Applications to Lunar Remote Sensing - 3D Computer Vision: Efficient Methods and Applications - page 333

The illumination angles of the LROC WAC global mosaic and most M 3 images
are too steep to clearly reveal low mare domes (cf. Fig. 8.20 ). However, the high-
land domes are well visible in these images. Hence, Herbort et al. ( 2011 )relyon
M 3 data for shape from shading based DEM construction (cf. Sect. 5.5 )astheM 3
data set provides radiance images, allowing one to apply the Hapke model (Hapke,
1981 , 1984 , 1986 ) to the resulting absolute physical reflectance values, along with
the pixel-wise illumination, viewing, and phase angles. DEMs of lunar highland
domes recently obtained with the method of Herbort et al. ( 2011 ) are presented in
Sect. 8.4.3.1 .
8.4.2.2 Telescopic CCD Imagery
Due to the lack of photometrically calibrated spacecraft imagery acquired under
strongly oblique illumination, Wöhler et al. ( 2006b ) utilise telescopic CCD im-
ages for the determination of the morphometric properties of lunar domes. To ac-
quire images of lunar domes, telescopes with apertures between 200 and 400 mm
were utilised in combination with digital CCD video cameras of different types
(Atik, ToUCam, Lumenera), relying on the acquisition technique described in
Sect. 8.2.2 .
The images shown in Figs. 8.21 b and 8.22 c were taken in the Johnson I band, a
bandpass filter transmitting near-infrared wavelengths between 700 and 1100 nm,
while the other telescopic images were acquired in integral visible light through
a UV+IR block filter which transmits wavelengths between 400 and 700 nm. The
telescopic CCD images in Figs. 8.21 - 8.25 are not geometrically rectified, which im-
plies a non-uniform direction-dependent pixel scale. The scale bars in these figures
therefore indicate the average pixel scale for each image. Labels without brackets
denote that a three-dimensional reconstruction of the corresponding dome has been
performed based on the respective image data, while labels in brackets are merely
shown for comparison. For our set of lunar domes, the image sections used for
three-dimensional reconstruction were extracted from the telescopic CCD images
rectified to perpendicular view. A correction of the gamma value of the camera has
been performed as described in Sect. 8.2.2 .
Figure 8.21 shows the dome fields near Arago in western Mare Tranquillitatis
and around Cauchy in central Mare Tranquillitatis as well as the dome chain at
the northern border of Mare Tranquillitatis termed 'Northern Tranquillitatis Align-
ment' (NTA) by Wöhler et al. ( 2007b ). The dome fields situated in Mare In-
sularum near the craters Hortensius, Milichius, and Tobias Mayer are shown in
Fig. 8.22 , while Fig. 8.23 displays the dome field in Mare Undarum (Lena et al.,
2008 ) and the large volcanic complex Mons Rümker in northern Oceanus Pro-
cellarum (Wöhler et al., 2007a ). For comparison, several isolated domes situated
outside the large dome fields are shown in Fig. 8.24 , while Fig. 8.25 shows a
dome at the southern rim of the crater Petavius which is associated with a pyro-
clastic deposit composed of dark material distributed across the surface by a vio-
lent volcanic eruption. This pyroclastic deposit is also mentioned by Gaddis et al.
( 2000 ).