基于無人飛艇低空航測系統(tǒng)建筑物紋理獲取與處理技術(shù)
發(fā)布時間：2018-08-14 12:43
【摘要】：自美國前副總統(tǒng)戈爾1998年提出“數(shù)字地球”概念以來,世界上許多國家都不約而同的以城市作為主要切入點之一,關(guān)于“數(shù)字城市”的理論與框架體系研究一直為地理信息科學(xué)領(lǐng)域的熱點。隨著當(dāng)今物聯(lián)網(wǎng)、云計算的飛速發(fā)展,作為新一代信息支持的“智慧城市”對高分辨率遙感數(shù)據(jù)需求與日俱增,最快最準(zhǔn)確地獲取基礎(chǔ)地理數(shù)據(jù)是國家基本建設(shè)和信息化進(jìn)程的首要問題。 近幾年低空遙感技術(shù)發(fā)展很快,它彌補(bǔ)了衛(wèi)星遙感和中高空航測在及時性與精細(xì)度(影像精細(xì)度包括厘米級精細(xì)度和建筑物三維精細(xì)度)方面的不足。現(xiàn)有的低空航測多為輕小型固定翼無人機(jī)搭載單個數(shù)碼相機(jī),雖然具有光度學(xué)方面的光能量優(yōu)勢,但也有幾何學(xué)方面的窄像幅劣勢,這種劣勢不僅使得作業(yè)效率低,更重要的是,它導(dǎo)致航測精度降低。為了解決此精度低下的問題,根本之路是使用寬角相機(jī)。而國內(nèi)外成熟的組合寬幅面相機(jī)一方面缺乏無人機(jī)平臺上應(yīng)用的客觀基礎(chǔ),另一反面由于受航高和空間攝影姿態(tài)限制(垂直或小角度攝影),僅能獲得部分主體建筑的高度信息和頂部紋理信息,難以滿足城市建筑物三維數(shù)據(jù)獲取的要求。 本文結(jié)合新近發(fā)展的多傳感器集成技術(shù),研究適應(yīng)于無人機(jī)低空航測的組合寬幅面、寬視場角的航空相機(jī)(本文稱紋理相機(jī)),通過快速安全地采集城市建筑物三維信息,建立鑲嵌有影像紋理的真實感城市三維模型。其主要研究內(nèi)容如下： (1)大比例尺低空傾斜航測飛行系統(tǒng)選擇和傳感器系統(tǒng)設(shè)計。首先,分析影響大比例尺低空傾斜航測獲取多視、高清晰度和大比例尺測量精度影像的因素,作為大比例尺低空航測飛行系統(tǒng)選擇和傳感器系統(tǒng)設(shè)計的依據(jù)。分析可知,要想獲取高分辨率、高清晰度影像,選擇的飛行器必須飛得低飛得慢,從而選擇無人飛艇低空航測系統(tǒng)作為城市三維建模主要數(shù)據(jù)源獲取的遙感平臺,分析了其優(yōu)勢所在,并簡述系統(tǒng)的組成設(shè)計。在此基礎(chǔ)上,研究和設(shè)計了適應(yīng)于無人飛艇的輕小型組合寬角相機(jī)系統(tǒng),包括紋理相機(jī)模型設(shè)計和穩(wěn)定平臺設(shè)計。 (2)基于紋理相機(jī)系統(tǒng)的低空航測精度分析及提高方法研究。首先,分析與寬角成像有關(guān)的精度問題,包括相對定向精度和測圖精度。分析表明,低空航測的精度與所用相機(jī)的像場角有很大關(guān)系,因此低空航測應(yīng)盡可能使用寬角相機(jī)�；诖私Y(jié)論,針對研制的適用于低空輕荷載無人機(jī)的紋理相機(jī)如何提高航測精度過程進(jìn)行研究,包括有效像幅判斷、自檢校自穩(wěn)定技術(shù)、采用大重疊度航空攝影的作業(yè)方法。最后,通過實驗對比論證利用寬角相機(jī)進(jìn)行大重疊度低空航測,可以有效提高成果精度。 (3)研究了基于紋理相機(jī)影像的紋理提取方法,包括建筑物輪廓線與影像配準(zhǔn)的自動快速方法和半自動方法。首先,根據(jù)建筑物邊界多以直線表達(dá),因此如何精確獲取影像上建筑物邊緣的直線特征是解決紋理提取的關(guān)鍵所在。提出了利用Canny算子進(jìn)行邊緣提取,通過角度和距離限制,利用帶權(quán)置信度獲取最佳影像邊緣線的自動快速方法。此外,考慮到在多幅影像中建立建筑物空間輪廓線與其影像直線特征映射關(guān)系的復(fù)雜性,對通過影像直線特征同名匹配來提高映射關(guān)系建立半自動化程度的可能性進(jìn)行了探討,提出了基于多視幾何約束(核線約束、三視張量約束、相似性約束)的影像直線特征同名匹配策略。最后,對多紋理影像進(jìn)行優(yōu)選算法研究并進(jìn)行幾何糾正處理。 (4)研究了建筑物立面紋理顏色優(yōu)化方法,包括紋理影像模糊消除和相鄰影像色調(diào)一致性處理。首先,分析了紋理影像模糊現(xiàn)象產(chǎn)生的原因,包括噪聲影響、影像像移以及幾何糾正內(nèi)插處理等。在對比現(xiàn)有圖像復(fù)原算法優(yōu)缺點基礎(chǔ)上,提出了基于高頻強(qiáng)調(diào)的MTF的圖像復(fù)原算法,實現(xiàn)了利用刃邊邊緣圖像數(shù)據(jù)估計MTF曲線,避免反復(fù)估計PSF過程,根據(jù)影像質(zhì)量評價標(biāo)準(zhǔn)評定了該方法的有效性。其次,根據(jù)建筑物紋理構(gòu)建中,存在單個建筑物各個面色彩斑駁,相鄰建筑物色彩過渡不自然的情況,提出了基于紋理相機(jī)影像的主色調(diào)匹配方法,使偏暗或偏亮的影像得以糾正,處理后的紋理影像色調(diào)基本一致,達(dá)到三維城市視覺上的一致性和美觀性效果。
[Abstract]:Since former US Vice President Gore put forward the concept of "Digital Earth" in 1998, many countries in the world have taken cities as one of the main entry points. The research on the theory and framework system of "Digital City" has been a hot topic in the field of geographic information science. The demand for high-resolution remote sensing data is increasing day by day in the new generation of "smart cities" supported by information. It is the most important problem for national capital construction and informatization process to obtain basic geographic data quickly and accurately.
In recent years, low-altitude remote sensing technology has developed rapidly, which makes up for the shortcomings of satellite remote sensing and mid-altitude aerial survey in timeliness and precision (image precision includes centimeter-level precision and building three-dimensional precision). In order to solve this problem, the fundamental way is to use wide-angle cameras. On the one hand, the mature combination wide-width cameras at home and abroad lack the application on UAV platforms. On the other hand, due to the limitation of altitude and space photographic attitude (vertical or small angle photography), only the height information and the top texture information of some main buildings can be obtained, which is difficult to meet the requirements of 3D data acquisition of urban buildings.
In this paper, combining with the recent development of multi-sensor integration technology, a combined wide-width, wide-field-of-view aerial camera (texture camera) suitable for low-altitude aerial survey of unmanned aerial vehicles (UAVs) is studied. By collecting the three-dimensional information of urban buildings quickly and safely, a realistic city three-dimensional model with image texture is built. :
(1) Selection of large-scale low-altitude tilt aerial survey flight system and design of sensor system. Firstly, the factors affecting the large-scale low-altitude tilt aerial survey to obtain multi-view, high-definition and large-scale measurement accuracy images are analyzed as the basis for large-scale low-altitude aerial survey flight system selection and sensor system design. Taking high-resolution and high-definition images, the selected aircraft must fly low and slow, so the unmanned airship low-altitude aerial survey system is selected as the remote sensing platform for urban three-dimensional modeling. Its advantages are analyzed and the composition and design of the system are briefly described. On this basis, the lightness suitable for unmanned airship is studied and designed. Small combined wide-angle camera system, including texture camera model design and stable platform design.
(2) The analysis and improvement of low altitude aerial survey accuracy based on texture camera system. Firstly, the precision problems related to wide angle imaging, including relative orientation accuracy and mapping accuracy, are analyzed. The analysis shows that the accuracy of low altitude aerial survey is closely related to the field angle of the camera used, so the wide angle camera should be used as far as possible in Low Altitude Aerial survey. The conclusion is that the texture camera suitable for low altitude light-load UAV can improve the aerial survey accuracy, including effective image amplitude judgment, self-calibration and self-stabilization technology, and the method of aerial photography with large overlap. Effectively improve the accuracy of the results.
(3) Texture extraction methods based on texture cameras are studied, including automatic, fast and semi-automatic methods for building contour and image registration. Firstly, according to the fact that building boundaries are mostly expressed in straight lines, how to accurately obtain the linear features of building edges on images is the key to texture extraction. Canny operator is used to extract the edge of the image, and the weighted confidence is used to obtain the best image edge line. In addition, considering the complexity of mapping between the building spatial contour and the image linear feature in multiple images, the mapping level is improved by matching the image linear feature with the same name. This paper discusses the possibility of establishing semi-automation degree, and proposes an image line feature homonymy matching strategy based on multi-view geometric constraints (kernel-line constraints, three-view tensor constraints, similarity constraints).
(4) The texture color optimization methods of building elevation are studied, including texture image blur elimination and adjacent image tone consistency processing. Firstly, the causes of texture image blur are analyzed, including noise, image motion and geometric correction interpolation. An image restoration algorithm based on high-frequency emphasized MTF is proposed, which uses edge image data to estimate MTF curve and avoids repeated estimation of PSF process. The effectiveness of this method is evaluated according to image quality evaluation criteria. Secondly, according to building texture construction, there are color mottles on each surface of a single building, and adjacent buildings have color overlap. In order to correct the dark or bright images, a method of main tone matching based on texture camera image is proposed. The color of texture image after processing is basically the same, which achieves the consistency and aesthetic effect of 3D city vision.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：P231
本文編號：2182899
[Abstract]:Since former US Vice President Gore put forward the concept of "Digital Earth" in 1998, many countries in the world have taken cities as one of the main entry points. The research on the theory and framework system of "Digital City" has been a hot topic in the field of geographic information science. The demand for high-resolution remote sensing data is increasing day by day in the new generation of "smart cities" supported by information. It is the most important problem for national capital construction and informatization process to obtain basic geographic data quickly and accurately.
In recent years, low-altitude remote sensing technology has developed rapidly, which makes up for the shortcomings of satellite remote sensing and mid-altitude aerial survey in timeliness and precision (image precision includes centimeter-level precision and building three-dimensional precision). In order to solve this problem, the fundamental way is to use wide-angle cameras. On the one hand, the mature combination wide-width cameras at home and abroad lack the application on UAV platforms. On the other hand, due to the limitation of altitude and space photographic attitude (vertical or small angle photography), only the height information and the top texture information of some main buildings can be obtained, which is difficult to meet the requirements of 3D data acquisition of urban buildings.
In this paper, combining with the recent development of multi-sensor integration technology, a combined wide-width, wide-field-of-view aerial camera (texture camera) suitable for low-altitude aerial survey of unmanned aerial vehicles (UAVs) is studied. By collecting the three-dimensional information of urban buildings quickly and safely, a realistic city three-dimensional model with image texture is built. :
(1) Selection of large-scale low-altitude tilt aerial survey flight system and design of sensor system. Firstly, the factors affecting the large-scale low-altitude tilt aerial survey to obtain multi-view, high-definition and large-scale measurement accuracy images are analyzed as the basis for large-scale low-altitude aerial survey flight system selection and sensor system design. Taking high-resolution and high-definition images, the selected aircraft must fly low and slow, so the unmanned airship low-altitude aerial survey system is selected as the remote sensing platform for urban three-dimensional modeling. Its advantages are analyzed and the composition and design of the system are briefly described. On this basis, the lightness suitable for unmanned airship is studied and designed. Small combined wide-angle camera system, including texture camera model design and stable platform design.
(2) The analysis and improvement of low altitude aerial survey accuracy based on texture camera system. Firstly, the precision problems related to wide angle imaging, including relative orientation accuracy and mapping accuracy, are analyzed. The analysis shows that the accuracy of low altitude aerial survey is closely related to the field angle of the camera used, so the wide angle camera should be used as far as possible in Low Altitude Aerial survey. The conclusion is that the texture camera suitable for low altitude light-load UAV can improve the aerial survey accuracy, including effective image amplitude judgment, self-calibration and self-stabilization technology, and the method of aerial photography with large overlap. Effectively improve the accuracy of the results.
(3) Texture extraction methods based on texture cameras are studied, including automatic, fast and semi-automatic methods for building contour and image registration. Firstly, according to the fact that building boundaries are mostly expressed in straight lines, how to accurately obtain the linear features of building edges on images is the key to texture extraction. Canny operator is used to extract the edge of the image, and the weighted confidence is used to obtain the best image edge line. In addition, considering the complexity of mapping between the building spatial contour and the image linear feature in multiple images, the mapping level is improved by matching the image linear feature with the same name. This paper discusses the possibility of establishing semi-automation degree, and proposes an image line feature homonymy matching strategy based on multi-view geometric constraints (kernel-line constraints, three-view tensor constraints, similarity constraints).
(4) The texture color optimization methods of building elevation are studied, including texture image blur elimination and adjacent image tone consistency processing. Firstly, the causes of texture image blur are analyzed, including noise, image motion and geometric correction interpolation. An image restoration algorithm based on high-frequency emphasized MTF is proposed, which uses edge image data to estimate MTF curve and avoids repeated estimation of PSF process. The effectiveness of this method is evaluated according to image quality evaluation criteria. Secondly, according to building texture construction, there are color mottles on each surface of a single building, and adjacent buildings have color overlap. In order to correct the dark or bright images, a method of main tone matching based on texture camera image is proposed. The color of texture image after processing is basically the same, which achieves the consistency and aesthetic effect of 3D city vision.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：P231
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