Map not showing all data points

Tracking System
#1

I’m working on an application using a Tracker One and have run into a problem. The application requires fairly precise tracking at low speeds (think walking speed) over a relatively small area (<1 mile radius).

I’ve set the Tracker with Radius Trigger = 0, Minimum Interval = 0, and Maximum Interval = 10 sec. This should give me a location event every 10 seconds. Once configured, I can confirm that this is working by watching the EVENT log – I get a location event every 10 seconds.

Then I go for a walk around my cul de sac to capture data. When I return and look at the map, I seem to be missing data points. At an average walking speed, I should see a data point at about every 10-12 meters – and I don’t. Also, the map shows a number of circles with a number in it – I am assuming those are data points that have the same lat/long values. That should never occur as I am moving constantly at a walking pace.

How can I fix this to show all of the data event data on the map?

#2

I believe you are getting multiple points with the same latitude and longitude because the GNSS is losing lock while walking. How are you carrying the Tracker One? The GNSS antenna is directional and faces up, that is to say the side of the enclosure with the LEDs should face the sky.

#3

Hmm. I’m holding it out in front of me with the device face up – so shouldn’t be losing the GPS lock…

#4

In the console map view, the historical data will show all of the actual points, but nearby points are “folded” into a single point with a count on the map. It’s currently set to a 25 meter distance for folding, and the point is at the average. Since the GNSS coordinates will drift a bit even while stationary, this makes the map values more usable in most cases.

However, it may not be helpful in your walking case. Unfortunately it’s not currently configurable, but it’s something we can consider.

Note that the underlying data is correct, so if you are monitoring the event data or querying the API for location data, you’ll get the actual location, not the folded location.

#5

Ah that makes sense.

It’s probably important or Particle to understand that not all tracking applications are for vehicles. Pedestrian, pet, and other applications will easily be inside a 25 meter distance from sample to sample and the mapping app in the console should be configurable to reflect those use cases.

Is there an easy way to read the location events and then convert them into a Google Earth (.KMS) file format (another shortcoming in the console offering)?

K

1 Like
#6

Can you share the algorithm for GPS coordinate folding? I’m curious to use it to clean up my maps.