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Trimming GPS Tracks With GPSTrackViewer

November 13, 2007


As I've blogged about before, I like to memorialize an especially enjoyable hike with a page that shows some photos connected to the path shown on a Google Map, like the one shown above of a hike on the Emerald Pools trail in Zion National Park. (The page itself is here.)

The software I put together works great, but the problem with that hike was that I was recording the track log all day, and Emerald Pools was only a small part of it. Looking at the whole track log, only the red section was on the Emerald Pools trail:


Here's the red section greatly enlarged; you can see that it matches the map, above:


It took me more than an hour to extract the relevant track points from the whole file. There has to be some software to do this, I thought, but I couldn't find any.

Now there is. I've just finished writing GPSTrackViewer, which you can download for free (if you have a Mac); the link is at left. With GPSTrackViewer, it took me about 5 minutes to pull out the Emerald Pools track points.

Here's another example from last weekend's trip to Western Nebraska, mostly to see Carhenge. (Some photos are here.)

Here's the whole track log. The red section at the top is Carhenge; the red section at the left is a hike to the top of Scotts Bluff.


(For those of you who know Western Nebraska, the two hooks at the bottom are for Chimney Rock and Court House/Jail Rock.)

All it took to isolate the Scotts Bluff hike with GPSTrackViewer was to zoom in, select the track points, mark them, and save the marked points to another track log, which is the one I uploaded to the web page. Here's a snapshot (the page itself and the one for Emerald Pools, above, are interactive):


Note to Windows users: I know some of you will ask about a Windows version of GPSTrackViewer, but there won't be one. I wrote it so I would have the tool I need, which I now have, and to have some fun, which I did. To create a Windows version would be days of work, and by "work" I mean "opposite of fun". Sorry... not this time. (If any experienced Windows programmer wants to create a version for Windows, let me know. Maybe I'll make the Mac source code available. It's not a porting job, but a rewrite. The Mac version is written in Objective-C and C++ for Cocoa; MFC and Visual C++ on Windows are completely different.)

Blog Archives

Photography Articles

Raw Conversion: Better Never Than Late April 24, 2008

Scanning in India by Way of California With ScanCafe February 15, 2008

How To Back Up Your Personal Computer January 30, 2008

Every Camera I've Ever Owned January 25, 2008

Sharpening JPEGs for the Web January 4, 2008

Lessons Learned From My Memory Problem December 20, 2007

Hunting Down a Mac Hardware Problem December 20, 2007

Trimming GPS Tracks With GPSTrackViewer November 13, 2007

The World's Shortest Camera Buying Guide September 22, 2007

Transporting and Storing Portable Backup Drives August 26, 2007

"The Luminous Landscape" Teaches Me to Print August 4, 2007

Creating a Google Photo Map (Revised) June 26, 2007

Sony GPS-CS1: Not Good Enough for Geotagging Photos June 24, 2007

Epson P-3000/P-5000 Multimedia Storage Viewer March 10, 2007

Trying Out Infrared January 20, 2007

Stupid Designs Hold Digital Back April 1, 2006


Other, older articles



A small collection of my best photos (click the image). You can order prints, too.


image ImageIngester
image ImageVerifier
image LRViewer
image LRVmaker
image PhotoSelectLink™
image ImageReporter
image SpanBurner
image GPSTrackViewer


The 2004 2nd Edition, a so-called "update" of the 1985 book, which turned out, not surprisingly, to be a re-write. Covers Solaris, Linux, FreeBSD, and Darwin (Mac OS X).

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