A descalloping postprocessor for ScanSAR images of ocean scenes

Roland Romeiser, Jochen Horstmann, Michael J. Caruso, Hans C Graber

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Due to its specific way of recording signals from multiple adjacent swaths in an alternating manner, a scanning synthetic aperture radar (SAR) (ScanSAR) cannot sample Doppler histories continuously like a SAR in stripmap mode. This can cause an effect known as azimuth scalloping, a wavelike modulation of the image intensity in near-azimuth direction. In theory, azimuth scalloping can be straightened out by using appropriate beam pattern corrections and multilooking techniques in the SAR processor. This works well over land, but lower signal-to-noise ratios and less accurate Doppler centroid estimates over water cause significant residual scalloping in many ScanSAR images of ocean scenes. The scalloping patterns hamper a correct interpretation of signatures of wind streaks, waves, and other phenomena. To overcome this problem once and for all, we have developed an algorithm that can eliminate scalloping patterns from existing ScanSAR images by postprocessing. Our algorithm detects the dominant scalloping pattern in an image automatically and eliminates most of it with very small side effects. We treat the scalloping pattern as a multiplicative effect, i.e., the amplitude spectrum of an affected image is assumed to be the convolution of the amplitude spectra of the unscalloped image and of the scalloping pattern. The proposed descalloping technique works partly in the spatial and partly in the spectral domain to approximate an exact deconvolution. We give a detailed technical description, show example results, and perform a quality analysis. We demonstrate the positive effects of the proposed descalloping treatment with a wind field retrieval example.

Original languageEnglish (US)
Article number6377292
Pages (from-to)3259-3272
Number of pages14
JournalIEEE Transactions on Geoscience and Remote Sensing
Volume51
Issue number6
DOIs
StatePublished - 2013

Fingerprint

Synthetic aperture radar
synthetic aperture radar
Scanning
ocean
azimuth
Deconvolution
Convolution
Signal to noise ratio
wind wave
deconvolution
Modulation
wind field
signal-to-noise ratio
Water
history
effect

Keywords

  • Filtering
  • image processing
  • radar data processing
  • remote sensing
  • synthetic aperture radar (SAR)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Earth and Planetary Sciences(all)

Cite this

A descalloping postprocessor for ScanSAR images of ocean scenes. / Romeiser, Roland; Horstmann, Jochen; Caruso, Michael J.; Graber, Hans C.

In: IEEE Transactions on Geoscience and Remote Sensing, Vol. 51, No. 6, 6377292, 2013, p. 3259-3272.

Research output: Contribution to journalArticle

@article{24e6408c88ce42d6b43a25158ab2e4b0,
title = "A descalloping postprocessor for ScanSAR images of ocean scenes",
abstract = "Due to its specific way of recording signals from multiple adjacent swaths in an alternating manner, a scanning synthetic aperture radar (SAR) (ScanSAR) cannot sample Doppler histories continuously like a SAR in stripmap mode. This can cause an effect known as azimuth scalloping, a wavelike modulation of the image intensity in near-azimuth direction. In theory, azimuth scalloping can be straightened out by using appropriate beam pattern corrections and multilooking techniques in the SAR processor. This works well over land, but lower signal-to-noise ratios and less accurate Doppler centroid estimates over water cause significant residual scalloping in many ScanSAR images of ocean scenes. The scalloping patterns hamper a correct interpretation of signatures of wind streaks, waves, and other phenomena. To overcome this problem once and for all, we have developed an algorithm that can eliminate scalloping patterns from existing ScanSAR images by postprocessing. Our algorithm detects the dominant scalloping pattern in an image automatically and eliminates most of it with very small side effects. We treat the scalloping pattern as a multiplicative effect, i.e., the amplitude spectrum of an affected image is assumed to be the convolution of the amplitude spectra of the unscalloped image and of the scalloping pattern. The proposed descalloping technique works partly in the spatial and partly in the spectral domain to approximate an exact deconvolution. We give a detailed technical description, show example results, and perform a quality analysis. We demonstrate the positive effects of the proposed descalloping treatment with a wind field retrieval example.",
keywords = "Filtering, image processing, radar data processing, remote sensing, synthetic aperture radar (SAR)",
author = "Roland Romeiser and Jochen Horstmann and Caruso, {Michael J.} and Graber, {Hans C}",
year = "2013",
doi = "10.1109/TGRS.2012.2222648",
language = "English (US)",
volume = "51",
pages = "3259--3272",
journal = "IEEE Transactions on Geoscience and Remote Sensing",
issn = "0196-2892",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "6",

}

TY - JOUR

T1 - A descalloping postprocessor for ScanSAR images of ocean scenes

AU - Romeiser, Roland

AU - Horstmann, Jochen

AU - Caruso, Michael J.

AU - Graber, Hans C

PY - 2013

Y1 - 2013

N2 - Due to its specific way of recording signals from multiple adjacent swaths in an alternating manner, a scanning synthetic aperture radar (SAR) (ScanSAR) cannot sample Doppler histories continuously like a SAR in stripmap mode. This can cause an effect known as azimuth scalloping, a wavelike modulation of the image intensity in near-azimuth direction. In theory, azimuth scalloping can be straightened out by using appropriate beam pattern corrections and multilooking techniques in the SAR processor. This works well over land, but lower signal-to-noise ratios and less accurate Doppler centroid estimates over water cause significant residual scalloping in many ScanSAR images of ocean scenes. The scalloping patterns hamper a correct interpretation of signatures of wind streaks, waves, and other phenomena. To overcome this problem once and for all, we have developed an algorithm that can eliminate scalloping patterns from existing ScanSAR images by postprocessing. Our algorithm detects the dominant scalloping pattern in an image automatically and eliminates most of it with very small side effects. We treat the scalloping pattern as a multiplicative effect, i.e., the amplitude spectrum of an affected image is assumed to be the convolution of the amplitude spectra of the unscalloped image and of the scalloping pattern. The proposed descalloping technique works partly in the spatial and partly in the spectral domain to approximate an exact deconvolution. We give a detailed technical description, show example results, and perform a quality analysis. We demonstrate the positive effects of the proposed descalloping treatment with a wind field retrieval example.

AB - Due to its specific way of recording signals from multiple adjacent swaths in an alternating manner, a scanning synthetic aperture radar (SAR) (ScanSAR) cannot sample Doppler histories continuously like a SAR in stripmap mode. This can cause an effect known as azimuth scalloping, a wavelike modulation of the image intensity in near-azimuth direction. In theory, azimuth scalloping can be straightened out by using appropriate beam pattern corrections and multilooking techniques in the SAR processor. This works well over land, but lower signal-to-noise ratios and less accurate Doppler centroid estimates over water cause significant residual scalloping in many ScanSAR images of ocean scenes. The scalloping patterns hamper a correct interpretation of signatures of wind streaks, waves, and other phenomena. To overcome this problem once and for all, we have developed an algorithm that can eliminate scalloping patterns from existing ScanSAR images by postprocessing. Our algorithm detects the dominant scalloping pattern in an image automatically and eliminates most of it with very small side effects. We treat the scalloping pattern as a multiplicative effect, i.e., the amplitude spectrum of an affected image is assumed to be the convolution of the amplitude spectra of the unscalloped image and of the scalloping pattern. The proposed descalloping technique works partly in the spatial and partly in the spectral domain to approximate an exact deconvolution. We give a detailed technical description, show example results, and perform a quality analysis. We demonstrate the positive effects of the proposed descalloping treatment with a wind field retrieval example.

KW - Filtering

KW - image processing

KW - radar data processing

KW - remote sensing

KW - synthetic aperture radar (SAR)

UR - http://www.scopus.com/inward/record.url?scp=84878133367&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84878133367&partnerID=8YFLogxK

U2 - 10.1109/TGRS.2012.2222648

DO - 10.1109/TGRS.2012.2222648

M3 - Article

AN - SCOPUS:84878133367

VL - 51

SP - 3259

EP - 3272

JO - IEEE Transactions on Geoscience and Remote Sensing

JF - IEEE Transactions on Geoscience and Remote Sensing

SN - 0196-2892

IS - 6

M1 - 6377292

ER -