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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