the paper map in the dialog box. The location of each point is marked on the preview image with a "+" symbol. 
The Label can be edited to something more meaningful, such as US85/LA132, to describe an intersection in the raster map. It might be helpful to also select a prominent building or other very specific address that is easily identifiable in both maps.

Note: If a MapInfo Pro map layer of the same area and projection exists, it can be opened in a separate Mapper window. Then on the "TABLE" tab, in the "Maintenance" group, click Raster, and "Select Control Point".
  1. Repeat this process (step 6 and step 7) until at least three or four points on the raster image have been registered. Try to vary the position of these control points to better define the map. If too many points are in a straight line (i.e. more than 2) , an error displays.                                                                                                                
  2. If working with an image for which the projection is not known (such as an aerial photograph), enter at least three control points to improve accuracy.

When the control point entries are completed, click OK. The raster image displays as a .TAB file.

Use the "+" and "-" buttons to zoom in and out of the raster image. Zooming in on the image may help in obtaining greater accuracy in control point location.
If it is difficult to find a control point in the "Image Registration" image, click the control point entry in the "Image Registration" list and click the "Find" button to display the point in the image.

When the "Image Registration" dialog box  is completed, MapInfo Pro saves the registration information in a table (.tab) file.
In later MapInfo Pro sessions, the table can be re-opened without repeating the registration process, and without having to choose Raster Images as the file type in the "Open" dialog box.

Choosing Control Points from an Existing Map

To transfer the coordinates automatically from a vector map to a raster image, a vector map of the same image I needed.
Then display the vector map side by side with the "Image Registration" dialog box, which shows a preview of the raster image.
Click a prominent feature in the vector map to determine its coordinates and transfer this control point to the "Image Registration" dialog box.

To register the vector map control points to the raster image:
  1. On the HOME tab, in the File group, on the Open list, click Table to open the Open dialog box. Select the Raster Image file format.
  2. Choose the raster image file and choose Open. The Display/Register dialog box displays.
  3. Select Register. The Image Registration dialog box displays. Choose the Projection button to specify the image's projection, if necessary.
  4. To add control points, click the Add button to add a control point entry to the Control Points list.
  5. Click the Pick from Map button. The Edit Control Point dialog box displays with the new control points in the Map X and Map Y fields. Click OK to save these entries.
  6. Double click this entry in the Control Point list and click the matching control point location in the image pane. MapInfo Pro updates Image X and Image Y coordinates in the Edit Control Point dialog box with the selected coordinates.
  7. Click OK to save these entries.
Note: Remember to type a meaningful description of this location in the Label field.
 
8. Repeat this process until three or four non-linear points have been identified in the preview pane of the Image Registration dialog box.
9. After all of the control points have been defined, click OK in the Image Registration dialog box. The raster image displays in the Map window under the vector layer.

Note: These entries can be modified on the TABLE tab, in the Maintenance group, by clicking "Raster" and "Modify Image Registration".
UPDATED:  June 21, 2019