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Create Gpx File From Scratch


shunra

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Can anyone help me with the technicalities of the following?

 

In the framework of solving a puzzle cache, I have a list of 8 digits, which must fit into the following mould:

 

N 48 0A.BCD

W 122 4E.FGH

 

At one of these, the prize cache is hidden. I believe I can infer the correct combination by way of elimination, but in order to do that, I need to be able to load these into my GPS, and into MapSource.

 

In order to remain within the GPS memory limitations and in order to have less redundant information on the MapSource map, I decided to crop off the least significant digits D and H from the waypoints, and then to eliminate the duplicates, and allow for a wider search radius. Moreover, I can always add possible significant digits to individual waypoints again at a later stage.

 

But how do I make all this into a GPX file?

 

I have experimented with it a bit, but somehow the conversion into decimal degrees and back produced entirely unsuitable waypoints. Does anyone have a good idea how to go about this?

 

Thanks!

Edited by Shunra
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When I have to do this, I do the lazy thing and use a file format that I know uses DD MM.MMM, edit it by hand (or sometimes a program) and then feed it to GPSBabel and let it write to GPX or Mapsend or Mapsource or whatever. (This probably falls into the category of making everything look like a nail...) For example, I know the GPSUTIL format uses the right format, but multiplied by 100. So I'd create a file of waypoints:

One      4800.000N 12240.000W 0000000m Point one                        c
Two      4801.000N 12240.000W 0000000m Point two                        c
Three    4802.000N 12240.000W 0000000m Point three                      c
Four     4803.000N 12240.000W 0000000m Point four                       c

(the first field is waypoint name, the numeric formats are the exact ones that geocaching.com uses, but with the decimal moved. the altitude almost never matters, and 32 pointsof waypoint comment is availble. The "c" is "default icon".

 

Then you can toss that to whatever format you like:

 

gpsbabel -i gpsutil -f yourfile -o mapsourcce -F xxx.mps -o gpx -F xxx.gpx -o gpsutil -F -

 

will create a mapsource file, a gpx file, and show you the file back on your screen so you can verify you got all the columns aligned correctly.

 

It sounds a little nerdy, but it's still a lot easier than crafting GPX by hand. This basic idea is how I enter parking coords and such from cache pages...

 

And as to your new request of duplicate suppression based on position, GPSBabel can do that, too. Use the "-x position,distance=100" before the -o option and only waypoins more than 100 ft apart will appear in the output.

Edited by robertlipe
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