Tuesday, March 29, 2005

Counting Features with GTViewer

GTViewer provides the ability count features or elements in a polygon. There are several ways to perform counting:

Method 1:

  • Create a polygon with session graphics (redlines). The Rectangle, Shape, or Circle element can be used.
  • Select the session graphic you wish to use for the counting. Use the Draw/Select command (or press the northwest arrow icon on the session graphics toolbar), then click on the session graphic element you wish to use. The session graphic will highlight and vertex handles will be displayed when it is selected.
  • Select Tools/Count to get to the Count Options dialog. This option will only be enabled if there is a single valid polygon element is selected.

Method 2:

  • Use the Attribute Info Mode and review a feature or element.
  • The Attribute Info Dialog box will have a Count button at the lower right if GTViewer can make a closed polygon out of the selected element. Press the Count button to get the Feature Count Options Dialog.

Method 3:

  • Perform a Thematic Query to highlight features.
  • You can select and/or create a session graphic polygon to count in (as described in Method 1) or you can choose to count all highlighted elements (an no polygon needs to be selected).
  • Select Tools/Count to get to the Count Options dialog.

The Count Options dialog is shown below. Depending which method you used from the above list, different options will be available to you on the Count Options dialog. Methods 1 and 2 will always provde the By General Rules and By Feature option. However, if Method 3 is used, you will have the By Highlighted Feature (All) and possibly the By Highlighted Feature (in Shape) option if a polygon was also selected.

The By General Rules method allows you do specify basic conditions that must be met before an element will be counted:

  • Only Features with Attributes – with this option selected, all features in the polygon must have a linkage to database information before they will be counted.
  • Ignore Text Elements – with this option selected, text elements are not counted. For Framme data, this option does not ignore symbols even though they are technically text elements (fonts are designated as either text or symbol and this characteristic will allow symbols to be counted even when text is ignored). This option does not affect the counting of symbol elements.
  • Only Visible Features – with this option selected, only elements that are currently visible will be counted. Visible means that their Category is displayed and the features are not filtered. The elements do not have to be currently in the view to be counted with this option selected, they just have to be in the selected polygon.

The By Feature method allows you to specifically define which feature or features you want to count. You can select more than 1 feature by holding down the Ctrl button when selecting.

The By Highlighted Feature (in Shape) method allows you to count highlighted elements that may result from a Highlight Query or an External Application. This option is only available if a valid polygon element has been selected and Highlighted elements are present (as the result of a Thematic query or a custom application).

The By Highlighted Feature (All) method allows you to count all highlighted elements that may result from a Thematic Query or a Custom Application. No selected shape is required to use this method and this option will be available anytime highlighted elements are present.

Once you have selected the method to use for counting, press the OK button. The counted elements will highlight on the screen as they are counted. When counting is complete, you will be presented with a Count summary dialog. This dialog will show the total count for each feature counted. If the features were linear elements, the total length of the linear elements that fell inside the polygon will also be presented.

The view will highlights all of the features that are in the selected Polygon. Linear elements that pass through the polygon or are only partially contained by the polygon are highlighted appropriately:

You can select an item in the Count summary dialog box and press the Detail button (or just double-click on the item). A Count Details dialog will be displayed showing the primary record for each feature in the selected group. The primary record is the record for a feature with the lowest display priority value.

In the Detail dialog you can select an item and press the Locate button (or just double-click on the item) to locate the specific feature in the current view. The Detail dialog also have several other options:

  • The Info button will display the standard Attribute Info dialog for the selected element.
  • A Copy button is available on both the Summary dialog and the Detail dialog. By pressing this button, the contents of the dialog will be copied to the Windows clipboard. The information can then be pasted into another application like Excel.
  • The Save button will save the information as a Comma Separated Value (.csv) file.

The Count Functionality in GTViewer provides an easy way to gather information about your data. Count results can be easily saved as reports and the graphical results can also be exported to other applications. This is just one feature that lets you get the most out of your data.

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