|! XXXIX-B4, 2012
on of NAC DEMs can
aft orbit and camera
ges, the spacecraft is
ight line. In some cases
0 acquire stereo images
gle is the magnitude of
reo pairs. SOCET SET
stereo mates upon
or gives an estimate of
> 90% confidence level
ntal linear error in the
tion of the DEM. The
from nominal phase
can be as large as 2.0
oning phase and frozen
ision of as much as 3.0
by LOLA provide
pacecraft and the lunar
r, uncertainties in the
ffsets (£15m) between
ROC team is currently
ly register alimetric
et al. 2012). Using a
hm, the new automatic
'osition and pointing
images are acquired as
nts of the same region.
* LOLA
* NACDEM
4445 44.46
s)
ogram identifying the
| partition of the final
accuracy of the DEM
' the LOLA profiles.
the DEM to only one
ocedure ensures that the
ion. Other profiles that
ot be consistent from
to small unknowns 1n
tively flat are used as
raining portion of the
for artificial tilts in the
International Archives of the Photogrammetry, Remote Sensin
g and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
stereo model. If the remaining LOLA profiles have a spatial and
elevation offset from the initial LOLA profile, then the error in
the slope of the DEM could be up to 1? in the cross track
direction. Errors in the LOLA tracks can propagate over larger
distances away from the initial LOLA track. If the cross-track
distance is large (3 or more stereo pairs), the DEM can be
registered to another LOLA track without interfering with the
residual error in the bundle adjustment. Elevation controls are
then placed between the co-registered LOLA tracks.
S. APPLICATIONS
The NAC DEMs are the highest resolution topographic resource
of the lunar surface, and serve as a valuable tool to both the
scientific and space exploration communities. One of the
principal uses of the NAC DEMs is to place constraints on the
small-scale geomorphological characteristics of key science
sites. Constraints can be placed on the composition of surface
features by investigating different parameters of the DEM.
Studies by Jolliff et al. (2011) used NAC DEMS to characterize
locally elevated topographical features in the Compton-
Belkovich Th-anomaly. These volcanic domes were not
resolvable in other lunar topographical products and helped in
understanding the recent geological history of the Moon. Ashley
etal. (2011) used NAC topography to identify several areas of
negative and positive relief in the Al-Tusi melt deposit
associated with the King Crater impact event. DEMs can also be
useful for volume estimations. Mahanti et al. (2012) used a
DEM mosaic of ponded material in the lunar highland region to
calculate the amount of melt that had been emplaced in the
floors of craters in the area. Volumes of the ponded material
were measured by creating a polynomial mesh of the crater
from the DEM and then removing the relatively flat ponded
erater floor. Algorithms were then used to recover the DEMs
without the filled pond, and this estimate was then employed to
calculate the volume of the melt.
Site selection is critical to the success of any future lunar
mission. NAC DEMs will be crucial in manned or robotic
attempt to land on the surface. Increased hazard avoidance
capabilities in future missions will be able to pick landing sites
with a greater emphasis on science return and less on
engineering safety criteria (Johnson et al. 2005). NAC DEMs
provide a reference for three-dimensional flight plans and
provide meaningful hazard avoidance by locating steep slopes,
rocks, cliffs, gullies and other landing hazards, which can be
avoided by computing the local slope and roughness. A densely
populated elevation model will aid on-board landing system that
can autonomously and accurately determine spacecraft velocity
and position relative to the landing site. DEMs draped with an
orthophoto enhance site selection decisions with perspective
views and 3-d flight simulations.
Small craters, boulders, and hills can block communication with
Earth for landed assists near the poles. Knowledge provided by
NAC DEMs of these small obstacles reduce mission risk.
Such DEMs are also needed for traverse planning. Unnecessary
movement across the surface wastes precious resources and
therefore it is crucial that traverses are optimized in advance to
follow a least work path.
6. PRODUCTION AND FUTURE WORK
The process of reducing NAC frames to DEMs has evolved to
an efficient pipeline procedure with rigorous quality control
checks. To date, ASU has processed 130 individual stereo pairs
covering 11 CxP sites as well as 53 regions of scientific interest
covering a total area of —20,000 km? (Table 1). The total
coverage of the lunar surface is only 0.06%. The team at UA
has processed approximately 40 stereo pairs, which include 5
CxP regions of interest. OSU has produced approximately 20
DEMs produced from NAC images. USGS has processed 20
DEM mosaics of CxP regions of interest that include multiple
stereo pairs for each mosaic. ASU DEMs and associated
products can be downloaded from http://wms.lroc.asu.edu/lroc/
dtm select. These DEMs are described in the following table.
Additional DEMs (from USGS and UA) are available from
http://Immp.nasa.gov.
# of Total
Site name RMS | Average | # of Stereo c Tes e Site name RMS | Average dd ed e
(Lat/Lon) Error Error Pairs FER (Lat/Lon) Error Error Pairs eer
Apollo 11 Luna 16 Landing Site
(I°N23°E) 1.73 1.14 1 114 (0"N56*E) 3.62 2.48 1 117
Apollo 12 Luna 20 Landing Site
(°S337°E) 2.06 1.96 1 13 (4°N57°E) 6.78 5.24 1 122
Apollo 14 Luna 23/24 Landing
(17°8334°E) 3.15 2.43 1 121 (13°N62°E) 4.53 3.54 1 137
A
os 14.49 5.65 1 122 Korolev (2°N196°E) 7.12 4.91 1 112
te 2.61 1.84 6 682 Mairan T (42°312°E) 4,35 2.91 2 205
Apollo 17 Mare Crisium
(20°N30°E) 5.03 3.67 6 686 (17°N59°E) 0.99 0.76 3 427
*Aristarchus I *Mare Ingenii
(25°N331°E) 5.94 3.67 4 437 (35°S164°E) 4.82 3.36 4 695
Atlas Crater *Marius Hills
. . 38
(47°N44°E) 3.47 3.20 6 715 (14°N304°E) 3.80 2.35 3 8
Bhabha Plains o 29 22.28 16.41 2 286
(55°N198°E) 2.34 1.79 1 157 Moore F (38°N182°E) . ;
Compton-
Belkovich Dome | 812 5.90 140 Ne Cr 3.00 2.98 2 1226
61°N100°E)
Eratosthenes Orientale Basin
; 1.81 2 279
(15°N349°E) 3.89 2.42 I 802 (12°N238°E) 2.45 8
455
