Boundary File Filters - Lat/Lon Rectangle

Q: I don’t want to plot the entire state boundary file with my relatively small coverage area. How can I plot just a part of the file within certain latitude and longitude limits?

A: The TAP Map Window plotting allows you to plot boundary files you select. If you want to plot only part of a file, you can use one of the boundary filter programs to create a new file containing only the objects you want to plot. (With the Map Window, you could plot the entire file, then use the zoom features to show and print only the area of interest. However, using the boundary filter programs will allow you to save time and disk space for the drawing file.)

Several filter options are available, depending on what you are trying to do. You can filter by:

This document describes using the filter by latitude-longitude rectangle program.

Filter by Lat/Lon

  1. Suppose you want all of the county boundaries within certain latitude and longitude limits (such as a rectangle defining your target coverage area). From the TAP Boundary menu, select "Filter by Lat/Lon".

  2. This will display the Rectangle Filter form. Click the "Select" button to choose the input files you want to read and filter:

  3. You can select the boundary file(s) to use. To select multiple files, hold down the Ctrl key and click on each file you want. (In this example, the Arizona file is selected to illustrate the multi-select option.)

  4. Click "OK" to use the files you have selected.

  5. The selected files will be displayed in the "Input Files" list:

  6. For the lat/lon filter, we need the limits as latitude and longitude values. Enter the coordinate values for the north and south, and the east and west limits. (The order of the latitude values and the longitude values does not matter.)

  7. The check boxes marked "Containing" and "Intersecting" allow you additional control over the results of the program that are written to the output file.
  8. If you want objects (county lines, roads, etc.) in the input boundary files that are completely (i.e., all points) inside the specified coordinate limits, check the "Containing" box. If you want to include objects that are partly within the limits (i.e., some points are within the limits, and some points are beyond the limits), check the "Intersecting" box.

  9. For example, if you want only those counties that are completely within coordinate limits, you could check the "Containing" box and uncheck the "Intersecting" box.
  10. Enter the name of an output .BNA file where you want to write the results. (You can also use the "Browse" button to find an existing path and/or file.)

  11. Click the "Start" button to begin the filter process:

  12. If the path you entered does not exist you will be prompted with a question about creating the path:

  13. If the file already exists, you have the option of overwriting the file or appending to the existing file:

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  14. When the filter process is completed the number of objects written to the new file will be displayed near the "Start" button. Click the "Close" button to continue.

  15. To view the file you just created, select "New Map" from the TAP File menu:

  16. On the Coverage Plot form, click the "Boundaries" button:

  17. Find the path and file you just created, then click the "OK" button:

  18. The file will be displayed in the boundary file list. Click the "Continue" button:

  19. On the Coverage Plot form click the "Plot" button:

  20. The filtered boundary file will be displayed, showing only those counties within the coordinate limits.

 

Copyright 1999 by SoftWright LLC