교육용 인공위성 영상레이더 자료처리 공개 프로그램 (eSAR Processor) 의 개발

Development of an educational Synthetic Aperture Radar Processor

강원대학교 지구물리학과이 훈 열

hoonyol@kangwon.ac.kr

One Page Introduction to SAR• Active Imaging Radar• Microwave• Weather-free and Day & night im

aging• High Gain Antenna• Synthesized large aperture throug

h signal processing -> dramatically enhanced (azimuth) resolution

• 2D image + Phase = 3D measurement

• InSAR, DInSAR, PolSAR, Pol-InSAR, PSInSAR

• Detection, classification, mm-scale surface motion, etc.

SAR Product Levels

Product Levels Data Type Prospectus Users

0 RAW Geophysicist

1 Focused Scientist

2 Geocoded GIS specialist

3+ Fully calibrated GIS users

Geophysical Approach to SAR

Geophysicists are in a good position to

• understand SAR system through profound data processing from the beginning (RAW),

• read engineer’s mind who designed the system,

• do science,

• and give feedback to RF engineers.

SAR Processors

Commercial Educational

PriceExtremely expensive

Free

Learning Quick Slow

Use Convenient Difficult

Source Code Hidden Open

VersatilityLimited or even

dead endedOpen

Market limited Open to all

eSAR Processor• SAR Focusing and InSAR Processor• Developed for graduate course• Range-Doppler Algorithm• Effective use of computer facilities

– One PC for each student– Minimum PC specification (CPU, Memory, HDD)– Small areas

• Based on cygwin (Linux emulator for Windows, Free)• GNU C-Compiler (Free)• Machine independent FFT Algorithm from Numerical Recipes• Interactive education – can see each processing step• Open and easy source code (ANSI-C)• Everything’s Free• Open Forum• No GUI currently, but some can be added• Student study the SAR system and structure of data -> versatile to any data type

SAR FocusingFor MxN pixel image (2ax2b):

• Memory Usage= MxNx2(complex)x8(double) Bytes(ex. 64MB for 1024x4096, 256MB for 8192x2048)

• CPU Time= 2D FFT and iFFT= 2*Ma/2*N + 2*Nb/2*M= MN(a+b) multiplications(ex. 88M multiplications for 1024x4096. a few minutes in PIII CPU and dozens of seconds in PIV CPU )

• HDD– Minimum 4-look amplitude: MxN

(ex. 4M for 1024x4096)– Maximum: MxNx4(float)x2(complex)x

8(outputs)(ex. 256M for 1024x4096)

SAR Focusing Steps (2048x4096)

RAW Range Compressed Range Migrated

range

azi

mu

thazim

uth

fre

qu

ency

SAR Focusing Results

4-look SAR amplitude (40km x 20km)

More to come

• SAR Interferometry• SAR Polarimetry • Some GUI • More accurate and robust SAR focusing algorithm

• Open source code: www.kangwon.ac.kr/~geophy/

• An online (or offline) forum can be organized upon the user’s request.