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Procedure for using the RectangleFinder step


The following procedure provides a basic methodology for using the RectangleFinder step:

  1. Define a rectangle model.

  2. Optionally, adjust the RectangleFinder step settings to control the search.

  3. Run the project to the RectangleFinder step to ensure your project works correctly.

Define a rectangle model

To define a rectangle model, perform the following:

  1. Click on the Define rectangle () toolbar button in the Project toolbar.

  2. On the image, click and hold at the corner of the rectangular shape that you are defining; then, drag across to the required height and width. Alternately, set the Height and Width in the Configuration pane.

    Note that a rectangle's width is always its largest side.

  3. Confirm or cancel the defined shape in the Rectangle control panel ( ).

    To redefine the rectangle, click the Redefine shape button in the Configuration pane.

RectangleFinder step settings

The RectangleFinder step settings control the search. Typically, the default settings are sufficient; however, you can specify other values if necessary. To change the default RectangleFinder step settings, perform one or more of the following:

  1. Set the Total number of occurrences, Smoothness, Detail level, Acceptance, and Polarity. Use these, and other Search settings available for all Finder steps, to further control edge extraction and the definition and identification of a match.

  2. Set the Fit score min. Use this to guarantee a certain quality of fit. The fit score is a measure of the correlation of the edges in your model to those in the occurrence. It is equal to [1 - Normalized Fit Error]. A perfect fit gives a fit score of 100.0. The fit error is calculated the same way as in the ModelFinder step. For more information on fit error, see the Fit error subsection of the Determining what is a match section in Chapter 13: ModelFinder step.

  3. Set the Min side coverage. Use this to set the minimum required amount that each side of your rectangular shape must match a potential occurrence's by for it to be considered an actual occurrence.

    Note that at least a portion of each side must be visible.

  4. Set the Deviation tolerance. Use this to find partially deformed or broken rectangular shapes. See the Deviation tolerance section later in this chapter for more information.