本文選題：合成孔徑雷達(dá) + 極坐標(biāo)格式算法　； 參考：《西安電子科技大學(xué)》2014年碩士論文

【摘要】：合成孔徑雷達(dá)(SAR)作為一種高分辨率成像雷達(dá),在當(dāng)代遙感成像領(lǐng)域發(fā)揮著重要的作用,是重要的成像工具之一。它能夠獲得高質(zhì)量,高分辨率的圖像,在國(guó)防事業(yè)和國(guó)民的日常生活中得到了廣泛的應(yīng)用。然而,隨著現(xiàn)代軍事武器的發(fā)展和人們對(duì)生活質(zhì)量要求的提高,SAR成像技術(shù)及圖像處理技術(shù)一直是學(xué)者們研究的熱點(diǎn)話題。迄今為止,雖然雷達(dá)成像技術(shù)領(lǐng)域已經(jīng)提出了很多有效的SAR成像及圖像處理方法,但在實(shí)際應(yīng)用中,由于成像目標(biāo)強(qiáng)度的多樣化和成像場(chǎng)景的復(fù)雜化,SAR成像技術(shù)及圖像處理技術(shù)仍然面臨著巨大的挑戰(zhàn)。本文針對(duì)場(chǎng)景中存在很多強(qiáng)目標(biāo)點(diǎn)的情況進(jìn)行了詳細(xì)的分析研究,主要研究成果如下:1.提出了一種基于旋轉(zhuǎn)坐標(biāo)系的極坐標(biāo)格式算法(MPFA)。該方法適用于大斜視情況,它是以極坐標(biāo)格式算法(PFA)為基礎(chǔ),將SAR成像的幾何坐標(biāo)系旋轉(zhuǎn)斜視角度,在旋轉(zhuǎn)坐標(biāo)系下重新計(jì)算合成孔徑雷達(dá)的坐標(biāo),然后獲取雷達(dá)與目標(biāo)點(diǎn)之間的距離。通過(guò)幾何坐標(biāo)系的旋轉(zhuǎn),將斜視情況下的幾何模型轉(zhuǎn)化到了正側(cè)視情況下的模型,該方法的提出不但克服了PFA只適用于正側(cè)視的缺陷,而且使成像目標(biāo)在大斜視情況下仍為正十字狀,為后續(xù)的SAR圖像旁瓣抑制工作奠定了便利基礎(chǔ)。2.提出了一種基于模值約束的空間變跡法(CMoSVA)。該方法是基于經(jīng)典的空間變跡法(SVA)的幾何模型,通過(guò)使用模值濾波的方法使得每一像素點(diǎn)的能量最小,根據(jù)這一原則,計(jì)算出加權(quán)因子,接著提出了約束因子的概念,最后將加權(quán)因子與約束因子進(jìn)行比較,根據(jù)不同的比較結(jié)果,得出不同像素點(diǎn)的輸出值。該方法不僅使旁瓣的能量抑制到更低,而且擁有了更窄的主瓣,提高了SAR圖像的分辨率。于此同時(shí),該方法也存在一定的缺陷,該方法降低了整幅圖像的能量,換句話說(shuō)就是,處理后的圖像相比于原始圖像變得比較暗。所以,在應(yīng)用旁瓣抑制處理之后,為了解決圖像能量因旁瓣抑制而受影響的缺陷,又加入了SAR圖像背景濾波技術(shù)。首先,提取原始SAR圖像的背景,然后將已通過(guò)上述旁瓣抑制方法處理后的圖像中比較暗的背景替換為原始圖像的背景,通過(guò)上述處理就可以得到一幅高質(zhì)量,高分辨率的SAR圖像。本文工作得到了國(guó)家自然科學(xué)基金(No.61173092)、新世紀(jì)優(yōu)秀人才支持計(jì)劃(No.66ZY110)和陜西省科學(xué)技術(shù)研究發(fā)展計(jì)劃項(xiàng)目(No.2013KJXX-64)資助。
[Abstract]:Synthetic Aperture Radar (SAR), as a high-resolution imaging radar, plays an important role in the field of remote sensing imaging and is one of the important imaging tools. It can obtain high-quality and high-resolution images and is widely used in national defense and daily life. However, with the development of modern military weapons and the improvement of quality of life (QOL), SAR imaging technology and image processing technology has been a hot topic for scholars. So far, although many effective SAR imaging and image processing methods have been proposed in the field of radar imaging technology, but in practical applications, Because of the diversity of imaging target intensity and the complication of imaging scene, SAR imaging technology and image processing technology are still facing great challenges. This paper makes a detailed analysis and research on the situation where there are many strong target points in the scene. The main research results are as follows: 1. A polar coordinate format algorithm (MPFA) based on rotating coordinate system is proposed. This method is suitable for large squint. Based on Polar format algorithm (PFA), the coordinate of synthetic aperture radar (SAR) is recalculated in the rotating coordinate system by using the geometric coordinate system of SAR imaging. The distance between the radar and the target point is then obtained. Through the rotation of the geometric coordinate system, the geometric model in strabismus is transformed into the model in the positive side view. This method not only overcomes the defect that PFA is only suitable for the positive side view. Moreover, the imaging target is still a positive cross in the case of large squint, which lays a convenient foundation for the next SAR image sidelobe suppression. In this paper, a new method of spatial transformation based on modulus constraint (CMoSVA) is proposed. The method is based on the classical geometric model of SVA. The energy of each pixel is minimized by using the modular filtering method. According to this principle, the weighting factor is calculated, and the concept of constraint factor is proposed. Finally, by comparing the weighting factor with the constraint factor, the output values of different pixel points are obtained according to the different comparison results. This method not only reduces the energy of the sidelobe to a lower level, but also has a narrower main lobe, which improves the resolution of SAR images. At the same time, the method also has some defects, the method reduces the energy of the whole image, in other words, the processed image becomes darker than the original image. Therefore, after applying sidelobe suppression, in order to solve the problem that the image energy is affected by sidelobe suppression, the background filtering technology of SAR image is added. Firstly, the background of the original SAR image is extracted, then the dark background in the image processed by the sidelobe suppression method is replaced with the background of the original image, and a high quality image can be obtained by the above processing. High resolution SAR images. This work is supported by the National Natural Science Foundation of China (No. 61173092), the New Century Talent support Program (No. 66ZY110) and the Shaanxi Province Scientific and technological Research and Development Program (No. 2013KJXX-64).
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN957.52

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本文編號(hào)：2102322