Using Streets & Trips to Generate Polygons For an Arc/Poly Filter in GSAK



The arc filter as described in GSAK is "The polygon filter allows you to specify an irregular shape. GSAK creates a filter that includes all caches within the shape. The start point and end point must be the same in order to define a closed shape." Optionally you can do the inverse and exclude caches within the polygon.

Rather than entering the coordinates manually, MicroSoft Streets and Trips (amoung other programs) can be used to generate a file which can then be used by the arc/poly filter in GSAK. Of course GBSBabel is working hard behind the scenes and arc filter functions could be performed by GPSBabel alone if you're so inclined.

This tutorial is divided into three sections:

  1. Setting Up A Polygon In Streets and Trips
  2. Converting the Streets and Trips file to a GPX file
  3. Using the Arc/Poly Filter In GSAK
If you have any questions or comments please e-mail me.


Setting Up A Polygon In Streets and Trips



On the Drawing toolbar, click "Freeform"




Draw a line around the area of interest. Note that you do not have to end the line exactly at the start point but can right click on the line and select "Close Curve". GSAK also has a feature to automatically "close the loop" for you but I find this gave me inconsistent results.




Save this file somewhere you can find it easily again..



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Converting the Streets and Trips file to a GPX file.


An open source freeware program ST2GPX is used to convert the Streets and Trips .est file to a .gpx file that can be used by GSAK. Download it from here and unzip it into a suitable directory. To simplify usage we're going to create a batch file similar to what's described here



Using Notepad create a BATCH file called ST2GPX.BAT in the same directory as ST2GPX.EXE. In that batch file, put a single line

st2gpx %1 -G %~n1.gpx

You can copy and paste the line above if you want. Be sure to save the file with the .BAT extension.





For this to work properly next we'll create a shortcut to the batch file as shown above.




Now drag and drop the .est file onto the shortcut icon to convert the file.




Congratulations you now have a GPX file with the polygon points you created in Streets and Trips. Now lets use this file in the arc/poly filter in GSAK.

Note: Do not double click on this GPX file as GSAK will want to open a database for it.

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Using the Arc Filter In GSAK




Open GSAK and click the filter icon on the tool bar.




On the Set Filter Arc/Poly tab (1) select Polygon for filter type (2) select load from file (3) highlite the gpx file we just created and (4) select Open.






(1) GSAK imports the coordinates of the route points from the GPX file. (2) Select Exclude if you want to filter for caches outside the polygon. Save this filter if you want to use it again in the future. (3) Select Go to run the filter.




GSAK filters the database to show the caches within the polygon. In my example 172 out of a total 4595 caches in the Alberta database are shown in the filter.



To check the results export the filter results from GSAK (link) and import them into Streets&Trips(link). The caches in this image are shown as red triangles.



The results with the "Exclude" option selected on the same arc/poly filter. The caches in this image are shown as blue triangles.

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Many thanks go to the developers of these great programs - Robert Lipe -Chief Babel-Head (and all the rest of the Babel-Heads), Clyde England - GSAK and James Sherring - ST2GPX

Thanks also to all the sites I've linked to.



Related Information Links

GSAK (Geocaching Swiss Army Knife)

GPS Babel

ST2GPX General Information

Download ST2GPX here

Drag and Drop for Windows - example

Importing waypoints to Microsoft Streets & Trips



Geocaching Along a Route
GPX, KML, EST And ARC File Creation Resources

Markwell's Route Planning: Waypoints Along a Route

Geocaching and Route Planning

Golden Horseshoe Geocachers - ARC Builder

Using Google Earth to Generate Routes For Geocaching

Using Streets & Trips to Generate Routes For Geocaching

Using Streets & Trips to Generate Waypoints For an Arc Filter to Find Caches Along a Route in GSAK

Using Streets & Trips to Generate Routepoints For A GPX File For Use With The Caches Along a Route PQ at Geocaching.com

Using Streets & Trips to Generate Polygons For an Arc/Poly Filter in GSAK


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Updated 2008/04/11
Oh Canada Alberta
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