# Expected Line Normal

The edit control places an interactive graphic over the Current.InputImage buffer to assist you in specifying the orientation of the line you want to find:

Be aware this is not the search region for locating line segments, which you can configure on the Region tab.

Click on the graphic to enable sizing and rotation handles and use it to specify the expected orientation of the line segments you want to locate. See the following examples for how to use the graphic:

As you use the graphic be aware of the following:

- The graphic does not designate a specific region to search for candidate edge points.

  By default the tool searches a RectangleAffine for candidate edge points in the direction you specify. Use the Region tab to specify a limited region to search for edge points as your vision application requires. Use a Fixture Tool to compensate for how the search region must be reoriented in successive run-time images.

- The graphic does not specify the polarity of the edge points to search for.

  If you specify a polarity that is not available along the search direction, the tool will not find candidate edge points.