The figures depict side and top views of a foliation of
RP^3 by circles. More precisely, several left cosets in SO(3) of
the isotropy group H of (0,0,1)^T are displayed.
The fibers lie in the ball with center (0,0,0) and radius \pi,
with antipodal points on the boundary identified. The colors on
the fibers indicate the distance from the origin; the dots indicate
intersection with the plane y = 0. Note that the fibration
S^1 -> RP^3 -> S^2 is double covered by the Hopf fibration
S^1 -> S^3 -> S^2. The detailed structure present in the figure
(such as the overall z-axis symmetry, the fibers lying in planes,
and the the double cosets H\SO(3)/H comprising nested tori)
is explored in detail in the article by Rick Kreminski in