[talk-au] Running stats against GPX files ...

[John Smith]

--- On Tue, 23/6/09, Graeme Wilson <wanderer55 at live.com.au> wrote:
> Another idea is to have our own proprietry file format
> called .osm I reckon that we could have several lines of
> text at the start to declare things like program version,
> who made the file, the start and end time of the actual
> recording for copyright purposes, the number of lines of
> data in the file, and then the lat and lon to 7 decimal
> points accuracy.

I've been doing some checking into what's possible and it looks like you can compress 20 bytes per point files considerably. The files all contain 2,122 points.

The GPX files my app produces..
247112 test.gpx
12751 test.gpx.gz

Straight conversion using gpsbabel which makes bigger gpx files.
299091 test2.gpx
13519 test2.gpx.gz

20 bytes per point files.
44240 test.raw
  8305 test.raw.gz

Also just as a thought experiment, I thought I'd do a comparison on JSON encoded files, and got the following results.

140877 test.json
  9994 test.json.gz

For those that don't know JSON files are similar to XML/GPX in that they are human readable, but they aren't any where near as bloated and they parse by apps much faster, some think up to 100x faster, than XML files.