Figure 6. Recognition rate as a function of the number of shapes in
the shape library. Different slant degrees are depicted by lines of
different colors.
of each concavity drops, which reduces the recognition rate.
We also measured the reprojection error for different distances
of the camera from imaged shapes. Figure 7 shows the average
reprojection error over ten different shapes in a distance ranging
between 20cm and 100cm. For most shapes the average
reprojection error was smaller than one pixel when positioned 1m
away from the camera. As can be seen, Nestor has about half the
error of ARToolKit.