How to #unzip a #KMZ file


Screenshot of my KMZ file

In this tutorial, I showcased how to unzip a KMZ file.  Here is the video:

The significance of this tutorial, if you recall from my Part 2 of Capture Your Tracks , when I was not sure as to how much accuracy was actually captured by the application.  It took me a few weeks to ponder, while I worked at my day job (sorry boss…but you can’t do much about my imaginations of GIS fascinations…).  I recall that the elevation and travelling speed outputs were quite live, and even when you “Record” there is a live moving average read out.  So I concluded that while the individual points were not shown, like my NovaTel GPS unit (that’s Canadian made eh), My Tracks was still capturing the data.

So if I have you completely lost, we are talking about the data I collected in my Google Drive, when using My Tracks offered by Google for Android.  Where I did Part 1 Capture Your Tracks (and part 2 is in the link in the paragraph before).  Using the KMZ file uploaded to Google Drive using the App’s export tool, I wanted to learn more about the file.

So now you’re caught up, let’s look at the image that I uploaded in this blog entry.  Now, I’m not a fan of how un-formatted the file was, but it still gives a lot of information.  In the first few lines, you have the commentary section, giving some information on the version, how it was captured, name of author.  Following that, you have what are markers and the kml code pointing to images in the Google Earth installation, so you can have the graphical display of your start and end of data capture.  You arrive to three lines then a break and then it continues.  This is where I paused the Record function then resumed data collection (partly because with running this application and recording my tablet, my tablet was struggling). * Ahem* that’s also the reason why the audio went out a few times, its the tablet processor struggling.  I did take the Power Saver Mode off, but even then, the tablet was struggling to video capture the screen while I was running My Tracks.

So this continuous section of data shows us a few things.  1) It shows the datetime information.  2) Elevation, denoted in notation like “504z” which I can only assume is meters above sea level, z being the z axis. 3) You have the coordinates, x and y.


KMZ file showing x, y, z coordinates as well datetime

Now you’ll also notice that the intervals are almost every second.  If you recall, prior to recording the video, I made my settings really fine so that I can capture the most data possible (that’s also probably why my tablet was complaining while I was recording the video).

As we follow the file, there is a section for the speed.  You’ll also notice the name label (“<gx:SimpleArrayDataname=”speed”, we also have bearing and accuracy.


KMZ file with speed, bearing and accuracy.

At the end is something really cool.  The program wraps up and write the last bit of information that really optimizes the Google Earth experience, which is the total distance, the moving time and ect.  When you import this into Google Earth it presents itself as a little info bubble on Google Earth.


KMZ info on distance travel and commentary information displayed in Google Earth.

All-in-all, I was quite satisfied within using My Tracks, my ignorance prematurely got me.  Just reviewing the data, once you unzip the KMZ, you can really see this My Tracks application capture A LOT OF DATA.  It’s really cool.  Now, I’, not sure how much accuracy the data holds.  I guess, my next thing to think about while I’m sitting at my day job (sorry boss) is what the accuracy values represent.  And what the bearing values mean.  In my capture, Accuracy was represented in a double format ranging from 3.9 to 9.0.  Bearing bounced around from 101.0 to 106.0.

So thanks for reading my little fun experience with how to Unzip a KML files and really interpreting the output from My Tracks.

If you found the video interesting, be sure to LIKE the video, it really helps other YouTubers find the video.  I’ll see you in the next video!