Polygon Nudge Tool

The Polygon Nudge tool allows you to adjust the size and shape of irregular ROIs and measurements.

The nudging technique for reshaping polygons and polylines allows you to push control points around, rather than clicking and dragging them. This technique makes it easy to contour curves in curvy polyforms by 'nudging' the control points into place.

To use nudging mode:

1. Enable nudging mode by right-clicking the mouse in the image window, and clicking on the Polygon Nudge tool in the popup context menu.

   Initially the nudge tool will be a dashed circle and has no effect on the selected object.

2. Use the mouse wheel to adjust the size of the nudge tool

   The size of the nudge tool determines how many controls points it can nudge at one time.

3. Press the mouse button and move the nudge tool into the control points you want to nudge.

   Notice that, when you press the mouse button, the circle becomes solid and shows an arrow tracking the direction of mouse movement, and the nudge follows the direction of the mouse movement. The nudge tool is designed to operate only at slow speeds. So by moving quickly, you can skip the tool from one side of a polyline to the other or from the exterior to interior of a polygon without needing to let up the mouse button and without disturbing the boundary as it is quickly crossed. This may take some practice to master, but it is often necessary to nudge from both sides of a poly line section to get a boundary placed correctly, so using this technique can speed things up.

   Holding down the <Ctrl> key while editing a polygon or polyline temporarily leaves nudge editing mode to allow you to insert (<Ctrl> double-click) or move (<Ctrl> drag) a single control point.

4. To turn nudge mode off, press the space bar.