International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012 
XXII ISPRS Congress, 25 August - 01 September 2012, Melbourne, Australia 
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Figure 3. The registered Chang’E-l (a) and SELENE laser 
altimetry data (b) directly overlaid on the Chang’E-l images 
(backward images) at the Sinus Iridium area, respectively 
Figure 4. The 2D grey-scale images from Chang’E-l laser 
altimetry data (a) and SELENE laser altimetry data (b) with the 
same 360-m resolution 
The obtained transformation parameters were used to register 
the Chang’E-l laser altimeter data to the SELENE reference 
frame and remove the systematic shifts between them. After the 
least squares adjustment, the internal relative positions and 
orientations of the two DEMs remain the same. Table 1 shows 
the obtained transformation parameters between the Chang’E-l 
DEM and the SELENE DEM, which indicate the differences in 
the positional and orientation components between these two 
data sets. For the Sinus Iridium area, there is about 288 m offset 
between these two data sets in the horizontal direction, and the 
SELENE laser altimeter data is higher than the Chang’E-l laser 
altimeter data by about 550 m. The deviations in rotations 
between these two data sets are small. The scale factor is 
approximately 1. 
Name 
Values at 
Sinus Iridium 
Scale 
AX (longitude, degree) 
AT (latitude, degree) 
A Z (altitude) 
A (p (arc) 
A CO (arc) 
A K (arc) 
1.00746 
0.0290204 (880m) 
-0.0305055 (-925m) 
544.733 m 
0.0038 
-4.5158e-004 
0.0014 
Table 1. Transformation parameters between Chang’E-l and 
SELENE laser altimeter data at Sinus Iridium area 
To further examine the performances of the least squares 
adjustment, two tracks of the SELENE laser altimeter data were 
selected for detailed analyses at the Sinus Iridium area, as 
illustrated in Figure 3(b), which are much denser than the 
Chang’E-l laser altimetry data. For each track, two profiles 
were derived. The first profile was obtained by directly 
connecting the SELENE laser points on the track (red lines in 
Figure 5). The second profile was derived from the interpolated 
DEM generated from the Chang’E-l laser altimetry data (blue 
lines in Figure 5). These profiles can be used to examine the 
relative topography derived from the data sets from these two 
missions. 
Distance (Degree) 
Distance (Degree) 
(a) 
Distance (Degree) 
Profile from CE LA DEM after transfer 
Profile from SELENE LA data 
Distance (Degree) 
(b) 
| Track 2 | 
Figure 5. Profiles comparison between the SELENE and 
Chang’E-l data sets, (a) and (b): the profiles from track 1 
before and after transformation, respectively, (c) and (d): the 
profiles from track 2 before and after transformation, 
respectively 
From Figure 5, it can be noticed that the general trend among 
these profiles are identical to the real terrain of the Moon. 
Because the DEM are interpolated from the relatively sparse 
Chang’E-l laser altimeter points which may not be sufficient to 
represent the actual topography in the area. The profile derived 
from the DEM generated using the Chang’E-l laser altimetry 
data show relatively smooth topography compared with the 
other one. Statistical data including average, maximum, 
minimum and standard deviation values of the differences for 
each track and the whole area before and after the Least 
Squares Matching at Sinus Iridium area are listed in Table 2.