Version 1.7 released: better readings, improved user experience

Version 1.7 recently hit the App Store and the Google Play Store. It delivers guaranteed better readings by enforcing compass calibration, and also allows you to view the map before creating an incident.

Compass calibration

The compass calibration gauge as it fills up by doing the figure-8 motion with your phone.

Prior to taking a reading, the app now ensures that you calibrate the compass. It does this by employing a calibration detector, built using the phone’s gyroscope, to track the phone’s movement. Successful movements advance the needle on a visual gauge. When the gauge is full, calibration is successful, and the phone will vibrate and allow you to proceed with the reading.

Why it matters: the data collection project showed that calibrating the compass had the single biggest influence on the accuracy of headings. Next up was being out in the open (away from cars, buildings, metal fences, …). Keep reading for details.

This table shows the 1-sigma error in different scenarios to show you how much of a difference the calibration movement makes. What is 1-sigma error? The compass error is different for every reading. The distribution of errors (how many errors of a given value are observed when lots of heading errors are collected) are statistically “normal”, which means they look like a typical bell curve when plotted as a histogram. 1-sigma is one standard deviation on the distribution: 66% of the time, the error will be 1x sigma, 95% of the time it is 2x sigma, and 99% of the time it will be 3x sigma.

So, for a “not out in the open” reading (ie, next to a car, near a metal fence) with no compass calibration, the error will be +/- 180° 99% of the time. You literally cannot get worse error than that with a compass.

1-sigma errorNo calibrationWith calibration
Not “out in the open”+/- 60.4°+/- 8.9°
“Out in the open”+/- 36.7°+/- 4.8°
Above data (n=160) combines both Android and iPhone data together. When partitioned, iPhones are slightly more accurate than above, and Android phones less accurate than above, on average.

View the map prior to creating an Incident

Before taking a reading (if that’s your goal), you might want to get some “situational awareness”: see what other people have seen, or what the Alert Wildfire cameras see. It’s now as simple as tapping “View map” on the main screen.

Only once you take a reading will be prompted to create and name an Incident.

What else?

  • The topographical lines on the map are now darker to help you better visualize the terrain.
  • In Settings > Advance settings you can elect to see public readings near the map’s view, instead of only near your location.
  • The post-reading survey is now one question: “Are you out in the open?”
  • Alert Wildfire image viewer shows how old the image is, and continues counting up if the image data doesn’t change.
  • Early results from the data collection project have been integrated into the new triangulation algorithm. Turn on the new algorithm in Settings > Advance settings.
  • Minor bug fixes.

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