[Gpsbabel-misc] extreme simplification
GPSBabel converts and transfers data like waypoints, tracks & routes.
Brought to you by:
robertl
|
From: Vidar G. <vid...@37...> - 2007-05-12 07:57:42
|
I was playing with the idea of using the simplify filter to place one waypoint on a map for each tracklog, to create an inventory of a large amount of tracklogs, which can be used to speed up filtering of files using the polygon or radius filters. Trying this, the following are achieved: -x simplify,count=1 Last location -x simplify,count=2 First and last location -x simplify,count=3 First, middle and last location What is the middle point? Is it where half the distance was travelled, or the halftime position? -x simplify,count=4 Adds halfway to middle location? -x simplify,count=5 Adds middle of first quarter? -x simplify,count=6 Adds middle of second half? Is this correctly observed? Let's say that the GPS unit typically starts logging before a good 3d fix have been achieved (mine does, and this will affect the results from the above filtering), so I'd like to be able to offset the start of each tracklog by a certain sample count, or a given time interval. This is similar to the "-x track,start=" filter, only the time is relative, e.g.: -x track,start=+30s Back to my above tracklog inventory: I'd like to create a GPX file with one waypoint for each tracklog, where the name of each waypoint is the file name of the original tracklog (where the position should ideally be a geometric average, but the endpoint is also useful). This should be feasible using GPSBabel and a bit of shell scripting (or Perl/Python), I think. |