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SITE SELECTION FOR SATELLITE GEOMETRIC TEST RANGE IN CHINA 
Xinxin Zhu a ’, Guo Zhang b , Qing Zhu c , Xinming Tang d 
a State key laboratory of Information Engineering in Surveying ,Mapping and Remote Sensing, Wuhan University, 
Wuhan, China, 430079, xxzhu20@163.com 
b State key laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, 
Wuhan, China, 430079, guozhang@whu.edu.cn 
c State key laboratory of Information Engineering in Surveying ,Mapping and Remote Sensing, Wuhan University, 
Wuhan, China, 430079, zhuqing@lmars.whu.edu.cn 
d Key Laboratory of Geo-informatics of State Bureau of Surveying and Mapping, Chinese Academy of Surveying and Mapping, 
16Beitaiping Road,Beijing, China, 100039, tang@casm.ac.cn 
KEY WORDS: geometric test range, calibration, free cloud, flat area, vertical displacement 
ABSTRACT: 
The high resolution satellite such as IKONOS, SPOT5 have built many geometric test ranges around the world for in-flight 
calibration to obtain high horizontal and vertical accuracy. This is one reason that their products are widely used in many fields. 
For a satellite geometric test range, how to select one is a critical problem. This paper focuses on the weather and terrain conditions 
while choosing a satellite geometric test range in China. 
In this paper, the weather condition is analyzed first. A free cloud area is likely to be chosen, and several areas will meet the 
condition. Then do terrain analysis for those areas which content weather condition, and select flat area because it can calibrate 
satellite parameters as well as mountain area and flat area is more convenient for arranging GCP (Ground Control Point). Area and 
cost conditions haven’t been detailed because authors take them as subjective factors. Last, an experiment is performed to show the 
process of test range selection. This experiment may give some suggestions about how to select a test range. 
1. INTRODUCTION 
With the development of remote sensing technology, satellite 
images are widely used in many areas. Some satellite images 
not only have high spatial resolution, but also have high 
location accuracy, such as IKONOS, SPOT5, and ects. As we 
know, during the emission of satellite, several factors causing 
the geometric parameters value which have been validated on 
the ground varied, launch shock; zero gravity. (D. Mulawa, 
2004) For the purpose of high location accuracy, ground 
calibration is needed to obtain a priori value for on-orbit use. 
Geometric test ranges are designed for this aim. SPOT series 
satellites, IKONOS, ALOS and so forth all have many test 
ranges around the world. By using geometric test ranges for 
calibrating, location accuracy can be improved prominently. 
During the first year of SPOT5’s running, its location accuracy 
being improved from 600 m rms to 20 m rms by means of 
ground geometric test ranges.(Bouillon and Gigord, 2004) 
(Bouillon et al., 2003) (Gachet, 2004) (Breton, E, 2002) This 
affirms geometric test ranges is a good method for geometric 
calibration. 
Satellite geometric calibration is one aspect hindering the avail 
of satellite image. And because no such test ranges has been in 
China now, in order to make good use of satellite images, it is 
essential to know how to select a test range first. 
2. ANALYSIS OF SELECTING A TEST RANGE 
To select a satellite test range generally consider four aspects as 
follows: 
• weather condition 
• terrain condition 
• area condition 
• cost condition 
Weather condition and terrain condition are mainly to be 
considered. Since area condition is depend on the satellite’s 
swath width, and cost condition sometime is a subjective factor. 
So in this article the emphasis is analyzing the weather and 
terrain conditions. 
2.1 Weather condition 
Cloud is being analyzed in weather condition. Its influence is 
on image quality. As satellite remote sensing is different from 
aerial remote sensing which can choose when to fly on the test 
range, satellites are running like clockwork in the space. The 
time pass by the test ranges can not be changed after emission. 
On purpose to obtain operative images when imaging on the 
test ranges, free cloud weather is needed. So a place having 
high probability of free cloud is like to be chosen (Gene Dial, 
2003) 
2.2 Terrain condition 
In spatial remote sensing calibration, a site having superior 
height variance is accepted for test range to eliminate the 
influence caused by height to improve horizontal accuracy. But 
space remote sensing is different. As the orbits of satellite are 
far away from the ground, satellite imaging is similar to parallel 
projection. The influence for horizontal accuracy due to great 
hypsography does not appear evidently, and for vertical 
accuracy, a good DEM can be used to improve it.