The EdgeLocator tool is used to identify edges along the path projection of the tool. EdgeLocator tools are either linear or in the form of an arc. Using the edge locator properties, you can find edges possessing the characteristics of interest to you. The tool reports the polarity, strength, and position of an edge.

You can find edge pairs possessing the characteristics that interest you by setting the caliper properties, including setting constraints, minimum strength and polarity requirements, location, and dimensions.

In the following dialog box, the Caliper Tool’s Edge Evaluation function is being used to fine tune the edge selection criteria.

• Generate a projection of the analysis path. In monochrome processing, it creates a one-dimensional array of the average light intensity on each line that crosses the path. In color processing, the tool determines the color definition based on color analysis in RGB or HSI 3-space.
• Generate an edge strength array. The graph of the array can be displayed in the image window of the tool’s property page. Peaks in the graph indicate strong edges. Differential filters can be applied to the projection array to smooth the edge strength graph.
• Determine locations of edges. Peaks in the edge strength graph can be identified using the edge strength values that are higher than the surrounding elements in the edge strength array.
• Apply discriminators to the list of edges. Constraints are the basis of the detection method and can be specified for individuals edges based on position, strength, or both. They can be used to indicate the optimum position, set minimum required edge strength values, and identify edges by positive and/or negative polarity.
• Score the qualifying edge. Scores are determined according to each active constraint and are based on the EEF defined by the designer or user.
• Extract edge location data. The edge tools return data such as edge position, strength, score, polarity, number of edges, and mid-point and size of caliper edge pairs.