Sunday, May 24, 2015

Geotagging III

This is a two part blog post. Be sure to read both parts.

Part I

Well, not exactly geotagging. Finally I found a camera that does a satisfactory job of geotagging on its own.

But I'm still into logging my location, particularly on trips. For example on a recent trip to Italy I created several maps (here's one).

From my previous research into geotagging I had concluded:
...if you have an Android phone? Don't even bother.
But I've changed phones since then so I thought I'd give Android another chance.

You'll remember that Google "spring cleaned" Google Latitude. But you can still get location history from your Android phone. From a geotagging/geotracking perspective that's what you want.

So I did an bake-off.

I compared Google Now location history to GPSLogger for Android (on my 2013 Moto X) to GPSLogger for Blackberry (on a BlackBerry Bold).

This GIF compares the tracks from all 3 tools.

There are a couple of conclusions. First Google Now's location history is pretty good. However it seems to have it's own mind about when to take a GPS fix. It increases its frequency when it determines that you're moving and slows down when you stop. But the result is that if when you start moving shortly after a fix it may be 5 minutes or more before it takes another fix. I believe that that results in the odd "jumps" in the Google Now location history.

On GPSLogger for Android I have the fix frequency set to one minute. This results in less of those odd "jumps" but they're still there.

I have no explanation as to why both Google Now and GPSLogger for Android indicate that I traveled to the I-55/I-69 junction near the bottom left of the map. One can only surmise that the GPS processor in the Moto X is not very good. But I don't think that this is particular to the Moto X. My previous efforts with GPS logging on Android were on Samsung Galaxys and they had the same results.

Once again GPSLogger for BlackBerry blew away the other alternatives. As I said in my Geotagging II post:
a BlackBerry is a first class method to geotag your photos.
For full disclosure I had GPSLogger for BlackBerry set to take a fix every 30 seconds. This is a remnant from my geotagging efforts. I believe for simply recording a track of travels that every 60 seconds is more than sufficient. Obviously this will reduce the battery impact on the BlackBerry.

Part II

This has continued to bother me. Today when I was driving (actually stopped at a light) I looked at the screen for GPSLogger.

It's getting my location from cell towers. Why? GPS Test was getting 21 satellites!

Why wasn't GPSLogger using them?

I had Android's Settings / Location / Mode set to "High accuracy." (screen capture taken later)

But wait. Read the description for "High accuracy." It says "Use GPS, Wi-Fi, and mobile networks to determine location." "(M)obile networks" means "cell towers" to GPSLogger.

So it looks like "High accuracy" isn't really high accuracy. KitKat seems to be preferring the lower battery impact of cell towers over GPS accuracy.

When I set Android's "Location mode" to "Device only" (GPS) look at the result from Google Now.

Notice the "jump" that I highlighted at 9:03AM. And there are a couple of similar ones to the left (earlier). The track tightens up after 9:03AM. I turned on "Device only" at 9:06AM. Those "jumps" are apparently the result of using cell towers with improper location signatures.

Could that really be it? So I Googled for a while and found this.
if i use 'device GPS only' it works fine. widgets and weather data are correct within a few feet. in High Accuracy mode it tends to put me in the wrong place. often another state or country, or it shows my current location as the location of a cell tower (and GNow tells me i'm like 20 mins from home when i'm already there). in this mode, it seems to never use GPS radio at all, relying entirely on wifi and cell towers. this wasn't always part of the location settings, it just showed up with the update.

So I went to the GPSLogger web site and found this feature.
Selectively choose network, gps and passive location providers
Then back to GPSLogger and Performance / Location Providers.

So I unchecked "Network" and "Passive."

Now look at the result.

I realize that this is a pretty coarse view so here's a zoom in at one location.

Pretty good.

This seems to have significantly improved Android's GPS tracking. It certainly will have an impact on battery life though. Time will tell.

My thinking is to leave Android's "Location mode" to "High accuracy." Generally that works good enough for Google Now's Location History. And I'm going to set GPSLogger Performance / Location Providers to "GPS." That way I'll get more precise logging (and more battery impact) when I want it.

Thanks to for their online animated GIF tool.

1 comment:

Anonymous said...

are you aware, that GPSLogger II (for BlackBerry) exits now also as Andoid application?