This figure shows 3D surface profiles of selected regions obtained by
shadow analysis only (without shape from shading) based on multiple pixel-synchronous
images. These examples show that shadow analysis enables us to reconstruct
features at the limit of image resolution, for which photoclinometric approaches
are hardly suitable. Figure (a) shows the region between lunar craters
Hesiodus and Wolf, viewed from the north-east. The result is based on an
evaluation of two images taken on April 21, 2002,
and on September 30, 2002. Very shallow slopes
of the mare surface around the mountain chains which amount to a few tenths of
a degree are revealed by bidirectional shadow analysis. Figure (b) shows
the eastern face of the Montes Recti mountains along with very shallow
ridges of 160 to 180 m altitude, viewed from the east. Reconstruction is
based on images obtained on September 30, 2002,
and on January 12, 2003, respectively. Figure
(c) displays the reconstruction result for the interesting crater Reinhold
B, viewed from the south-west, obtained with two images taken on September
30, 2002, and on January 12, 2003. Although
the crater floor looks flat, shadow analysis reveals that the altitude
difference between the ridge of the eastern (right) crater rim and the
centre of the crater floor amounts to 1000 m and is thus 700 m larger than
the altitude difference between the ridge of the western (left) rim and
the western part of the crater floor, while the ridges of both rims are
300 to 400 m above the level of the environment. This means that the western
part of the crater floor is on about the same level as the environment,
while its central part is 700 m deeper. Hence, the western half of the
crater floor is inclined by an angle of approximately 4 degrees, given
the crater diameter of 19 km. Figure (d) shows a cross-section of Reinhold
B which additionally contains the results of shadow analysis obtained with
a third image (June 09, 2003) obtained at
again different illumination conditions (points marked by "a"). Here, an
identical ground level east and west of the crater has been assumed.
