Saturday, July 12, 2014

Pupil Distance Meter on iOS: new approach for accuracy improvement

Our Pupil Distance Meter (PDM) app is currently available on both platforms Android and iOS. Though  these two apps are named the same they use different methods for PD calculation.

We have listened to feedback from Android users and have updated the app webpage with guide and tips how to improve measurements accuracy. The method used in the Android version is sensitive to measurement conditions and requires proper head and reference position and very accurate rulers adjustment. Although the app does image processing and quick automatic measurements, sometimes it is necessary  to correct rulers position manually.

However the app users tend to use the PDM without browsing the guide and following important tips. For such app lack of attention to the details usually causes misunderstanding of the measurement procedure and inaccuracy in calculations.

Based on Android experience we have come up with a new idea for the PD measurement and decided to implement it on iOS platform first. The main goal of the iOS version of the app is to test a new approach, to improve accuracy and consistency of measurement results and app usability in general.

First version of the iOS app offers manual measurements and requires two different pictures of a face for accurate PD calculations. Although we have tried to automate the process of taking pictures, pupils and a reference have to be accurately marked on both pictures manually. Working with two pictures might take more time for a measurement session but it improves accuracy of the results.

Users are still required to follow the instructions and put some effort into learning the measurement procedure, but it is common for such apps and as soon as they are familiar with the app  good results can be achieved.

As we expected the new method appears to be quite accurate and not so sensitive to the measurement conditions but still is very sensitive to accurate rulers alignment on both picturesSimulation and accuracy test results  are presented on the app webpage where you can compare it with usual ruler measurements.

Based on our tests Pupil Distance Meter app for iOS returns more accurate and repeatable results compared to other apps on the market for this purpose. It also shows big improvement compared to our Android version of the app.

We plan to update the Android version of the app with the new method currently used in the iOS version. Any feedback or suggestions are welcome.

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