【摘要】：數(shù)字高程模型(Digital Elevation Model,DEM)作為一種重要的地理空間數(shù)據(jù),在國(guó)民經(jīng)濟(jì)和國(guó)防建設(shè)以及人文和自然科學(xué)領(lǐng)域有著廣泛應(yīng)用。就我國(guó)而言,目前還沒(méi)有覆蓋全球的高精度DEM,加快推進(jìn)我國(guó)海洋國(guó)土乃至全球的高精度DEM獲取是《全國(guó)基礎(chǔ)測(cè)繪中長(zhǎng)期規(guī)劃綱要(2015——2030年)》的明確要求。野外數(shù)字測(cè)量、地形圖掃描數(shù)字化、攝影測(cè)量和機(jī)載Lidar等方法也可獲取局部高分辨率DEM,但均耗時(shí)耗力,易受云霧雨雪天氣影響,不適于大區(qū)域尤其是境外DEM的獲取。地面GPS的采樣點(diǎn)非常稀疏,成本很高,限制了其發(fā)展。重軌衛(wèi)星InSAR技術(shù)具有主動(dòng)成像、穿云透霧、全天時(shí)工作等特點(diǎn),成為大范圍獲取DEM的研究熱點(diǎn)。并且我國(guó)高分三號(hào)衛(wèi)星于2017年正式投入使用,獲取了首批高分辨率SAR影像,可為通過(guò)InSAR技術(shù)獲取國(guó)內(nèi)乃至全球的高精度DEM提供數(shù)據(jù)支持。為獲取更高精度的InSAR DEM,國(guó)內(nèi)外學(xué)者開(kāi)展了諸多嘗試,相關(guān)研究集中在三個(gè)方面:一是外部DEM(如SRTM DEM)輔助地形復(fù)雜區(qū)域干涉相位進(jìn)行相位解纏,降低解纏難度,減小解纏誤差,但沒(méi)考慮大氣相位噪聲的影響,也沒(méi)對(duì)完全失相干的水域進(jìn)行高精度探測(cè)及高程賦值;二是開(kāi)展多基線InSAR聯(lián)合估計(jì)DEM,通過(guò)冗余數(shù)據(jù)增加觀測(cè)次數(shù)以減小觀測(cè)誤差,提高DEM的精度,但沒(méi)充分考慮消除大氣相位噪聲的影響;三是時(shí)間序列InSAR技術(shù)正趨成熟,而國(guó)內(nèi)外學(xué)者多集中于提高反演地表形變的精度,利用反演的高程殘差獲取城區(qū)建筑物的高度信息也有少量研究,但基于高程殘差更新外部低精度DEM以獲取更高精度DEM的研究目前尚未見(jiàn)到。針對(duì)以上問(wèn)題,本文在常年云雨天氣、地形復(fù)雜、植被茂密的云南省昆明市高山地開(kāi)展重軌衛(wèi)星單基線InSAR、多基線InSAR獲取DEM研究;在地勢(shì)復(fù)雜、雨雪較多的遼寧省葫蘆島市北部低山丘陵區(qū)開(kāi)展時(shí)間序列InSAR更新DEM研究;用國(guó)家1:50000 DEM一級(jí)數(shù)據(jù)評(píng)定實(shí)驗(yàn)結(jié)果的高程精度。主要工作如下:一、開(kāi)展基于外部DEM輔助解纏的單基線InSAR技術(shù)研究。提出利用外部DEM恢復(fù)干涉相位整周模糊數(shù)的方法;改進(jìn)“二軌”差分輔助相位解纏的方法,稱之為“差分補(bǔ)償”法:一是基于差分相位的條紋頻率初次精化基線,二是對(duì)影像進(jìn)行水域探測(cè)及高程賦值。選用2景昆明市高山地區(qū)ALOS-2 PALSAR-2影像(20160701、20160729)開(kāi)展常規(guī)InSAR、外部DEM恢復(fù)干涉相位整周模糊數(shù)InSAR和“差分補(bǔ)償”InSAR的對(duì)比實(shí)驗(yàn)研究。結(jié)果表明:三種方法獲取的DEM精度均滿足國(guó)家1:100000DEM三級(jí)標(biāo)準(zhǔn);外部DEM恢復(fù)整周模糊數(shù)InSAR DEM精度最高,差分補(bǔ)償InSAR DEM次之,常規(guī)InSAR DEM最低;水域探測(cè)結(jié)果較為理想,精度較高。二、開(kāi)展多基線InSAR相位累積方法研究。提出干涉相位累積法和差分相位累積補(bǔ)償法;提出時(shí)序相位定權(quán)疊加法。選用4景昆明市高山地區(qū)ALOS-2 PALSAR-2影像(20160701、20160715、20160729、20160909)開(kāi)展實(shí)驗(yàn)研究。結(jié)果表明:相位累積法可顯著減弱大氣相位噪聲;由4景影像組構(gòu)的六基線相位累積獲取的InSAR DEM精度基本滿足美國(guó)DTED-1標(biāo)準(zhǔn)和國(guó)家1:50000 DEM三級(jí)標(biāo)準(zhǔn)。三、開(kāi)展時(shí)間序列InSAR更新DEM方法研究。時(shí)間序列InSAR技術(shù)通過(guò)提取高密度高質(zhì)量的穩(wěn)定點(diǎn)目標(biāo),有效地克服了傳統(tǒng)InSAR的大氣效應(yīng)、時(shí)間去相干、基線去相干等因素的影響,可高精度地獲取點(diǎn)目標(biāo)上的地表形變和外部DEM高程殘差信息。對(duì)點(diǎn)目標(biāo)的高程殘差做空間插值處理,得到全監(jiān)測(cè)區(qū)的高程殘差信息,以此更新外部DEM高程。選用22景葫蘆島市低山丘陵區(qū)ALOS-1 PALSAR-1影像開(kāi)展試驗(yàn)性探究,提取了圖像像點(diǎn)占比約為6.34%的高相干點(diǎn)目標(biāo)及其高程殘差,并進(jìn)行克里金插值。選取范圍為9 km×9 km、地勢(shì)陡峭、植被較密、無(wú)人工建/構(gòu)筑物、無(wú)地面沉降的小區(qū)域進(jìn)行重點(diǎn)分析。結(jié)果表明:SRTM DEM更新后,高程精度提高了15.6%。
[Abstract]:Digital Elevation Model (DEM), as an important geospatial data, is widely used in national economy and national defense construction, as well as in the fields of human and natural science. As far as our country is concerned, the global high-precision DEM has not yet been covered, and the high-precision DEM acquisition of China's marine land and even the whole world is a clear requirement for the national basic and long-term plan for long-and long-term planning (2015 _ 2030). The local high-resolution DEM can also be obtained by field digital measurement, topographic map scanning digitization, photogrammetry, and on-board Lidar. However, it is time-consuming and easy to be affected by the cloud and snow weather, and is not suitable for the acquisition of large area, especially the overseas DEM. The ground GPS sampling point is very sparse, the cost is high, and its development is limited. The heavy-orbit satellite InSAR technology has the characteristics of active imaging, cloud-penetrating, full-day operation and so on, and becomes a hot spot for the large-scale acquisition of DEM. and the first batch of high-resolution SAR images is obtained by the high-resolution satellite 3 in 2017, and can be used for providing data support for high-precision DEM obtained at home and even in the world through the InSAR technology. In order to obtain the more accurate InSAR DEM, the domestic and foreign scholars have made a number of attempts, and the relevant research has focused on three aspects: one is the external DEM (such as the SRTM DEM) to assist in the phase unwrapping of the complex area interference phase, to reduce the difficulty of the solution and to reduce the unwrapping error. but the influence of the atmospheric phase noise is not taken into consideration, and the high-precision detection and the elevation assignment are not carried out on the fully distorted water area; secondly, the multi-baseline InSAR combined estimation DEM is carried out, the observation times are increased by the redundant data to reduce the observation error, and the accuracy of the DEM is improved, but the effect of eliminating the atmospheric phase noise is not fully considered; the three is that the time series InSAR technology is becoming more mature, and the domestic and foreign scholars are more focused on improving the accuracy of the inversion of the surface deformation, However, the method of updating the external low-precision DEM based on the elevation residual is not seen at present. In view of the above problems, in this paper, a single-baseline InSAR, a multi-baseline InSAR, a multi-baseline InSAR, is used to study the single-baseline InSAR and multi-baseline InSAR in the high mountainous area of Kunming, which is a complex and dense vegetation. The time series InSAR is used to update the DEM for the low mountain area in the northern part of Huludao City, Liaoning Province, and the elevation accuracy of the experimental results is evaluated by the first-level data of the national 1: 50000 DEM. The main work is as follows: 1. Carry out the single-baseline InSAR technology research based on the auxiliary unwrapping of the external DEM. This paper presents a method to recover interference phase integer ambiguity by using external DEM, and to improve the 鈥渢wo-track鈥，

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