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Fig. 8.7
Three-dimensional reconstruction of the eastern half of lunar crater Theaetetus based on
the initialisation of the shape from shading algorithm by shadow analysis according to Sect.
5.2.3
.
(
a
)The
two upper images
are evaluated with respect to shadow, the third one with respect to shad-
ing. The reconstructed surface part is marked by a
white rectangle
, respectively, the corresponding
simulated images are shown
to the right
.(
b
) Surface patch between the two shadow lines (
hatched
)
along with the initial surface profile derived from shadow analysis. (
c
) Section from Lunar Orbiter
photograph IV-110-H2, shown for comparison. Image credit: NASA/USGS. (
d
) Reconstructed sur-
face profile. Although the marked ridge is hardly visible in the three ground-based images used for
surface reconstruction, it clearly appears in the reconstructed surface profile due to its effect on
the shadows. (
e
) Further ground-based image of Theaetetus shown for comparison, not used for
reconstruction, along with the simulated image derived from the reconstruction result. The ridge
crossing the crater and the low central elevation are marked by
arrows
.(
f
) Three-dimensional re-
construction result obtained with traditional shape from shading, selecting the solution consistent
with the first shadow image. None of the previously mentioned details on the crater floor is visible
on the crater floor no data are available. No small-scale structures appear on the
crater floor. The LOLA DEM in Fig.
8.8
b shows a hint of the central elevation of
the crater but no details on the inner crater rim due to the presence of broad interpo-
lation artefacts. In the DEM shown in Fig.
8.7
d obtained with the combined method
of Wöhler and Hafezi (
2005
) based on shadow and shading features, the size of the
central elevation is somewhat overestimated when compared to the LOLA DEM and
the GLD100 (cf. Fig.
8.8
c). Both the LOLA DEM and the GLD100 clearly show
the ridge in the northern part of the crater floor (cf. arrow in Fig.
8.7
d). The overall
crater depth according to Fig.
8.7
d is in good correspondence with the depths indi-
cated by the stereophotogrammetric DEM by Cook (
2007
), the LOLA DEM, and
theGLD100showninFig.
8.8
.
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