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Fig. 8.15
DEM of the northern part of the tectonic fault Rupes Recta based on two images ac-
quired at different illumination conditions (
μ
1
175
.
6
◦
) by first applying the ra-
tio-based intensity error term (
3.50
) with smoothness and shadow constraints (
3.20
)and(
5.10
),
then using the resulting surface profile and albedo map as an initialisation to the shape from shad-
ing scheme that involves integrability constraint (
3.25
). (
a
) Scene illuminated from the east (
left
image
) and from the west (
right image
). (
b
) Shadow image. (
c
) Ratio image. (
d
) Albedo map ob-
tained according to (
3.49
). (
e
) Reconstructed surface profile, shown as
shaded relief
to accentuate
subtle surface structures. Along with the actual surface features, the bending of the surface due to
the Moon's spherical shape is visible in the horizontal image direction
13
.
7
◦
,
μ
2
=
=
struction is performed based on two images taken at different solar elevation angles
μ
1
=
15
.
5
◦
but virtually identical solar azimuth angles, using error
term (
3.50
). The average pixel pixel grey value
5
.
0
◦
and
μ
2
=
I
(
1
)
of the first image is scaled such
uv
I
(
1
)
I
(
2
)
that
sin
μ
1
/
sin
μ
2
, which means that on the average, the surface sec-
tion is assumed to be flat. A large-scale surface slope of angle
δ
in the direction of in-
cident light might be imposed by setting
/
=
uv
uv
I
(
1
)
I
(
2
)
δ)
—
with an absolutely calibrated CCD sensor one might think of deriving such a large-
scale slope directly from the surface reconstruction procedure. The reconstructed
surface profile contains several low ridges with altitudes of roughly 50 m along
with the lunar dome Herodotus
ω
. The albedo map obtained according to (
3.49
)dis-
plays a gradient in surface brightness from the lower right to the upper left corner
along with several ray structures running radial to the crater Aristarchus.
Figure
8.15
shows the northern part of the lunar tectonic fault Rupes Recta. The
images shown in Fig.
8.15
a were acquired at solar elevation angles
μ
1
=
/
=
sin
(μ
1
+
δ)/
sin
(μ
2
−
uv
uv
13
.
7
◦
and
175
.
6
◦
, which means that the scene is illuminated from opposite directions.
The scene was reconstructed by first applying the ratio-based intensity error (
3.50
)
with smoothness and shadow constraints (
3.20
) and (
5.10
), then using the resulting
surface profile and albedo map obtained by (
3.49
) as an initialisation to the shape
from shading scheme that involves integrability constraint (
3.25
). A third image
μ
2
=
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