A geometric preprocessing model for airborne SAR image

2006 ◽  
Author(s):  
Dan Lu ◽  
Guoman Huang ◽  
Zheng Zhao
Keyword(s):  
Sar Image ◽  
Airborne Sar

scholarly journals Modifications of Range-Doppler Algorithm for Compensation of SAR Platform Motion Instabilities

2014 ◽  
Vol 60 (3) ◽  
pp. 225-231 ◽  
Author(s):  
Ievgen M. Gorovyi ◽  
Oleksandr O. Bezvesilniy ◽  
Dmytro M. Vavriv
Keyword(s):  
Experimental Data ◽  
Image Formation ◽  
Sar Image ◽  
Quadratic Map ◽  
Platform Motion ◽  
Airborne Sar ◽  
Short Time ◽  
Time Acquisition

Abstract Two modifications of the range-Doppler algorithm (RDA) have been proposed to solve problems of SAR platform motion instabilities. First, the multi-look processing based on the RDA with an extended Doppler bandwidth has been introduced for correction of radiometric errors. Second, the RDA has been modified to perform SAR image formation on short-time acquisition intervals to use it in a recently-developed local-quadratic map-drift autofocus (LQMDA) method. The performance of the methods is illustrated with experimental data obtained by airborne SAR systems.

scholarly journals Similarity measures of full polarimetric SAR images fusion for improved SAR image matching

2015 ◽  
Vol XL-7/W4 ◽  
pp. 13-16 ◽  
Author(s):  
H. Ding
Keyword(s):  
Similarity Measure ◽  
Image Matching ◽  
Stereo Matching ◽  
Similarity Measures ◽  
Sar Image ◽  
Polarimetric Sar ◽  
Sar Images ◽  
Sar Data ◽  
Sar Imagery ◽  
Airborne Sar

China’s first airborne SAR mapping system (CASMSAR) developed by Chinese Academy of Surveying and Mapping can acquire high-resolution and full polarimetric (HH, HV, VH and VV) Synthetic aperture radar (SAR) data. It has the ability to acquire X-band full polarimetric SAR data at a resolution of 0.5m. However, the existence of speckles which is inherent in SAR imagery affects visual interpretation and image processing badly, and challenges the assumption that conjugate points appear similar to each other in matching processing. In addition, researches show that speckles are multiplicative speckles, and most similarity measures of SAR image matching are sensitive to them. Thus, matching outcomes of SAR images acquired by most similarity measures are not reliable and with bad accuracy. Meanwhile, every polarimetric SAR image has different backscattering information of objects from each other and four polarimetric SAR data contain most basic and a large amount of redundancy information to improve matching. Therefore, we introduced logarithmically transformation and a stereo matching similarity measure into airborne full polarimetric SAR imagery. Firstly, in order to transform the multiplicative speckles into additivity ones and weaken speckles' influence on similarity measure, logarithmically transformation have to be taken to all images. Secondly, to prevent performance degradation of similarity measure caused by speckles, measure must be free or insensitive of additivity speckles. Thus, we introduced a stereo matching similarity measure, called Normalized Cross-Correlation (NCC), into full polarimetric SAR image matching. Thirdly, to take advantage of multi-polarimetric data and preserve the best similarity measure value, four measure values calculated between left and right single polarimetric SAR images are fused as final measure value for matching. The method was tested for matching under CASMSAR data. The results showed that the method delivered an effective performance on experimental imagery and can be used for airborne SAR matching applications.

scholarly journals Indoor Experiments of Bistatic/Multistatic GB-SAR with One-Stationary and One-Moving Antennae

2021 ◽  
Vol 13 (18) ◽  
pp. 3733
Author(s):  
Hoonyol Lee ◽  
Jihyun Moon
Keyword(s):  
Time Domain ◽  
Speckle Noise ◽  
The Other ◽  
Synthetic Aperture ◽  
Sar Image ◽  
Sar Images ◽  
Airborne Sar ◽  
Transmitting Antenna ◽  
Azimuth Resolution ◽  
Ku Band

Ground-based synthetic aperture radar (GB-SAR) is a useful tool to simulate advanced SAR systems with its flexibility on RF system and SAR configuration. This paper reports an indoor experiment of bistatic/multistatic GB-SAR operated in Ku-band with two antennae: one antenna was stationary on the ground and the other was moving along a linear rail. Multiple bistatic GB-SAR images were taken with various stationary antenna positions, and then averaged to simulate a multistatic GB-SAR configuration composed of a moving Tx antenna along a rail and multiple stationary Rx antennae with various viewing angles. This configuration simulates the use of a spaceborne/airborne SAR system as a transmitting antenna and multiple ground-based stationary antennae as receiving antennae to obtain omni-directional scattering images. This SAR geometry with one-stationary and one-moving antennae configuration was analyzed and a time-domain SAR focusing algorithm was adjusted to this geometry. Being stationary for one antenna, the Doppler rate was analyzed to be half of the monostatic case, and the azimuth resolution was doubled. Image quality was enhanced by identifying and reducing azimuth ambiguity. By averaging multiple bistatic images from various stationary antenna positions, a multistatic GB-SAR image was achieved to have better image swath and reduced speckle noise.

An Efficient Segmentation Method for Mariculture Areas on Airborne SAR Images

2019 ◽  
Vol 53 (3) ◽  
pp. 30-38
Author(s):  
Houjun Wang ◽  
Hui Liu ◽  
Ning Ding ◽  
Pingping Jing ◽  
Guangyu Li
Keyword(s):  
Image Data ◽  
Synthetic Aperture ◽  
Sar Image ◽  
Adaptive Segmentation ◽  
Segmentation Method ◽  
Clustering Method ◽  
Sar Images ◽  
Local Patch ◽  
Airborne Sar ◽  
Coarse To Fine

AbstractIn this paper, the problems of mariculture area segmentation and corresponding area value estimations are investigated on the basis of airborne synthetic aperture radar (SAR) images. In order to deal with a limited amount of noisy airborne SAR image data in an efficient way, an effective coarse-to-fine approach is proposed, consisting of three major components, including (1) an adaptive segmentation method for each local patch to remove noise from the ocean background, (2) a dynamic coarse-to-fine clustering method for grouping pixels to achieve image segments, and (3) a polygon-fitting-based algorithm to obtain regular borders for each region and corresponding area value. Some feasible experiments are operated based on the restricted airborne SAR images, and the effectiveness of the proposed algorithm is validated in terms of the provided pixel level evaluation annotations.

scholarly journals Refocusing Moving Ship Targets in SAR Images Based on Fast Minimum Entropy Phase Compensation

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1154 ◽  
Author(s):  
Xiangli Huang ◽  
Kefeng Ji ◽  
Xiangguang Leng ◽  
Ganggang Dong ◽  
Xiangwei Xing
Keyword(s):  
Synthetic Aperture Radar ◽  
Phase Error ◽  
Synthetic Aperture ◽  
Sar Image ◽  
Minimum Entropy ◽  
Sar Images ◽  
Phase Compensation ◽  
Translation Motion ◽  
Airborne Sar ◽  
Aperture Radar

Moving ship targets appear blurred and defocused in synthetic aperture radar (SAR) images due to the translation motion during the coherent processing. Motion compensation is required for refocusing moving ship targets in SAR scenes. A novel refocusing method for moving ship is developed in this paper. The method is exploiting inverse synthetic aperture radar (ISAR) technique to refocus the ship target in SAR image. Generally, most cases of refocusing are for raw echo data, not for SAR image. Taking into account the advantages of processing in SAR image, the processing data are SAR image rather than raw echo data in this paper. The ISAR processing is based on fast minimum entropy phase compensation method, an iterative approach to obtain the phase error. The proposed method has been tested using Spaceborne TerraSAR-X, Gaofeng-3 images and airborne SAR images of maritime targets.

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