On the top
row, we show again the two images

${\mathcal{I}}_{k}$,

${\mathcal{I}}_{k+1}$ from Figure

4 along with computed optical flow
vectors (blue segments) for a sparse set of points (a few epipolar lines are
also shown in

${\mathcal{I}}_{k+1}$). In both of these images, the yellow square
around a point is proportional to the point's estimated scale factor (10 scales

$S=\{1,{0.9}^{-1},\dots ,{0.1}^{-1}\}$ have been used). On the bottom row, we show
the estimated scale factors for all the points in region

$\mathrm{\Psi}$,
as well as the corresponding optical flow magnitudes at these points. Regarding
optical flow, two results are shown: when using 10 possible scales

$S=\{1,{0.9}^{-1},\dots ,{0.1}^{-1}\}$,
as well as when using just one scale

$S=\{1\}$.
As expected, in the latter case, the estimated flow is quite noisy, since the
algorithm fails to produce exact optical flow for points that actually undergo
a large change of scale. We note that darker pixels (in a grayscale image)
correspond to smaller values.