The Simplify filter is used to simplify routes and tracks for use with formats that limit the number of points they can contain or just to reduce the complexity of a route.
The filter attempts to remove points from each route until the number of points or the error is within the given bounds, while also attempting to preserve the shape of the original route as much as possible.
The quality of the results will vary depending on the density of points in the original route and the length of the original route.
For example, suppose you have a route from Street Atlas 2003 that you wish to use with a Magellan GPS receiver that only supports up to 50 points in a route:
gpsbabel -r -i saroute -f RoadTrip.anr -x simplify,count=50 -o magellan -F grocery.rte
Maximum number of points in route.
This option specifies the maximum number of points which may appear in the simplified route. For example, if you specify "count=50", all resulting routes will contain 50 points or fewer.
You must specify either this option or the error option.
Maximum error.
This option specifies the maximum allowable error that may be introduced by removing a single point. The value of this option is a distance, specified in miles by default. You may also specify the distance in kilometers by adding a 'k' to the end of the number.
How the error is determined depends on whether the length
or crosstrack method is used. If you are using the length
method, the error is the change in the length of the route introduced by
removing a point. If you are using the crosstrack method, the error is the
distance from the point to the line that results if that point is removed.
Use cross-track error (default).
This option instructs GPSBabel to remove points that have the smallest overall effect on the overall shape of the route. Using this method, the first point to be removed will be the one that is closest to a line drawn between the two points adjacent to it.
If neither this option nor the length option is specified,
this is the default.