Once you have specified the control points, projection and map units of your map and have determined that the error for control points is acceptable, you are ready to digitize your map.
To begin digitizing:
- Make the Map window active and make a layer editable.
- Right-click on the Map window, and click Change View to open the Change View dialog box.
- Set the zoom of the window to be larger than the area of the map you are digitizing. This will keep the cursor in view during digitizing.
- Specify the X and Y coordinates of a point that generally falls in the center of the map to be digitized.
- Click OK.
The Map window shows roughly the same area as your paper map. If you have entered at least three control points in the Digitizer Setup dialog box, digitizer mode should be on, and the digitizer cursor should appear in the Map window.
- Press the D key to turn on digitizing mode. The cursor becomes a cross hair.
- Begin tracing the map.
Implementing or Canceling Your Digitizer Setup
When a Map window is open and a digitizer is properly configured, the option Digitizer Setup command enables on the SPATIAL tab. If this command is not available, MapInfo Pro is not recognizing the digitizer.
To access the Digitizer Setup dialog box:
- On the SPATIAL tab, in the Navigate group, click Digitizer Setup to open the Digitizer Setup dialog box.
Using Autotrace to Trace Digitized Objects
You can trace the nodes of an object using the Polyline or Polygon commands. This makes it easier to digitize objects that share a border because you do not have to re-digitize the shared border. You can also use this feature to trace an existing polygon/polyline network, for example, a street, a county, or some other polyline or boundary.
The words SNAP and AUTOTRACE display in the MapInfo Pro Status bar, located along the bottom of the MapInfo Pro screen.
AutoTrace entry in Status Bar.
Autotrace is available when Snap mode is turned on. Note that you can only use autotrace with existing polylines and polygons. You cannot autotrace rectangles, ellipses, arcs, or other shapes made with the drawing tools.
To autotrace a polyline/polygon while digitizing, do the following:
- Open a Map layer you want to trace a polygon or polyline on and make the layer editable.
- Press the S key to turn on the Snap process and the T key to turn on the Autotrace functionality.
Note: When you press the letter T, you turn on the AutoTrace mode session-wide in any map.
- On the SPATIAL tab, in the Create group, click Insert, and then Polygon or Polyline, and select the first node you want to trace.
- Drag the mouse along the nodes of the line or object you want to trace. MapInfo Pro highlights the path you are autotracing. When you click, MapInfo Pro automatically traces all the segments between the two nodes and adds them to the polyline/polygon you are drawing.
Use the Shift or Ctrl key functionality for this mode. When you AutoTrace a polygon, the path contains the least number of nodes necessary to complete the AutoTrace, which is similar to the Shift key behavior. If you want to trace the longer path, press the Ctrl key to override default AutoTrace direction. AutoTrace works the same way as selecting multiple nodes in Reshape mode.
The Shift key autotraces the shorter path between the two nodes. The Ctrl key autotraces the longer path.
The rules that apply to AutoTrace:
- To enable the AutoTrace mode, you must be using a "poly" tool such as Add Polygon or Add Polyline
- You must press S to enable the Snap feature to use the AutoTrace feature
- You can only autotrace one object at a time
- The second node you Shift/Ctrl-click on must belong to the same object as the first node. If it belongs to a different object, MapInfo Pro draws a straight line between the two nodes. If you click a node that's shared by two objects (for example, a shared border), you can begin autotracing from either polygon.
- When a closed polyline is being autotraced, the trace line never crosses the start and end points of the polyline (so the Ctrl key has no effect).
See Also: