What follows are some common digitizing problems that may occur in MapInfo Pro and what you can do to correct them.
Selecting a Drawing Command and Making the Map Window Active
To begin digitizing:
- A drawing command must be selected
- The Map window must be made active
- The D key must be pressed.
The D key toggles digitizing mode on and off. When in digitizing mode, the cursor will appear as a circle with a crosshair in it. If you draw on the screen without the digitizer cursor, then coordinates entered into the package are relative to where the cursor is on screen. The cursor, even though driven by the digitizer tablet, is just a screen pointer until digitizing mode is entered. Once in digitizing mode, the control point transformation is put into effect, and coordinate information is taken from the tablet, not the screen.
- Make sure the coordinate system, projection, map orientation and map units are known and properly set in MapInfo Pro.
Improper initial setup may lead to inaccurate results that can only be corrected by starting over. Remember that the Projection button on the Digitizer Setup dialog box (on the SPATIAL tab, in the Edit group, click Digitizer Setup) refers to the paper map to be digitized, whereas the Projection button on the Map Options dialog box (in the Layers window, right-click the map name and select Options) refers to the map you are digitizing into. It is possible to digitize a map in a certain projection to a different projection. The Digitizer Setup projection must match the paper map projection, and the Map Options projection matches the projection you want to digitize into.
Make sure there are at least 4 known coordinate locations on the map/drawing that can be used to set control points, the more control points that are added, the more accurate the transformation from tablet to Map window will be.
The accuracy of these control points will directly affect the accuracy of the digitized map. It is best to select control points that are not too close and do not share any Latitude or Longitude coordinates. In general, more control points yield more accurate results.
High error when configuring control points (>.090) (Digitizer)
- Control points were not properly entered.
- The map has moved while setting control points.
- The control points are inaccurate.
- The map being digitized is inaccurate.
Map is coming out backwards (Digitizer)
- The map may be oriented improperly on the tablet. Check orientation of control points; positive and negative may be reversed. It is useful to have the cursor location displayed while in digitizing mode.
To do this, on the MapInfo Pro Status bar, click on the the scale value to display a list of options (this is located on the lower-left corner of the MapInfo Pro screen). Select Cursor Location. When the cursor is placed over a control point in digitizing mode, the cursor location should match the coordinates of the control point.
When switching into digitize mode, the cursor disappears
- Change active zoom and center of window to represent the zoom and center of the map/drawing being digitized. Often using a control point as the center of the window, toggling into digitize mode and placing the cursor directly over the control point will make the cursor appear.
Digitizer cursor jumps off screen when digitizing
- Increase the active zoom to better reflect the zoom being digitized. You must be in Digitizer mode (press D) to digitize but the digitizer cursor does not have to be visible in the Map window. On the MAP tab, pointing to View Entire Layer may be helpful when working with a pre-existing map. It is also possible that the tablet is damaged and has empty spots.
Can not access all parts of screen when using digitizer as mouse
- Digitizer should be configured as Absolute=1, so that the tablet represents the whole screen. If Absolute is on, it is possible that the tablet is configured incorrectly, or the wrong tablet has been selected in setup. It is also possible that there are damaged spots on the tablet.
Distances do not measure properly (Digitizer)
- The only way to measure a distance of a segment on a map being digitized is to digitize the segment into a Map window and then use the Ruler command to measure the segment. If a digitized segment measures incorrectly, then there is a setup problem, which could range from map properties (units, projection, etc.) to control points, to inaccurate digitizing.
Digitizer setup is unavailable even though the digitizer is connected
- The tablet driver is not supported by the operating system.
- The tablet is not turned on or is incorrectly connected to the computer.
- The tablet is improperly configured, see the tablet driver documentation.
- The wrong tablet/driver combination is being used.
- There is a problem with the tablet, the comm port, or the connecting cables.
If the tablet works with other applications or is being used as a mouse pointer in Windows, and none of the above problems apply, there may be a problem with our support of the tablet. If possible, configure the tablet to emulate different tablets supported by MapInfo Pro. Make sure the system.ini file is updated to reflect the changes, and restart Windows each time a change is made to the system.ini.
Digitizer Mode - D Key
You must be in digitizer mode when you begin to trace your paper map. This is so MapInfo Pro can recognize the coordinates and place the map in the correct geographic context. If you trace the map in mouse mode, you are only drawing objects that do not have any tie to your paper map.
You are in digitizer mode when you click the D key or when you have entered at least three control points in the Digitizer Setup dialog box. You should see the digitizer cursor in the Map window. It is a large cross hair that covers the entire width and height of the Map window. A Map window must be active for the digitizer cursor to display. The Status Bar will also say DIG when you are digitizer mode.
Digitized Map Does Not Display in Expected Location
If your map does not display in its proper geographic location, it is likely that you did not specify the appropriate negative degree coordinates for your control points. If you zoom out to view the entire world, you will see your points in a different area.
At the Digitizer Setup dialog box, be sure to specify negative coordinates if your map includes west longitude and/or south latitudes. For instance, for maps in the United States, you should specify a negative X coordinate. For Africa, the Y coordinate is negative. For South America, both coordinates are negative. (For Europe, both coordinates are positive).
If you still do not see your map in the expected location, it could be due to bad control points, incorrect projection, or map units, etc.
High Error for Control Points
A high control point error means that MapInfo Pro thinks there is a discrepancy between the point you chose on the tablet and where the point should be, based on the coordinates you specified. This can lead to inaccurate maps.
To reduce the error, edit the control point to be more precise with your click. Check to make sure the coordinates you entered are correct. You can also increase the number of control points.
Distances Do Not Measure Properly
If you measured a segment on the tablet using the puck and Ruler command, you will come up with inaccurate results. The only way you can measure a segment is to first digitize it, then use the Ruler command to measure it on screen.
If you still have bad results, it could be due to a setup problem (check projection and map units), control point problem (high error estimate, recheck coordinates), or inaccurate digitizing.
When Switching to Digitizer Mode, the Digitizer Cursor Does Not Appear
If you do not see the cursor when you switch into digitizer mode, check to make sure the coordinates are correct. You may need to specify negative coordinates (see Digitized Map does not Display in Expected Location, above).
Other things to do:
Set the center of the map to be one of your control points. In the Change View dialog box you can specify the coordinates of a point that falls in the general center of your paper map.
Put the cursor exactly on one of the control points.
Digitizer Cursor Jumps Off Screen When Digitizing
This happens when your Map window is set at a much different zoom than the map you are digitizing. Increase the active zoom to better reflect the area being digitized. For instance, if the map you want to digitize is 300 miles across, set the Map window zoom to about 300. On the MAP tab, click the launcher button located beside the Navigation group name to open the Change View dialog box. In the Zoom (Window Width) field enter a value of 300.
You do not have to see the digitizer cross hair to digitize, but it is helpful. View Entire Layer (right-click on the map to locate this option) may also help, if working with a pre-existing map. It is also possible that the digitizing tablet is damaged and has empty spots.
Digitizer is Connected but Digitizer Setup is Unavailable
Check the following:
- MapInfo Pro supports the digitizing tablet you are using.
- Make sure the tablet is turned on and is correctly connected to the computer.
- The digitizer driver is properly installed.
- The tablet is properly configured.
- The right tablet/driver combination is being used.
- There is no problem with the tablet, the connection, or the connecting cables.
If the tablet works with other applications or is being used as a mouse pointer in windows, and everything listed above checks out fine, there may be a problem with our support of the tablet. If possible, configure the tablet to emulate different tablets supported by MapInfo Pro. Make sure the system.ini file is updated to reflect the changes, and restart Windows each time a change is made to the system.ini.
If the tablet works with other applications or is being used as a mouse pointer in windows, and everything listed above checks out fine, there may be a problem with our support of the tablet. If possible, configure the tablet to emulate different tablets supported by MapInfo Pro.
Digitizing Two Maps
You must set control points for each map individually, even if the maps are adjacent.