Smoothing data received from CoreLocation

Question

I'm trying to develop an app which allows you to walk around, and where you walked will be drawn on a map. I have this all working fine, but I'm finding that even with a reasonably accurate GPS location the points still jump around a bit. When drawn on a map this has the effect of creating a squiggly or zig-zag line.

I'm looking for suggestions/strategies on how to smooth the data, so that the line drawn on the map is more of a smooth best fit, rather than an accurate point to point drawing.

Answer 1

There are many different types of smoothing algorithms you could apply to the data (for a few starting points, see this Wikipedia article). The only way to know for sure which is/are suitable for your application is to implement and test them.

Simple or weighted moving averages are fairly common (taking the last n samples and averaging them), but have the problem of lagging behind the data. A common one for filtering signal noise is a high-pass filter, which attenuates small (noisy) movements while passing through larger ones. Apple has some code for this in their AccelerometerGraph sample.

I'd suggest trying those out first as they're easy to implement, before looking at the move complex ones.