Author Topic: ACA GPS files on Google Earth problem  (Read 1144 times)

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Offline tbone

ACA GPS files on Google Earth problem
« on: December 01, 2013, 10:50:26 pm »
I'm trying to get maps with elevation profiles of some ACA routes. I've tried to do it for the Western Express on  Google Earth, but I'm running into a couple problems.

First I tried using the ACA GPS files. With the files for Sections 1 and 4, all the waypoints appear, but only the first 90 miles or so of the route and elevation profile is shown. With Section 2, it seemed to map the whole route and give an elevation profile, but the distance it shows is only 300 miles, much less than the ACA says it is. With section 3, waypoints appeared, but none of the route was shown.

I then tried using the kmz file from tsteven4.qwestoffice.net. That displayed the entire route, but the "show elevation profile" option is grayed out.

I looked at gpsvisualizer, but that doesn't display the map and profile on the same page, and its profiles often show discontinuities. I thought there might be a way to do it in Google Maps, but I haven't found anything.

I've got the latest version of Google Earth. Any ideas what I might be doing wrong?

Offline mdxix

Re: ACA GPS files on Google Earth problem
« Reply #1 on: December 03, 2013, 09:09:01 am »
I'm trying to get maps with elevation profiles of some ACA routes.
Your best bet is to use the paper maps published by ACA. They include an elevation profile.

First I tried using the ACA GPS files.
This is one  way to get a general idea about the elevation profile. Once you have the GPX file, load it onto your favorite web site tool such as Ride with GPS or GPSies. Both sites will show you the elevation profile and total elevation gain.

The accuracy of elevation data generated on web sites is frequently disputed and vary greatly by web site. I have seen it vary by 50% when calculating the elevation gain. Nevertheless, the profile can give you a general idea about the route.

With Section 2, it seemed to map the whole route and give an elevation profile, but the distance it shows is only 300 miles, much less than the ACA says it is.
This is expected. The GPX file posted on the ACA web site (at the time of this post) is a general representation of the route. It has a series of route points that could be > 10km apart, connected by a straight line, instead of exactly following the route. Therefore, the straight line is expected to be shorter than the meandering actual road.

Offline tbone

Re: ACA GPS files on Google Earth problem
« Reply #2 on: December 03, 2013, 04:26:28 pm »
I'm planning to buy ACA maps. I've been trying to use Google Earth to help in my decision as to whether to go from the west coast to Estes Park, CO via the Transam, Lewis & Clark to Transam, or Western Express to Great Parks South. My plan was to make that decision and then buy the appropriate maps.

Thanks for the explanation as to why the distances on Google Earth don't match those shown on the ACA website. I didn't expect the difference to be as great as it is.

Do you have any idea why when I enter ACA data into Google Earth, it displays all the waypoints, but for some sections it displays only about 1/3 of the route (for example, WE 1 and 4) while for others it displays the entire route (WE 2 and 3)?

Offline tsteven4

Re: ACA GPS files on Google Earth problem
« Reply #3 on: December 03, 2013, 07:33:02 pm »
With any of the routes from tsteven4.qwestoffice.net you can look at the elevation profile one section at a time by selecting the section in the Places panel, right clicking, and selecting "Show elevation profile".

If you pass the kmz file to gpsvisualizer it will show an elevation profile for the entire route, BUT it assumes the sections are sequential.  This is almost never true with the ACA routes.  For example, west of Austin NV there are two choices of the route.  This leads to discontinuities and incorrect distances.

As regards to your decision all the choices are great.  The WE is the most serious (but an excellent route), in the summer it can be quite hot and the distances between places where you can get water is often a days ride.  Another possibility is a combination of the Northern Tier and TransAm, see http://tsteven4.qwestoffice.net/gallery/index.html?albumid=5769994076092330785&si=1
I think I posted more detailed route descriptions of this on this site.

Offline mdxix

Re: ACA GPS files on Google Earth problem
« Reply #4 on: December 03, 2013, 09:32:24 pm »
Here is a sample file of GPX track of Section 1. Import that into Google Earth. It should work. Remember that the distance is still not the same.

I followed these steps to create this file:
  • Edited the original GPX file from ACA to remove all Waypoints. Only the Routes remained. This is because Waypoints are irrelevant to the Route.
  • Edited the file from Step 1 above to merge all the Routes into one route. This is to make sure that the track is rendered in the correct order.
  • Converted the file in Step 2 above from Route to Track using GPSies web site
Voilà.

Do you have any idea why when I enter ACA data into Google Earth, it displays all the waypoints, but for some sections it displays only about 1/3 of the route (for example, WE 1 and 4) while for others it displays the entire route (WE 2 and 3)?
Not really. I can only take a guess.

The original GPX file from ACA was created with a very different purpose in mind using Garmin software to use on (mostly Garmin) GPS devices. It has much more data than a basic KML file would contain. It seems that Google Earth struggled in converting the GPX file into the KML format it needs.

Tracks, meanwhile, are a simpler format that maps more closely to KML. That seems to have done the trick.
« Last Edit: December 03, 2013, 09:34:21 pm by mdxix »

Offline tbone

Re: ACA GPS files on Google Earth problem
« Reply #5 on: December 03, 2013, 11:22:40 pm »
That does exactly what I want. Thanks for the information.