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
POLINSAR EXPERIMENTS
OF MULTI-MODE X-BAND DATA OVER SOUTH AREA OF CHINA
Lijun Lu, Qin Yan, MinyanDuan, Yanmei Zhang
Chinese Academy of Surveying and Mapping, Lianhuachi west road, No 28,100830,Beijing, P.R.China
lulijun2002@gmail.com
Commission VII, VII /7
KEY WORDS: PolInSAR, land classification, objects detection, DSM mapping
ABSTRACT:
This paper makes the polarimetric and polarimetric interferometric synthetic aperture radar (PolInSAR) experiments with the high-
resolution X-band data acquired by Multi-mode airborne SAR system over an area around Linshui, south of China containing tropic
vegetation and urban areas. Polarimetric analysis for typical tropic vegetations and man-made objects are presented, some
polarimetric descriptors sensitive to vegetations and man-made objects are selected. Then, the PolInSAR information contained in
the data is investigated, considering characteristics of the Multi-mode-XSAR dataset, a dual-baseline polarimetric interferometry
method is proposed in this paper. The method both guarantees the high coherence on fully polarimetric data and combines the
benefits of short and long baseline that helpful to the phase unwrapping and height sensitivity promotion. PolInSAR experiment
results displayed demonstrates Multi-mode-XSAR datasets have intuitive capabilities for amount of application of land classification,
objects detection and DSM mapping.
1. INTRODUCTION
Nowadays, Polarimetric and Interferometric Synthetic Aperture
Radar (PolInSAR), as good combination the advantages of SAR
Interferometry and SAR Polarimetry, has been widely applied
to classification of crops and forests, man-made target detection,
measurement of soil, quantitative tree height determination,
ground topography mapping and etc. Different from the
previous airborne PolInSAR system, Multi-mode-XSAR system
developed by the China Electronics Technology Group
Corporation 38 department (CET38) provide the possibility to
simultaneously observe the ground surface more than once by
altering transmitting and receiving mode of pulse signal.
Therefore, it is essential to start exploring the potential of multi-
mode-XSAR datasets for objects interpretation and digital
surface model (DSM) mapping.
Section 2 is dedicated to the presentation of multi-mode-XSAR,
the experimental airborne SAR system developed by CET38.
And the multi-mode-XSAR dataset and the corresponding
ground measurements are described. In Section 3 describes a
polarimetric analysis for typical vegetations and man-made
objects, some polarimetric descriptors sensitive to vegetations
and man-made objects are selected for land classification and
objects detection.
Then, section 4 concerns the phase information in the datasets.
Considering characteristics of the multi-mode-XSAR dataset, a
dual-baseline polarimetric interferometry method is proposed in
this paper. On one hand, it guarantees the high coherence on
fully polarimetric data; on the other hand, it combines the
benefits of short and long baseline that helpful to the phase
unwrapping and height sensitivity promotion.
Next, section 5 of this paper displays the PolInSAR experiment
results of the land classification, man-made objects detection
and DSM mapping. Finally, section 6 gives the conclusion of
polInSAR experiment with multi-mode-XSAR data.
2. MULTI-MODE-XSARSYSTEM AND DATASETS
2.1 Multi-mode-XSAR System
Multi-mode-XSAR system is developed by CET38. The radar
system is placed on China “Y-7” airborne platform and the
mean flight velocity is nearly 120 m/sec, at 5000m altitude. The
radar incidence angle could be adjusted from 37 degree to 45
degree and the resolutions are 0.1m, 0.4m (azimuth resolution
and slant resolution). Especially, it can provide three kinds of
working modes including bistatic, ping-pang and mixed modes.
The bistatic mode represents one antenna transmit signal and
two antennas synchronously receive signals; the ping-pang
mode represents antenna pairs alternately transmit and receive
signal via the way of transferring transmit/receive(T/R)switch;
the mixed mode represents the bistatic mode and the ping-pang
mode alternately works at the cost of reducing system
bandwidth. The table 1 gives the detailed configuration
parameters of Multi-mode-XSAR system.
Table 1.Parameters of Multi-mode-XSAR system.
Mode Bandwidth Polar Swath width
[MHz] (km)
bistatic 360 Full 2
ping-pang 300 Full 2
mixed 250 Full 1
2.2 Dataset and ground measurement
CET 38 performed several flight plans in LingShui of the south
of China from 2009 to 2010, acquiring about 2000 km”
PolInSAR datasets over LingShui area. At the same time,
three trihedral and dihedral corner reflectors were deployed on
the scene for polarimetric and geometric calibration. The three
trihedral corner reflectors mostly centralized on the airfield were
employed for polarimetric calibration, and i.e. are used to
accurately register the different polarization images and to
compute the differential delays between channels. The other
three trihedral and dihedral corner reflectors widely spread all
places are employed for geometric calibration, and i.e. are used
to accurately correct geometric position.
