-
-
- <para> The arc filter is designed to include points based on
- their proximity to an arc, which is a series of connected
- line segments similar to a route or a track but without any
- associated data other than the coordinates.
-</para>
- <para> The arc is defined in a file whose name must be
- provided with the <option>file=XXXX</option> option to the filter.
- That file contains pairs of coordinates for the vertices of
- the arc, one coordinate pair per line. Comments may be
- included by preceding them with a '#' character. An arc file
- looks something like this sample:
-</para>
- <screen format="linespecific">
-# Lima Road/SR3 north of Fort Wayne, Indiana
-41.150064468 -85.166207433
-41.150064468 -85.165371895
-41.149034500 -85.165157318
-41.147832870 -85.164771080
-41.146631241 -85.164384842
-41.144270897 -85.163655281
-41.141953468 -85.162882805</screen>
- <para> An arc file may optionally contain gaps in the arc. You can
- specify such a gap by inserting a line containing "#break"
- either on a line by itself or after the coordinates of the
- starting point of the new arc segment.
-</para>
- <para> In addition to the file containing the arc, you should
- also specify the maximum distance from the arc that will be
- accepted; that distance is declared on the command line with
- the <option>distance=X.XX</option>
- option to the filter. Distance options may be expressed in
- miles (<option>distance=3M</option>) or
- kilometers (<option>distance=3K</option>). The default is
- zero miles. You may also specify the exclude option, which
- causes GPSBabel to only include points that are further than
- the specified distance from the arc.
-</para>
- <para> For example, assuming the arc above is in a file called <filename moreinfo="none">lima_rd.txt</filename>:</para>
- <screen format="linespecific"> gpsbabel -i geo -f 1.loc
- -x arc,file=lima_rd.txt,distance=1 \
- -o mapsend -F 2.wpt</screen>
- <para> would include only points within one mile of the
- section of Lima Road covered by the arc.</para>
-