The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
Picture 5 the three-dimension and plane diagram of DEM errors
is the local radius of the ellipsoid, r 0 = DsO + Xs * Ji ■> DsO -
range, Xs - the resolution in range Ji -the coordinate in range.,
can be caculated , So
H 0 — ( r o"*"
cos(0 o + 0 O )
)cos(0 o +0 o )
the height information of corresponding target P, can be gotten ,
if it is taken in the expression of supposing the ground as the
flat. Where hj is the height relative to the plane of coordinate
axes X , it neglects the ellipsoidal influence between the two
objects. If ellipsoidal influence between P 0 and Pj is taken into
account, the true height of Pj is hj :
4. QUANTITATIVE ANALYSIS AND CORRECT OF
EARTH’S CURVATURE INFLUENCE IN
SPORNEBORNE INSAR HEIGHT SUEVEY
hi =
hj
cos(3
Re)
To Spomebome InSAR, because the satellite orbital altitude is
comparatively more higher , the distance between subsatellite
point and the mapping area is to hundreds of kilometers,
mapping area coverage is uauarlly a few of ten kilometers, so
the earth’s spheroid effect should be taken into account,
otherwise it will bring the height error. When considering the
earth’s spheroid influence, the parameters such as satellite
platform altitude must be corrected.
♦ y
Picture 6 geometry sketch diagram of height errors caused
from spheroid effect.
In picture 6, Suppose the center of the reference ellipsoid is
point O, the distance between M and PO is rO. In AMOP 0 , on
the basis of the law of cosines ,
cos# 0
(R e + \f + ( R e +H 0 ) 2 ~r 0 2
2(R e +6 0 )(R e +H 0 )
In the expression , ^ _ ^.i^Axcos^^ > Ax is the coordinate
R e
difference of two object in range .
Then we will quantitatively analyze and compare the height
measurement errors caused by without regard to the influence
of the earth’s curvature in spomebome InSAR height survey
with simulative data . Choose the baseline parameter of ERS-
1/2, when ***, B = 354.56m, h = 1570m (the mean ground
elevation of simulative data ) , Re = 6374732.39m ( the local
earth’s mean redius of curvature ) , on the assumption that the
ground range resolution is 15meter, the azimuth resolution is 4
meter, so when the area of height measurement is
60KM*60KM , the pixels in range and in azimuth are 4000 and
15000. Simulant DEM is as follows picture 7-a .
Picture 7 The comparison DEM obtained by taked the earth’s
surface as plane with simlaive DEM
The DEM obtained on the condition that the ground is plane
using the above-mentioned transformable expressions is
showed as picture 7-b. It is nearly no change to compare picture
7-a with picture 7-b . But in fact the two diagrams are different
from each other. In order to compare the error ,the two
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