I have previously posted about Blacketts Ridge trail, but I hiked the trail again yesterday right after it had rained and got some very nice panoramas. There was snow higher up in the mountains, but unfortunately, the clouds didn’t clear enough to get good pictures of that.
I have been somewhat disappointed with the GPS track information that my app reports. It appears to only capture a new track coordinate about every five seconds. I presume it does this to save on battery power as the GPS consumes a lot. Note, because of this I use an external battery to help my iPhone last longer (the one I bought is less than $10 from Amazon).
However, GPS coordinates are not entirely accurate, so my tracks tend to jump around and they clearly don’t show exactly where I walked. Not only does this look bad in my Google Earth videos, it also gives misleading information as to how far I walked and how much I climbed for a given hike. Thus, I wrote a program to smooth out the GPS track information. This now provides a lot better information as to how much I climbed, and it also makes the tracks better looking. The only drawback is that the distance of the hike is now likely a little short as some of the switchbacks were smooth out a bit and thus won’t be accurately reported.
At any rate, I have now updated all my hikes to show this smoothed track information, though I have not updated the videos (yet).
UPDATE (3/31/13): I knew that Google Earth clamped my GPS data to its terrain map, which is nice because then you can see the track (it’s not hidden under the terrain data in places), but I just discovered that it uses this clamped data when creating its elevation profile. Unfortunately, I had been using the stats on this profile to know how many feet I have climbed.
In my latest hike, the clamping caused a big error when Google thought I had stepped over the edge of a cliff and counted me as having climbed down and back up the 300 foot cliff wall! Because of this, I now calculate climbing information directly from my own data (thankfully I’m a programmer and can do this). So, I will be reporting both how high the highest point on my hike was over the trail head, and then also how many total feet I actually had to climb up (which takes into account that hikes go up and down in places).
I also didn’t like how my smoothed track data seemed to show I hadn’t hiked that far. So I now smooth the data less when calculating the distance in miles that I walked. I think this is a fairer representation of the actual distance of the hike.
UPDATE (4/7/13): I still didn’t like the distance calculation because I was using just a point to point calculation using longitude and latitude only. The calculation didn’t take into account the ramp going up and down, so I’ve added that in now.
And after looking at my elevation data more, I concluded that it needed to be smoothed even more to get an accurate calculation of how many feet up and down I walked.
It would be so nice if the GPS data was more accurate!!
UPDATE (6/10/13): I notice a number of people have dropped by looking for “GPS Smoothing”. If you would like my C# code that I use to do the smoothing, just drop me a message, and I can send you my Visual Studio 2012 solution.
UPDATE (10/5/13): I’ve posted my VS 2012 solution: here. It’s the file GPXTest.ZIP.
I thought I should comment on just how I make my Google Earth videos of my hikes.
Well, on my iPhone, I use the “Gaia GPS” app. Each time I go for a hike, I start a new “track”. These are saved and can then be exported via email as a “.GPX” file which can then be loaded into Google Earth (via drag and drop). However, Google Earth doesn’t load them as separate tracks, so I first edit the file (it’s an ASCII file) and isolate each track putting them into separate GPX files. And also, so that my video doesn’t fly back to the starting point, I delete the GPS info after it reaches the highest point of my hike.
When I drag the GPX file into GoogleEarth, it asks my if I want to create “KML Tracks” or “KML LineStrings”. I’ve been using the LineStrings option as it removes the timing information, since I don’t want the flying to be based on how fast or slow I was walking.
GoogleEarth then creates an object called “GPS device” under “Temporary Places”. I right click on this and select “Properties”. Under “Style, Color” I select the “Share Style” button, and then under the Lines section, I select the color of my line, and set a width of 3. In that same dialog, to the right of the object Name, there is a button where you can select what balloon icon to use. I select “No Icon”.
We are now ready to fly. This is done by selecting the “Play Tour” button at the bottom right of the “Places” panel. But it may not look very good, so you have to select some options. So go to Tools, Options, Touring. I set these options:
Time Between Features: 0.0
Wait at Features: 0.0
Fly along lines: check
Camera Tilt Angle: 75.0
Camera Range: 200.0
And now it flies like in my video, but I need a way to capture the video. Google charges for this feature ($400 for the “pro” version of GoogleEarth), so I instead use a program called Fraps, which is just $37. It also will record whatever music I am playing on my computer.
So I start up Fraps, move the tour play button back to the start, and set up some music. Then I press play on the music, press play on the tour, and hit F9 which causes Fraps to start recording. Once the video stops at the summit, I then used the keyboard to tell GoogleEarth to rotate the scene, and then I hit F9 to stop the capture.
But this outputs a full resolution AVI file, so then I need to convert it to a MP4 file. For this I found a utility called Prism Video Converter, which costs $35. I also use this utility to add the title of the hike at the bottom of the video.
However, when I uploaded the video to YouTube, their software complained about my video and the format options I used. They recommended (among others) that I use Apple’s QuickTime Pro ($30), so I got that and use it to convert my MP4 file to a MOV file.
Note, to get HD quality from Google Earth, you should set the “View Size” to “1280 x 720p HDTV”. YouTube also has a page here, where they list what settings you should use in QuickTime Pro for best results.