International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
4.3 Xilinhaote Project
Very recently CASM won the Xilinhaote project of about
100,000 qkm in the Inner Mongolia from the State Bureau of
Surveying and Mapping of China for this summer, dedicated to
use of the DGPS/IMU technology. It is 255 km from West to East
and 580 km from North to South in this aera. There are two parts
in this project, one of the 1:32,000 photo scale, the other is
1:50,000 photo scale. Now the mission is progressing steadily.
Table 4 shows the major project parameters.
Part I Part II
Area 35360qkm 65180gkm
Photo scale 1:32,000 1:50,000
Map scale 1:10,000 1:50,000
Blocks A B C D E
Ne. of flight? lias 32 78 15 15
lines
No. of total | 04] 1192 liés | eo «| sis
hotos
Table4. Major parameters of the Xilinhaote project.
5. EXPERIENCES
In the following, we will just mention some major Chinese
specialties for running DGPS/IMU-based photogrammetric
projects we learned through these projects.
5.1 Hardware Montage
In China aircraft for aerial photography belongs to a third party,
in general. In most cases, the contractor party of conducting a
mission of aerial photography rents an aircraft, mounts its aerial
camera or other necessary hardware in it, and removes all the
equipment after the mission. This makes the montage of GPS
antenna on top of an aircraft quite problematic.
5.2 Coordinate Systems
Since there are very rigorous restrictions to deal with
transformations between global and local coordinate systems in
China, transformation parameters between the WGS84 coordinate
system and any local Chinese one are hardly to get directly.
Therefore, software requiring those transformation parameters has
either to make the interface open or to provide tools to generate
those parameters based on conjugate points.
5.3 System Calibration
To signalize GCPs in the calibration field can hardly be accepted
by practitioners in China. Nature object points have to be chosen.
There are some good AT software packages made in China which
may be adapted for the calibration. GeoLord-AT we used this
time is a good example. Now we are able to use an adapted
version to work on our project.
874
5.4 Administrative Restrictions
Because there are quite a few administrative restrictions with
respect to e.g. flight permission, aircraft montage (e.g. GPS
antenna) and map information or data access as well as use. Since
all institutions or companies conducting aerial photography in
China are still state-owned, it would hardly be expected not to
have any bureaucracy during procedures. Flight permission, for
instance, has to be applied for quite a time before the real flight
and the flight height once permitted is hardly to change later. All
these factors have to be taken into account for a successful
mission anyway.
6. CONCLUSIONS
The new DGPS/IMU technology for topographic mapping has
adopted in China. Our findings thereof could confirm again that:
® Direct georeferencing would be suitable for direct
orthophoto generation even of large scales;
€ Integrated sensor orientation using a limited number of
ground control points can compensate systematic errors and
makes the best way to replace the conventional aerial
triangulation;
€ For small scale mapping direct georeferencing should be
good enough to meet the accuracy requirements.
According to the latest information, there are three company has
imported (or in progress)DGPS/IMU system for mapping
applications expect CASM. Using digital aerial camera and
airborne laser scanner (LIDAR) mounted on a unique platform
supported by DGPS/IMU technology and making use of the
global DGPS networks it is to be expected in the near future that
spatial information would be deliverable within 24 hours from its
acquisition (Tang, 2004). We could expect that DGPS/IMU-based
photogrammetry would be going to dominate the topographic
mapping in China soon.
References:
Cramer, M., 2002: Experiences on operational GPS/inertial
system calibration in airborne photogrammetry. Journal GIS -
Geoinformationssysteme 14 (6), June 2002, Wichmann Verlag,
Heidelberg, Germany, pp. 37-42.
Grimm, A., 2003: 25 Jahre IGI, die Entwicklung von CCNS und
AEROcontrol. Photogrammetrie,
Fernerkundung, Geoinformation (PFG), 4/2003, pp. 245-258.
Kremer, J, 2002: CCNS/AEROcontrol - an Integrated
GPS/Inertial System for Direct Georeferencing of Airborne Image
Data. Symposium Gyro Technology 2002, Stuttgart, Germany, pp.
16.0 -16.9.
Tang. . L. 1999: Bemerkungen zur — automatischen
Aerotriangulation. Festschrift für Prof. Dr.-Ing. Heinrich Ebner
zum 60. Geburtstag, (Eds. Heipke/Mayer) Technische
Universität München, pp. 321-323.
Tang, L., Li, Y., Li, X., Zhao, J, Gong, X., 2003: Firs
Experiences with CCNS/AEROcontrol inChina. Photogrammetrie,
Fernerkundung, Geoinformation (PFG), 4/2003, pp. 335-344.
Tang, L., 2004: Spatial information from acquisition to delivery
within 24 hours: A dream or a reality? Accepted for Proceedings
of the 4th International Symposium on Mobile Mapping
Technology, Kunming, China, March 29-31, 2004.
KE
AE
Or
det
phe
ge
“tr
teri
pal
prc
col
ort
teri
car
rel
acc
Th
dis
rel
ha
im:
nat
an
inf
the
top
wil
rel
ort
ye
19
stu
aut
inf
pre
ort
to
ori
of
me
acc
acc
Col
prc
ort
fro
buf
col
ma
