<para>
Similar to the <option>crosstrack</option> method, but the error introduced by
removing a point is set into relation to its associated horizontal accuracy,
determined as 6m * HDOP. If there is timestamp information, the distance to the interpolated point between
the two neighboring points is used instead of the distance to their connecting line.
</para>
<para>
The effect of the relative method is similar to a combination of
the crosstrack method with the discard filter: points are removed preserving the
overall shape of the route (track), but preferably those that are unreliable.
</para>
