V = Bg + Bt T L S P. Go
FEES B P
y = Et, P
Where, B,—[-fx.. Sys "fal is the unknown coefficient matrix
of ground point increment, Bi-[fao, fia. fuos fun: fio fifi Jin
Figo: fal” (;=1,2) is the unknown coefficient matrix of the
refined model parameters;
L is the constant vector, which L,,—-[0-xo, y-vo] is the residuals
for image coordinate observation value, L"[X-Xo, Y-Yo, ZZ
is the residuals for ground coordinate observation value;
x *, y! is the calculated image coordinate based on the initial
value of unknown parameters, [Y „ZT for the initial
approximation or adjustment iterative approximation value;
glAXAY.AZ]" and ta, ay, Py. by Co Cu So fis 80 81)”
represent the increment of ground control point coordinates,
refined ephemeris model parameters and refined attitude model
parameters;
P. Pg. Ptare the model parameters weight matrix of image
coordinates, the ground point coordinates, and ephemeris
model
calculated by corresponding accuracy of observation values.
attitude observation drift parameters, which are
The accuracy of refined parameters (sig. ig, Meg) consistent
with the accuracy of the satellite orbit surveying, (1,4, pi, Mot)
consistent with the accuracy of satellite speed, mg, my
consistent with the attitude measurement and control accuracy,
ma, m,, with the same accuracy to the attitude stability(change
rate).
The ground point coordinates and the parameters of refined
orbit attitude model could be solved by least squares.
3. TERRASAR STEREO POSITIONING TEST
3.1 Test data
Experiment with TerraSAR-X satellite images, TerraSAR is a
new commercial high-resolution radar satellite for earth
exploration, which manufacturing joint by the German Space
Agency and the European Astor company, moving in the sun
synchronous orbit with 514 km altitude and 98 degrees
inclination, and revisit cycle of 11 days. The sensor has a
spatial resolution down to 1 m and operates in Stripmap,
Spotlight, and ScanSAR modes with selectable or dual
polarization (Buckreuss , 2003, Schwerdt, 2005) .
Stereo positioning respectively adopt the same side-looking
direction stereo images and opposite side-looking direction
stereo images to test, the same side-looking direction stereo
positioning refer to the ground intersection point on one side of
two radar sensors site, while the opposite side looking direction
stereo positioning mean the ground intersection point between
the two sensors site. The length of same side-looking direction
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
stereo baseline or the forward intersection angle is usually
smaller than that of opposite direction.
TerraSAR-X same side-looking direction stereo images got in
October 2009, which located in the steepness Mountains in
western China, the elevation of the measured area is at 3500 m -
5500 m, and the geographical coordinate of center area is
(32.25°, 95.93°) the sample resolution in azimuth direction
respectively and in slant range direction respectively are
(2.18m,1.36m),(2.34m,1.36m).the two scenes are as shown in
Figure (3).
Figure 3. the same side-looking direction stereo images
The base-height ratio between two images is 0.078, the forward
intersection angle between the homologous and corresponding
ground points is about 12 degree, and the two image overlap
area greater than 80%, in this area totally have 22 known
coordinates ground points, the relationship between image and
the ground point distribution shown in Figure (4).
TerraSAR-X opposite side-looking direction stereo images got
in July 2009, the geographical coordinate of image center area
is (31.15, 94.32) . the sample resolution in azimuth direction
and in slant range direction for the two SAR images
respectively are (2.03m, 1.36m), (1.58m, 1.36m). The elevation
of surveying area is at 3800m -5600m, the base-height ratio is
1.27, and the forward intersection angle of ground point is 67
degree, images overlap area within the known geographical
coordinates points are total of 12, the relationship between the
two scene images and ground points distribution shown in
Figure (5) below.
Figd. the distribution of same Fig5. the distribution of opposite
side-looking direction stereo side-looking direction — stereo
images and ground points images and ground points
Ground known points available through triangulation
encryption methods by optical SPOTS HRS and HRG images
with Integration Mapping Software PixelGrid (Zhang. 2009),
and the precision higher than the accuracy of 1:50 000
topographic maps.
3.2 Test and Test analysis
(1) TerraSAR imaging compensated attitudes
