Magellan DirectRoute 3.0 Manual de usuario descargar pdf (Pagina 94)

Da-

Fil-

ters

Example 4.1. Using the polygon filter

Suppose you have a polygon file that defines the border of your county, called mycounty.txt. This com-

mand line will give you only the points in your county:

gpsbabel -i geo -f 1.loc -x polygon,file=mycounty.txt -o mapsend -F 2.wpt

Example 4.2. Using the polygon and arc filters to find points in or nearly in a

polygon

Because the polygon and arc filters use the same file format, you can use them together to find all points

that are "in or nearly in" a polygon. This can be useful if your waypoints or the boundaries of your polygon

are not quite perfect, so you want to provide a buffer zone around it in case there are points nearby that

should be in the polygon but aren't quite.

gpsbabel -i gpx -f points.gpx -x stack,push -x polygon,file=mycounty.txt

-x stack,swap -x arc,file=mycounty.txt,distance=1k -x stack,pop,append

-x duplicate,shortname -o gpx -F nearmycounty.gpx

This command makes a copy of the points, finds the ones that are in your your county, swaps that result

with the copy of the original set of points, finds the ones from that set that are within 1 km of the border

of the county, puts the two lists together, and then filters out any points that appear twice (This step is

necessary because points inside the county but near the county line will be kept by both the polygon and

the arc filter.)

file option

File containing vertices of polygon.

This option is required.

This option specifies the name of the file containing the polygon to use for filtering. The format of the

file is as described above.

GPSBabel supports converting any route or track to a file usable by this filter; simply read it in the normal

way and write it using the arc file format. Afterward, you will need to make sure that the first point and the

last point in the file are the same, as the polygon filter depends on that. You can do so with any text editor.

exclude option

Exclude points inside the polygon.

When this option is specified, the usual sense of the polygon filter is reversed. That is, points that are inside

the polygon are discarded while points that are further away are kept.

Include Only Points Within Distance of Arc

(arc)

This filter keeps or removes waypoints 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.

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Magellan DirectRoute 3.0 Manual de usuario Pagina 94