Figure (a) shows the three-dimensional surface reconstruction of the outer
western rim of the lunar crater Copernicus, obtained by the technique of
selecting a shape from shading solution consistent with shadow analysis in a
first step and taking into account the detailed shadow structure in a second
step. The shading image alone does not reveal the large-scale eastward slope
of the profile, which can only be derived from the shadow image. Reconstruction
is based on the images acquired on September 30,
2002 and on January 12, 2003. Effectively,
the shadow allows for adjusting the albedo such that the shape from shading
algorithm yields a surface profile consistent both with the small-scale altitude
variations evident in the shading image and the large-scale slope derived from
the shadow image. In (b) the inner eastern rim of Copernicus is shown. The
surface profile reveals terraces and small craters in the crater wall; the
performance of the reconstruction algorithm is slightly decreased by small
shadows in the shading image cast by the central peaks. The correspondence of
the simulated shadow shape with its real counterpart is reasonable.
