The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
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degree forward (GCD: 2.452 meter), 5 degree backward
(GCD:2.187 meter), 0.62 base-height ratio, could greatly
reduce the shading effect of high elevation difference
area and the backward image is suitable to produce ortho
image. The acquisition time difference of two cameras is
52 seconds, the short interval of acquisition time is
favorable for stereo observation and image matching.
And the effective swath of CARTOSAT-1 stereo pair is 26
kilometers due to earth rotation. The two independent
camera system of CARTOSAT-1 could work simultaneously
and enables the acquisition of continuous swath up to 4000
kilometers which is only restricted by the storage and downlink
capacity of the satellite. So, the characteristic of CARTOSAT-1
is designed for advanced and large scale mapping
applications.
IKONOS, QuickBird, Orb View, CARTOSAT-1, ALOS PRISM,
SPOT5 HRS, ASTER are main along-track stereo cartographic
applications satellites. And the resolution of IKONOS,
QuickBird, OrbView is from 0.6 meter to l.Ometer, the
resolution of CARTOSAT-1 and ALOS PRISM is 2.3meter, the
resolution of SPOT5 HRS, ASTER is 10 to 15 meter. Compared
with popular IKONOS and SPOT5 stereo data, CARTOSAT-1
stereo data has advantage in large-scale data acquisition and
disadvantage in low geometric accuracy without ground control
points and lacking multi-spectral data. And lacking
internationally application cases of India remote sensing data
blocks the marketing of IRS satellite data.
There are many researches(Space Imaging 2002;, DigitalGlobe
2006; ORBIMAGE 2004; Fraser 2001; Fraser 2003; Li 2000;
Tao 2000; Tao 2001; Jacek 2003; Toutin 2003 ) about the
surveying and mapping application of IKONOS, QuickBird,
OrbView, SPOT5 HRS and ASTER, but very few about
CARTOSAT-1. In this paper, we tested a pair of CARTOSAT-
1 stereo pair of Beijing area and the results show that the
planimetry and height accuracy of CARTOSAT-1 stereo pair is
70 meter without Ground Control Points(GCPs), and could
reach 5-meter with high-accurate GCPs which meets the
national 1:50,000 topographic maps survey specifications
specifications
CARTOSAT-
1
IKONOS
SPOT5
HRS
GSD(meter)
2.5X2.5
1.0X1.0
10.0X5.0
base-height ratio
0.62
0.54-0.87
0.82
Orbit Height(km)
618
680
832
Quantization
10
11
8
Data quality
good
excellent
fair
Multi spectral data
No
Yes
No*
Accuracy without
ground
control(meter)
<80
<20
<50
Accuracy with
ground
control(meter)
5
1
10
Orbit orient
accuracy
fair
good
good
Data acquisition
capability (small
area)
good
good
good
Data acquisition
capability (large
area)
good
fair
good
standard scene
(square km)
30*30
11*11
120*60
standard stereo
pair (square km)
About 26*26
About
11*11
About
120*60
Continuous swath
length(km)
>4000
<600
Notes: * SPOT5 HRS is panchromatic and HRG has multi-spectral data
which is a different system from HRS from camera specification and
control system.
Table 1. Comparison of along-track stereo mapping satellites
2. CARTOSAT-1 ORIENTATION PRINCIPLE AND
METHODS
Like IKONOS, QuickBird and OrbView, CARTOSAT-1
provides Rational Polynomial Coefficients(RPC) of Rational
Function Model (RFM) for each scene, and it also provides
rigor imaging parameters in LGSOWG format. And RFM is
more popular in photogrametric processing.
2.1 RFM definition
RFM is the initial of Rational Function Model,RFM is a
common geometric model of the satellite imaging which
mapping 3-dimension ground point to 2-dimension image
point.( Tao 2000; Tao 2001; OGC 1999; Hartley 1997)
Num r (X.,Y„Z.)
Den r (X n ,Y n ,Z„)
Num c {X m ,Y„Z.)
Den c (X„,Y n ,Z„)
Where, X n , Y n and Z n are regularized 3-dimensional space
coordinate, and P n and C n is corresponding regularized image
coordinate:
X.
Y.
z-z 0
z s
(2)
(3)
Where (X,Y,Z) , (X 0 ,Y 0 ,Z 0 ) and (X S ,7 S ,Z 5 )
are the 3-dimensional coordinate, offset and scaling
coefficients independently; and (v,c) , (v ,C a ) and
(v s ,C s ) are the 2-dimensional coordinate, offset and
scaling coefficients independently;