Digitize Contour Lines

Digitize a series of multi-segment lines representing topographic contours at constant elevations by streaming points (adding points as you hold down the digitizer button and move the puck, and releasing the button at the end point). The contour polylines can be incrementally elevated automatically, based on a specified starting elevation, increment direction, and contour interval.

The streaming method is optimized for digitizer input; you can change the increment direction or elevation for each contour polyline from the digitizer puck without returning to the on-screen command pane. After you set up your digitizer, this enables you to quickly and simply digitize multiple polylines using the Workflow for digitizing multiple contour lines at the end of this topic.

To digitize contour lines:

Select Digitize Contour in Takeoff > Digitize.
The Digitize Contour command pane displays.
In the Name box, type an identifier for the line as you want it to appear in the Selection Explorer and graphic views. You can also use the name to select the line in the Advanced Select command.
Select the layer on which you want the line to reside in the Layer list, or select <<New Layer>> to create a new layer for the line.
Specify the elevation to be applied to the first polyline of the series in the Elevation box.
To have the first and last point in the polyline automatically connected by a segment when you finish, check the Close by connecting ends if ends are close box.
Note: If you are using an actual digitizer, the tolerance for connecting ends is 2 mm or 1/10th of an inch on the digitizer pad, depending on your project units. If you want to create an open contour, simply keep the end point further from the start point than this distance. After creating a polyline, you can always change the Closed property in the Properties pane. If you are simply 'digitizing' on screen, the tolerance is 1/2 of the Circle filter type's Radius.
To digitize each line at the same elevation, uncheck the Increment after each contour box. Otherwise, the elevation will increment or decrement for each polyline that you digitize.
If you are using automatic increments, specify the vertical distance between each line in the Contour interval box, and specify whether to increment each subsequent elevation by the interval either up or down each time you digitize a new line.
Specify the elevation of the first line you will digitize in the Current elevation box.
Select a Filter type below the Next points box:
- Circle - In the Radius box, specify the minimum radial distance from the last point that the next point can be added.
- Tube - In the Length and Width boxes, specify the minimum rectangular distance from the last point that the next point can be added. Polylines are drawn in 2D, so this is not a 3D filter.
  Tip: Start with a filter radius/length of 3 feet/1 meter. Then adjust the tolerance up or down depending on your needs.
  Note: If you start a new polyline, the same filter settings are used until you change them.
Click in the Next points box.
Pick the first point of the contour line on your paper plans with the digitizer puck, hold down the button, and move along the path. At the end of the polyline, release the button. Points are created at a regular interval, based on the tolerance set in Filter Settings.
Note: If you digitize a point near the edge of the Plan View (1/20th of the view's height or width), the view will automatically pan (auto-pan) your last point to the middle when you release the mouse button. You can control the auto-pan settings in Options > Digitzer.
Press [Enter] or click New to start a new polyline. The elevation of the new polyline is automatically incremented (if you opted to) and the focus returns to the Next Points box.
When auto-increment is enabled, to change the increment direction or starting elevation from the puck while in the Next points box:
- Press – (minus) to toggle the increment direction.
- Press • (dot/decimal) to increment the current elevation.
  For example, if you digitize and automatically increment contours with elevations of 448, 450, and 452, and then need to digitize a contour with an elevation of 450 again, press -, then •, and start streaming the contour.
  Note: While in the Next points box, you can press [Backspace] to undo the last segment that was created.
  Note: When auto-increment is disabled, you can type the elevation for the polyline on the puck's keypad while in the Next points box.
Click Close when you are done.

Workflow for digitizing multiple contour lines in series

Set up the common name and layer properties for the contours.
Specify the first contour polyline's elevation.
Choose the filter type and tolerances to use.
Stream points using the digitizer puck and press [Enter].
When needed, change the increment direction and elevation while still in the Next points box by pressing - or • on the puck. Then digitize points for that polyline, and press [Enter].
Repeat step 5 to digitize additional polylines.