Bivouac.com   Home     Help   Index     Login
Why do I have to trace my raw gpx file #20 Back to List   Review Date:2017.01.16

I am frequently asked why it is necessary for authors to manually trace a gpx file. Why can't Bivouac do it automatically? The main reason is that when you make Bivouac waypoints with Draw and Save, your trip is indexed. For example, if you went up 4 different peaks, your trip would be indexed under all of them. Another reason to use GMap is you can label critical points.

Bivouac DOES allow you to view the raw gpx file on GMap. Any trip report with a gpx file will display a link called "View Raw Gpx". But it works by a different mechanism than the waypoints. It directly displays the gpx file, and this mechanism doesn't have the ability to display the Bivouac Peaks, trails, etc.

  1. Get some labels
     The first reason for wanting separate waypoints is to get authors to label a few of the key waypoints. Eg: "we parked here". By using the draw and save function, the author can label the location of parking spots, camps, key intersections, summits.

  2. Thin and correct the points
     A second reason we don't use the raw gpx directly is to make sure there are not too many points. When you search for a trip report close to a given peak, the system has to work it's way through all the waypoints of any nearby trips, to see if they are close enough. A raw gpx file often has hundreds or even thousands of waypoints, depending on the GPS interval.

  3. Why not thin automatically?
     There are in fact bivouac routines to thin waypoints, but they can't do as good a job as a human.

  4. Manual Adjustment
     Raw Gpx files often require manual adjustment where the reception was bad. For example, on my most recent trip up Magnesia creek, I had a raw gpx, but in numerous places the reception wasn't good enough. When I traced it, I was able to correct the problems.

  5. Gpx file in fragments
     Another common problem is that the gpx files might be in several fragments. Or the author might have forgotten to turn the GPS on till they were already underway. Or forgot to turn it off till a few km down the highway. The manual procedure allows any problems like this to be fixed.

  6. Simplicity
     The simplest way to both thin and label waypoints is via the "Trace" mechanism on the GMap. In theory you could try and thin by hand, have a mechanism to insert missing parts of the track, and combine multiple fragments of the track, and eliminate unnecessary waypoints, etc. it would be complex and plenty would go wrong.