本文選題：航空影像 + 全局一致�。� 參考：《武漢大學(xué)》2017年碩士論文

【摘要】：近年來,基于星載和機(jī)載平臺的遙感成像技術(shù)在地面數(shù)據(jù)快速獲取、國土資源監(jiān)測等應(yīng)用領(lǐng)域有著重要地位。而實(shí)際作業(yè)過程中,研究區(qū)域涉及的范圍往往不是一幅影像所能覆蓋的,需要將多幅影像進(jìn)行拼接形成具有較寬視角的高分辨率合成影像,以滿足全局分析和整體解譯等應(yīng)用的需求。航空影像拼接技術(shù)流程主要包括幾何對齊、色彩一致性處理,拼接線選取和邊界融合四個(gè)環(huán)節(jié)。本文針對低空無人機(jī)影像序列快速無控拼接方法中的具有挑戰(zhàn)性的幾何對齊和顏色一致性校正兩個(gè)算法模塊進(jìn)行研究。全局一致對齊。為了解決低空攝影條件下地面?zhèn)纹矫嫘詭淼挠跋衿唇永鄯e透視變形問題,本文提出了一種能在抑制全局透視變形的同時(shí)保證局部拼接精度的通用拼接框架。首先,利用影像序列的時(shí)序關(guān)系進(jìn)行嘗試拼接,同時(shí)利用逐步恢復(fù)的相對幾何位置探測并驗(yàn)證潛在的影像重疊關(guān)系,以獲取更為完整的影像鄰接拓?fù)渚W(wǎng)。特別地,無序影像數(shù)據(jù)可以預(yù)先通過從快速構(gòu)建的影像相似表搜索出連通所有影像的主鏈轉(zhuǎn)化為有序序列。然后,基于估計(jì)的影像鄰接拓?fù)渚W(wǎng),利用多源最短路徑算法搜索出具有最少誤差傳遞次數(shù)的參考影像,并將所有影像組織成一棵分級生成樹。最后,以拓?fù)浞治鱿路纸M估計(jì)的仿射變換模型作為初始模型參數(shù),在基于單應(yīng)模型的全局優(yōu)化能量方程中加入抗透視畸變的約束項(xiàng),以保持局部對齊精度與全局一致性之間的最佳平衡。顏色一致性校正。本文提出了一種有效的顏色校正方法,設(shè)計(jì)的能量函數(shù)能在最小化影像間顏色差異的同時(shí)兼顧單張影像的梯度保護(hù)和對比度優(yōu)化。該方法首先利用變化檢測算法識別內(nèi)容變化區(qū)域以消除它對影像間對應(yīng)顏色提取的干擾。然后,通過二次樣條曲線對灰度映射關(guān)系的直接建模,將顏色一致性、動(dòng)態(tài)范圍以及梯度保護(hù)等質(zhì)量約束有效地整合到統(tǒng)一的能量框架下。最后經(jīng)凸二次規(guī)劃快速地求解全局優(yōu)化函數(shù),并能保證解的全局最優(yōu)性。對于全局一致拼接算法的測試,本文選取了兩組覆蓋范圍較廣的大規(guī)模低空無人機(jī)影像影像作為測試數(shù)據(jù)。實(shí)驗(yàn)結(jié)果表明,本文提出的算法能在保證影像序列拼接結(jié)果的全局一致性的同時(shí),獲得明顯優(yōu)于商業(yè)軟件PTGui的局部拼接精度。此外,為了更加全面地測試本文顏色一致性處理算法的有效性,本文分選取了多時(shí)相衛(wèi)星影像和航空影像的遙感數(shù)據(jù)集作為測試數(shù)據(jù)。通過與同類算法的對比,實(shí)驗(yàn)結(jié)果從定性和定量兩方面證明了本文算法在影像拼接中對顏色一致性校正問題的有效性。
[Abstract]:In recent years, the remote sensing imaging technology based on spaceborne and airborne platform plays an important role in the field of rapid acquisition of ground data and monitoring of land resources.However, in the process of practical operation, the range of research area is often not covered by one image, so it is necessary to splice multiple images to form high-resolution composite images with wide angle of view.To meet the needs of global analysis and global interpretation and other applications.The technical flow of aviation image stitching mainly includes four links: geometric alignment, color consistency processing, stitching line selection and boundary fusion.In this paper, the challenging algorithms of geometric alignment and color consistency correction for image sequences of low altitude UAV are studied.Global consistent alignment.In order to solve the problem of image stitching cumulative perspective deformation caused by the pseudo-planarity of the ground under low altitude photography, this paper presents a universal mosaic framework which can suppress the global perspective deformation while ensuring the local stitching accuracy.Firstly, the sequential relation of image sequence is used to try to splice, and the potential image overlap relationship is detected and verified by using the gradually restored relative geometric position to obtain a more complete image adjacent topology network.In particular, the unordered image data can be pre-searched from the rapidly constructed image similarity table to transform the main chain of all the images into an ordered sequence.Then, based on the estimated image adjacent topology network, the multi-source shortest path algorithm is used to search the reference images with minimum error transfer times, and all the images are organized into a hierarchical spanning tree.Finally, taking the affine transformation model of grouping estimation under topological analysis as the initial model parameter, the global optimization energy equation based on the monoclinic model is added to the global optimization energy equation with constraints against perspective distortion.In order to maintain the best balance between local alignment accuracy and global consistency.Color consistency correction.In this paper, an effective color correction method is proposed. The designed energy function can minimize the color difference between images while taking into account the gradient protection and contrast optimization of single image.Firstly, the change detection algorithm is used to identify the region of content change to eliminate the interference to the corresponding color extraction between images.Then, through the direct modeling of the gray mapping relation by the quadratic spline curve, the quality constraints such as color consistency, dynamic range and gradient protection are effectively integrated into the unified energy framework.Finally, the global optimization function is solved quickly by convex quadratic programming, and the global optimality of the solution is guaranteed.In this paper, two sets of large scale low altitude UAV images covering a wide range are selected as test data for the test of global consistent stitching algorithm.The experimental results show that the proposed algorithm can ensure the global consistency of the image sequence stitching results and obtain the local stitching accuracy which is obviously superior to the commercial software PTGui.In addition, in order to test the validity of the algorithm, the remote sensing data sets of multitemporal satellite images and aerial images are selected as the test data.Compared with the similar algorithms, the experimental results demonstrate the effectiveness of the proposed algorithm in color consistency correction in image stitching from both qualitative and quantitative aspects.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TP751

【參考文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 黃登山;像素級遙感影像融合方法研究[D];中南大學(xué);2011年

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本文編號：1761146