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Author Topic: Capturing complex boundaries in gpx format  (Read 6082 times)

wilderness.webmaster

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Capturing complex boundaries in gpx format
« on: December 03, 2010, 02:10:17 PM »
I'm in the process of creating Garmin compatible maps of wilderness areas by state (see California Wildernesses, which is the first state that I did), but I also want to provide a more universal option for people who don't have Garmin units or to use for other purposes. So I thought about using gpx.

Here's the dilemma though: Wilderness boundaries aren't really tracks or routes and they're large  and complex enough geographically that generalizing them to any significant degree results in too much loss of detail. Ungeneralized boundaries, however, contain thousands of points and, as I discovered when I tried to transfer a test file to my GPS unit (gpsmap 60csx), units truncate at 200-250 points. So I created the attached file that breaks a single boundary into multiple routes, each with less than 200 points. This file is of the Rattlesnake Wilderness in western Montana.

Is this the best format for maximum compatibility with a variety of GPS units and other devices?
Lisa Eidson
Wilderness Information Specialist, Webmaster
http://www.wilderness.net [nofollow]

jbensman

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Re: Capturing complex boundaries in gpx format
« Reply #1 on: December 04, 2010, 09:36:20 AM »
Don't use routes-use tracks.  Most newer GPS can handle way more than 250 track points.  Having it broken down would cause problems such as having to enable each track.  So I would make them gpx files with one trak.

However converting shapefile polygons to gpx can not work right if there is an internal boundary. You can get extra lines that are a pain to deal with.

Boyd

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Re: Capturing complex boundaries in gpx format
« Reply #2 on: December 05, 2010, 05:44:55 AM »
Also depends on your intended audience. None of the Garmin Nuvi series can import tracks. Only some of them can import routes. But all of them can use .img files...

wilderness.webmaster

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Re: Capturing complex boundaries in gpx format
« Reply #3 on: December 07, 2010, 10:27:07 AM »
We are definitely going to strip out any internal geometry (donut holes such as inholdings) so that shouldn't be a problem. I did try importing this boundary as both a route and a track onto my gpsmap 60csx and it truncated both at 250 points. Even if I set the map page to show the maximum number of track points (10,000), it still truncates imported tracks. I'm guessing that there's a difference between the number of track points you can actually log on the unit (quite large) versus the number of track points you can import to your unit (250 or less/track). Can anyone verify this?
Lisa Eidson
Wilderness Information Specialist, Webmaster
http://www.wilderness.net [nofollow]

jbensman

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Re: Capturing complex boundaries in gpx format
« Reply #4 on: December 07, 2010, 11:40:17 AM »
I had a 60csx many years ago and remember that limitation on 250 points.  If I remember correctly, if you save your current track or archive it on the GPS, it also cuts it down to 250 points.  ut I am not aware of any newer GPS that has this limitation.  I have downloaded countless track files in GPX with more than250 points.  I've never seen anyone break it down before either.

manumuskin

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Re: Capturing complex boundaries in gpx format
« Reply #5 on: October 04, 2011, 05:11:36 AM »
I am a new member and just found this site by googling "wilderness areas gpx"  I have the entire kmz file from wilderness .net and it does work in google earth though it slows it down a bit.What I want is the file in gpx so I can see the boundaries on topo maps i use on topofusion pro.Your Rattlesnake Wilderness area is awesome.If I have to do as your doing and do each wilderness area separate I will but I'd like to know how you did it?I can,t even find a program that will convert kmz to gpx in waypoints let alone tracks.gps babel will do kml to gpx but my file says kml but it is really kmz and gps babel does not recognize it.
If I can figure out how to make the boundaries in gpx file and you want some help doing all the areas I can help.I'm patient and good with maps,gps and most software.Right now all I know to do is switch google earth to the old black and white aerials so I can painstakingly trace the same boundary in topo fusion then then make that a track and then switch to topo.a very long and not very accurate process.I can take the long but not the inaccuracy.
Al

manumuskin

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Re: Capturing complex boundaries in gpx format
« Reply #6 on: October 04, 2011, 05:25:38 AM »
I just figured it out,thanks anyway,I know you would help.I am going to do all the wilderness areas and when I get done I will post it and anyone who wants the files can have them.
Al

babj615

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Re: Capturing complex boundaries in gpx format
« Reply #7 on: October 04, 2011, 07:02:43 AM »
I just figured it out,thanks anyway,I know you would help.I am going to do all the wilderness areas and when I get done I will post it and anyone who wants the files can have them.
Al

Will this help?

http://www.mcrenox.com.ar/downloads/ge2gpx.exe
Garmin GPSMap 60cs, Dakota 20, Colorado 400t, Oregon 300/400t/450/550t/650/650t, Montana 650, Lowrance Endura Sierra, nuvi 3790, iPhone 3G/4/4s
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wilderness.webmaster

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Re: Capturing complex boundaries in gpx format
« Reply #8 on: October 05, 2011, 08:31:30 AM »
Hi Al,
I'd definitely be interested in seeing your final product once you get the gpx files converted. I'm the webmaster for wilderness.net, so I'm glad you've found our KMZ files useful. If you have a Garmin GPS that will read maps, we also have the same boundaries available for download that way at http://www.wilderness.net/GPS/ [nofollow]. With respect to GPX though, I'm having my GIS person work on a script to export to GPX straight out of ArcGIS for either a selection or for all 757 wilderness areas at once. That way each time I update our data, which is frequently, I won't have to do these by hand. Please contact me once you have your conversions done so I can look at them: [email protected] Thanks!
Lisa Eidson
Wilderness Information Specialist, Webmaster
http://www.wilderness.net [nofollow]

Boyd

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Re: Capturing complex boundaries in gpx format
« Reply #9 on: October 05, 2011, 09:25:42 AM »
If you have a Garmin GPS that will read maps

Unfortunately Al is a Magellan Triton die-hard.  ;)