Research On The Radiometric Resolution Of The Ocean SAR

Spaceborne Synthetic Aperture Radar,which has been widely used in the field of remote sensing,is very sensitive to the microwave backscattering of rough sea surface,and it is able to observe the ocean continue continually regardless of the weather conditions.SAR can obtain images of meso-scale oceanic phenomenon,ship wakes,oil and sea ice.To a large extent,the quality of these images will determine the performance of many applications,such as parameters inversion and target recognition.Radiation resolution is the key to the improvement of image quality for the case of weak scattering ocean SAR images.High radiation resolution can abate the influence of noise,and thus reflect the difference of the targets and sea surface.In addition,the contrast signal intensity is an important factor affecting image quality.The greater the intensity of signal difference is,the more obvious the contrast of target signal and the surface of the background are,and the easier target will be detected.Therefore,both radiation resolution and contrast signal intensity should be considered in the research of the radiometric resolution of ocean SAR.In the process of image processing,attention should be paid to both the improvement of the radiation resolution and the decrease of the loss of the contrast signal intensity.This paper,which is based on the experimental analysis of meso-scale oceanic phenomenon,focuses on the radiation resolution system of ocean SAR and the method to improve radiation resolution.The main contents are as follows.(1)A brief introduction of the SAR imaging theory,including electromagnetic scattering model and the pattern of common meso-scale oceanic phenomenon in SAR images.And according to the oceanic SAR image analysis of sea clutter statistical properties,this paper introduces subsequent radiation resolution definition.(2)Based on the statistical feature of SAR image,combined with the influence of additive noise and coherent speckle,radiation resolution formula is derived.This paper established the radiation resolution system of ocean SAR,reviewed the delivery process,and introduced the concept of visibility function.(3)Based on the introduction of the traditional radiation resolution improved methods,this paper focuses on the BM3 D algorithm in the field of improving visibility function of the ocean SAR image.Aiming at the existing problem of algorithm,parameters selection strategy is put forward.The algorithm performance is improved,and the visibility function of the image is effectively improved.