In this chapter, we've covered quite a bit: talking to your gyroscope, using that to find unknowns, negating the effects of camera shake and rolling shutter.

We started out by creating an Android app that uses background tasks to initiate recording media into a video file. While doing this, we figured out how to extend OpenCV's camera view class to incorporate custom UI and responsiveness. With this, you can now create very sophisticated UIs with an OpenCV backend. Along with this, we also captured the gyroscope trace and stored it in a single file. The sampling rate of the gyroscope and the media were different – however, we did not care about it at this stage. We'll let the app store a higher density of gyroscope traces (every few hundred microseconds versus every few dozen milliseconds for the media).

Once we had the media/csv pair, we used Python and the numpy/scipy libraries to calibrate the system. We had three unknowns initially: the pixel focal length of the camera, the gyroscope...