I used something like 4 different algorithms in the end to approximate the pixel location. A voting algorithm + smoothing algorithm is also used to find the final pixel location.
What I did to measure accuracy was to draw targets on the screen, and focus my eyes on them. The error the absolute distance from the estimated pixel to the actual target pixel.
To answer your question - on a Nexus 10, there is a expected error of about 0 to 160 pixels radius in office lighting conditions.
As for small movements, I use the full resolution video of 1344xwhatever, which gives a lot more leeway in terms of movements. The movements are then smoothed over time using a moving average over 8 frames, and another smoothing algo uses a pyramid kernel.
TL;DR: lots of algorithm. Quite a number are dodgy.
What I did to measure accuracy was to draw targets on the screen, and focus my eyes on them. The error the absolute distance from the estimated pixel to the actual target pixel.
To answer your question - on a Nexus 10, there is a expected error of about 0 to 160 pixels radius in office lighting conditions.
As for small movements, I use the full resolution video of 1344xwhatever, which gives a lot more leeway in terms of movements. The movements are then smoothed over time using a moving average over 8 frames, and another smoothing algo uses a pyramid kernel.
TL;DR: lots of algorithm. Quite a number are dodgy.