Drawing Curves

Feature Description

The application supports various curves: Bézier curve, B-spline curve, Cardinal curve, free curve, and geodesic.

Feature Entry

  • Features Tab->Feature Drawing Group->Line Drop-down List->Curve.

Steps

Drawing Bézier Curve

A Bézier curve is controlled by two start nodes and two end nodes not on the curve, with other control points fitting intermediate positions. At least six control points are required to complete a Bézier curve.

  1. In the Features Tab's Feature Drawing Group, click the Line drop-down button and select Bézier Curve. The Bézier curve cursor appears.
  2. Move the mouse to the map. The parameter input box displays real-time coordinates. Enter coordinates for the first control point in the parameter input box (use Tab to switch between boxes) and press Enter.
  3. Similarly input coordinates for the second to fourth control points to determine the curve's trajectory.
  4. Enter the fifth control point's coordinates. A blue dashed line appears between the third and fourth points as the first fitted segment.
  5. Input the sixth control point's coordinates to draw the second segment.
  6. Repeat previous steps to continue drawing.
  7. Right-click to finish.

B-Spline Curve

A B-spline curve uses two endpoints on the curve and intermediate control points off the curve. Other points are fitted based on these controls. Minimum four control points required.

  1. In Features Tab->Feature Drawing Group, click Line drop-down->B-Spline Curve. Cursor appears.
  2. Input first control point coordinates via parameter input box and press Enter.
  3. Input second control point coordinates.
  4. Input third control point coordinates. Blue dashes appear between second and third points.
  5. Input fourth control point coordinates. Second segment appears between third and fourth points.
  6. Repeat steps to continue drawing.
  7. Right-click to finish.

Cardinal Curve

A Cardinal curve is formed by control points on the curve with other points fitted. Minimum three control points required.

  1. In Features Tab->Feature Drawing Group, click Line drop-down->Cardinal Curve. Cursor appears.
  2. Input first control point coordinates via parameter input box.
  3. Input second control point. Blue dashes appear between first and second points.
  4. Input third control point. Second segment appears between second and third points.
  5. Right-click to finish.

Free Curve

Free curves are drawn by freehand dragging, useful for irregular boundaries or digitizer tracing.

  1. In Features Tab->Feature Drawing Group, click Line drop-down->Free Curve. Cursor appears.
  2. Hold left mouse button and drag to draw freeform path.
  3. Right-click to finish.

Geodesic

A geodesic follows Earth's curvature, representing the shortest path between two points. Used for global navigation routes. Requires Global Pan activation.

Example steps for drawing airline routes:

  1. Open "World.smwu" sample workspace. Add "world map_Day" and editable route dataset to map.
  2. In Features Tab->Feature Drawing Group, click Line drop-down->Geodesic.
  3. Left-click start and end points. Right-click to finish. Apply layer styling for results:
Figure: Airline Route Map