外文翻譯---GPS的精密單點定位技術(shù)在空中三角測量的應(yīng)用

1、.附錄1：英文原文ISPRS Journal of Photogrammetry and Remote SensingYUAN Xiu-xiao(袁繡蕭)FU Jan-hong(福劍虹)SUN Hong-xing( 孫紅星)The application of GPS precise point positioning technology in aerial triangulation AbstractIn traditional GPS-supported aero triangulation, differential GPS (DGPS) positioning technology

2、is used to determine the 3-dimensional coordinates of the perspective centers at exposure time with an accuracy of centimeter to decimeter level. This method can significantly reduce the number of ground control points (GCPs).However, the establishment of GPS reference stations for DGPS positioning

3、is not only labor-intensive and costly, but also increases the implementation difficulty of aerial photography. This paper proposes aerial triangulation supported with GPS precise point positioning (PPP) as a way to avoid the use of the GPS reference stations and simplify the work of aerial photogra

4、phy. Firstly, we present the algorithm for GPS PPP in aerial triangulation applications. Secondly, the error law of the coordinate of perspective centers determined using GPS PPP is analyzed. Thirdly, based on GPS PPP and aerial triangulation software self-developed by the authors, four sets of actu

5、al aerial images taken from surveying and mapping projects, different in both terrain and photographic scale, are given as experimental models. The four sets of actual data were taken over a flat region at a scale of 1:2500, a mountainous region at a scale of 1:3000, a high mountainous region at a s

6、cale of 1:32000 and an upland region at a scale of 1:60000 respectively. In these experiments, the GPS PPP results were compared with results obtained through DGPS positioning and traditional bundle block adjustment. In this way, the empirical positioning accuracy of GPS PPP in aerial triangulation

7、can be estimated. Finally, the results of bundle block adjustment with airborne GPS controls from GPS PPP are analyzed in detail.The empirical results show that GPS PPP applied in aerial triangulation has a systematic error of half-meter level and a stochastic error within a few decimeters. However,

8、 if a suitable adjustment solution is adopted, the systematic error can be eliminated in GPS-supported bundle block adjustment. When four full GCPs are emplaced in the corners of the adjustment block, then the systematic error is compensated using a set of independent unknown parameters for each str

9、ip, the final result of the bundle block adjustment with airborne GPS controls from PPP is the same as that of bundle block adjustment with airborne GPS controls from DGPS. Although the accuracy of the former is a little lower than that of traditional bundle block adjustment with dense GCPs, it can

10、still satisfy the accuracy requirement of photogrammetric point determination for topographic mapping at many scales. ' 2009 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved.Key words: deformation monitoring; landslide; sin

11、gle epoch GPS positioning; ambiguity resolutionIntroductionAerial triangulation (AT) is the basicmethod for analyzing aerial images in order to calculate the 3-dimensional coordinates of object points and the exterior orientation elements of images. Up until now, bundle block adjustment has been com

12、monly employed for AT, and numerous ground control points (GCPs) are necessary for the adjustment computation (Wang, 1990). In the 1950s, photogrammetrists began exploiting other auxiliary data to reduce the number of GCPs. However, investigation did not achieve an implementing result because of the

13、many technological limitations at that time (Li and Shan, 1989). In the 1970s, with the application of Global Positioning System (GPS), the situation changed a lot. GPS can provide 3-dimensional coordinates of surveying points with centimeter accuracy in differential mode, it was therefore applied i

14、n AT to measure the spatial position coordinates of the projection centers (referred to as GPS camera stations or airborne GPS control points). In this way, the number of GCPs could be significantly reduced. Block adjustment of combined photogrammetric observations and GPS-determined positions of pe

15、rspective centers is regarded as GPS-supported AT. Since the beginning of the 1980s, many papers have presented the significant research and experimental results of GPS-supported AT (Ackermann, 1984; Friess, 1986; Lucas, 1987). After about 20 years of these efforts, GPS-supported AT was extensively

16、applied in aerial triangulation at many scales and in all types of terrain. It is particularly beneficial in areas where they are difficult to establish ground control (Ackermann, 1994). In the late 1990s, with the development of sensor technology, an integrated systemof GPS / Inertial Navigation Sy

17、stem(POS)was first used in AT to obtain the position and attitude information of aerial images directly. This technology, in theory, can eliminate the need for GCPs. However, research indicates that the digital orthophoto map can be made directly by image orientation parameters obtained via a POS (C

18、annon and Sun, 1996; Cramer et al., 2000; Heipke et al., 2001), but there will be larger vertical parallax when stereo models are reconstructed using these image orientation parameters and the height accuracy cannot satisfy the requirement of large scale topographic mapping. Therefore, a bundle bloc

19、k adjustment should be made, combined image orientation parameters obtained via the POS and photogrammetric observations (Greening et al., 2000). Whether exploiting GPS data or POS data in AT, DGPS positioning is necessary to provide the GPS camera stations at present. In the DGPS mode, one or more

20、GPS reference stations should be emplaced on the ground and observed synchronously and continuously together with the airborne GPS receiver during the entire flight mission. Additionally, signals from GPS satellites should be received as few transmission interruptions as possible. Initialization sur

21、veying is also required before aircraft takes off and static surveying should be performed after landing. In the processing of GPS observations, carrier phase differential technique is used to eliminate or reduce GPS positioning errors, including satellite clock error, satellite orbit error, atmosph

22、eric delay error, and so on. Generally speaking, it is difficult to emplace proper GPS reference stations when the aerial photographic region is with large scope or difficult to access and communicate. In order to guarantee the quality of aerial images, a survey area must be photographed for a long

23、period, which is result from the shortage of weather suitable for photography. GPS reference stations must therefore remain in place for a long time. Moreover, the accuracy of DGPS positioning is relevant to the length of baseline. The longer the baseline, the weaker the correlation between ionosphe

24、ric refraction error and tropospheric delay error. Due to the need for spatial correlation of atmospheric delay errors, the lengths of GPS differential baselines are typically limited to within 20 km if centimeter level accuracy is required with high reliability (Sun, 2004). When it comes to aerial

25、photogrammetry, this is difficult because the length of survey areas is typically more than 200 km and the distance between the survey area and the airport may be greater. For baselines with long length, the atmospheric delay mainly composed of ionospheric delay and tropospheric delay will degrade p

26、ositioning accuracy significantly. In such cases, even the ionospheric delay can be almost removed by using dual frequency GPS receivers. However, there can still be a tropospheric delay within a few decimeters, meaning that for long baselines, the positioning accuracy is typically in the level of d

27、ecimeters. At the same time, the establishment of GPS reference stations sometimes makes the implementation of a survey plan difficult due to traffic, communication and cost considerations. As a result, the method of replacing GPS reference stations by Continuous Operating Reference Stations (CORS)

28、was proposed and obtained an accuracy in decimeter level compared with the results obtained by GPS reference stations (Bruton et al., 2001;Mostafa and Hutton, 2001). There are, however, no CORS in most of the survey areas, so this method cannot be applied extensively. With the development of GPS tec

29、hnology, the number of CORS is increasing all over the world and their distribution is more and more reasonable. International GNSS Service (IGS) can provide precise satellite orbit and clock error products with accuracies of 5 cm and 0.1 ns (3 cm). Utilizing IGS products, if the atmospheric delay e

30、rror can be removed, modeled or estimated at the centimeter level, it will be possible to obtain centimeter level positioning accuracy with only the observation of a single GPS receiver. Zumberge et al. presented a GPS precise point positioning (PPP) method based on an un-differenced mode and achiev

31、ed centimeter level accuracy for static positioning (Zumberge et al., 1997, 1998). Later, Muellerchoen et al. presented a method for realizing GPS global precise real time kinematic positioning by using single epoch un-differenced dual frequency observations after initialization (Muellerchoen et al.

32、, 2000). In this way, centimeter to decimeter level accuracy can be achieved for aerial GPS kinematic positioning at present (Gao and Chen, 2004; Zhang et al., 2006). If GPS PPP technology is applied in GPS-supported AT, only one GPS receiver is mounted on the aircraft and GPS reference stations on

33、the ground are no longer required. GPS-supported AT can therefore be implemented very easily andwith great flexibility, which is obviously significant in large survey blocks or areas with difficult terrain. Therefore, GPS PPP technology is discussed in this paper based on the highly dynamic characte

34、ristic of aerial remote sensing. The error law of GPS camera stations obtained by this method is analyzed, and the positioning accuracy and the feasibility of GPS-supported AT using GPS PPP technology are discussed. The goal of this work is to eliminate the need for the GPS reference stations in GPS

35、-supported aerial photography by the GPS PPP technology. This technology can not only reduce the cost of aerial photography but also increase the flexibility of aerial photographic operations,which is beneficial to thewidespread use of GPS-supported AT. 2. GPS precise point positioning for aerial tr

36、iangulation In contrast to DGPS positioning technology, GPS PPP is a type of absolute GPS positioning which uses IGS precise orbit parameters and clock error products. The main algorithms and correction models for the GPS PPP have been discussed in many papers (Han et al., 2001; Kouba and Heroux, 20

37、01; Holfmann et al., 2003; Chen et al., 2004) and the most widely used data type is un-differenced ionosphere-free carrier phase measurements, or an ionosphere- free combination with carrier phase and code pseudorange measurements. An alternative data type used by some studies is code-phase ionosphe

38、re-free combination that aims at accelerating the convergence speed for parameter solutions (Gao and Chen, 2004). In this paper, the single difference model is employed for reasons that will be discussed below. For simplification, error corrections including relativity, satellite phase center offset

39、, satellite wind up, earth body tide, ocean load correction and so on, will not be discussed here. The original un-differenced data type is formed by an ionosphere-free combination of dual frequency GPS data (Kouba and Heroux, 2001): (A-1)Here, j denotes satellite; Q j is the ionosphere-free combina

40、tion of L1 and L2 code pseudorange; j is the geocentric distance from the GPS receiver to the satellite j; dt is the GPS receiver clock error; dt j is the clock error of the satellite j, which can be obtained from IGS products; c is the vacuum speed of light; T is the zenith tropospheric delay; Mj i

41、s the mapping function of tropospheric delay for satellite j, for which several models can be used; j is the ionosphere-free combination of L1 and L2 carrier phase; Nj is the non-integer ambiguity of ionosphere-free carrier phase combination; "Q and "are the noises. There are five unknown

42、parameters in Eq. (1), including the 3-dimensional spatial coordinates of the receiver (X; Y; Z) lying in j , the zenith tropospheric delay T and the receiver clock error dt. Furthermore, in Eq. (2), besides the same parameters in Eq. (1), the ambiguity Nj is unknown. For these unknown parameters, t

43、he ambiguity Nj is constant if the cycle slip is repaired and the zenith tropospheric delay T changes very slowly or remains unchanged over a short time span, for example, over two hours. The receiver clock error dt changes very quickly and the coordinates of the receiver (X; Y; Z) are dependent on

44、the vehicle movement status. In aerial photogrammetric applications, the craft often carries out large maneuvers, the sequential filter based on the dynamic models of all parameters (Kouba and Heroux, 2001) can not be implemented for high accurate positioning because the process noises of the vehicl

45、e movement and the receiver clock error are very large. In this case, the recursive least squares algorithm can be used to separate the receiver coordinate and clock error from other parameters which remain constant or change very slowly (Chen et al., 2004). Assuming that X and Y are the two kinds o

46、f parameters to be estimated, the observation equation in matrix Form can be written as : (A-2) where L is observation vector; X is correction vector of the coordinates of GPS receiver antenna phase center and clock error; Y is vector of ambiguity parameters and the correction parameters to zenith t

47、ropospheric delay; A and B are design matrices; " is the noise vector; 0 is the standard deviation of the noise; P is the weight matrix of observations. 附錄2：中文翻譯GPS的精密單點定位技術(shù)在空中三角測量的應(yīng)用袁繡蕭 福劍虹 孫紅星摘 要 在傳統(tǒng)的GPS輔助空中三角測量,差分全球定位系統(tǒng)（DGPS）定位技術(shù)用于確定曝光時間透視中心的3維坐標厘米到分米級精度。這種方法可以大大減少地面控制點控制點的數(shù)量。但是DGPS定位的GPS基準站

48、的建立不僅勞動密集和昂貴的但同時也增加了航拍的實施難度。本文建議空中三角GPS精密單點定位的方式以避免使用的GPS基準站和簡化的航拍工作PPP的支持。首先我們提出了在空中三角測量應(yīng)用中的GPS的單點定位技術(shù)算法。其次使用GPS的PPP確定的角度中心的坐標錯誤的法律進行了分析。第三四套測繪項目的實際空中拍攝的圖像不同的地形和攝影的比例基于GPS的單點定位技術(shù)和由作者自行研制的空中三角測量軟件給出了實驗?zāi)Ｐ?。平坦地區(qū)為1:2500 的比例一個多山的地區(qū)為1:3000的比例在高山區(qū)和高地地區(qū)比例分別為1:32000和1:60000。在這些實驗中GPS的PPP結(jié)果進行比較結(jié)果獲得通過DGPS定位和傳統(tǒng)

49、的平差。在這樣的GPS的單點定位技術(shù)的實證定位在空中三角測量精度可以估算的。最后從GPS的單點定位技術(shù)的機載GPS控制的平差結(jié)果進行了詳細分析。實證結(jié)果表明PPP的GPS空中三角測量應(yīng)用有一個半米高的水平和幾個分米內(nèi)的隨機誤差的系統(tǒng)誤差。然而如果采用了適當?shù)恼{(diào)整解決方案系統(tǒng)誤差可以消除GPS平差。當四個完整的地面控制點布設(shè)在調(diào)整塊角落然后系統(tǒng)誤差補償各帶一組獨立的未知參數(shù)機載全球定位系統(tǒng)GPS的控制的平差最終的結(jié)果是購買廉價的機載的數(shù)據(jù)精度和GPS差分全球定位系統(tǒng)精度相同。雖然前者的精度比傳統(tǒng)束密集的地面控制點區(qū)域網(wǎng)平差低一點它仍然可以在許多尺度地形測繪滿足攝影點測定的精度要求。 關(guān)鍵詞形變監(jiān)

50、測滑坡GPS單歷元定位模糊度解算緒論 空中三角測量（AT）是用于分析天線的基本方法為了計算3維坐標的圖像對象點和影像的外方位元素。到現(xiàn)在為止已普遍采用平差A(yù)T和大量的地面控制點控制點是必要的調(diào)整計算。在20世紀50年代攝影測量開始利用其他輔助數(shù)據(jù)以減少控制點的數(shù)量。然而當時調(diào)查并沒有達到因為技術(shù)限制許多實施結(jié)果（李和山，1989） 在20世紀70年代隨著應(yīng)用全球定位系統(tǒng)（GPS）況發(fā)生了很大變化。GPS可提供測點的三維坐標厘米級精度在差分模式，因此它是適用于AT來衡量的空間位置坐標投影中心（以下簡稱來GPS相機站或作為機載GPS控制點）在這種方式控制點的數(shù)量可顯著降低。聯(lián)合平差攝影觀測和全球衛(wèi)

51、星定位系統(tǒng)確定位置透視中心被認為是作為GPS的支持。自從20世紀80年代開始，許多論文已提交的大量的研究和實驗結(jié)果的GPS支持（阿克曼，1984；弗里斯1986；盧卡斯，1987 ）。經(jīng)過約20年這些努力， GPS的支持，廣泛應(yīng)用于空中三角測量在許多尺度和所有類型的地形。這是特別有利的地方，他們是難以建立地面控制(阿克曼 1994)。 在20世紀90年代后期，隨著傳感器技術(shù)的發(fā)展，GPS 慣性導(dǎo)航系統(tǒng)( POS) 第一次使用在AT直接航拍圖像獲得的立體像對和地形的信息。在理論上,這種技術(shù)可以消除為控制點的需要。然而研究表明,數(shù)字正射影像圖可直接由地面點定位坐標;通過一臺POS(Cannon和s

52、un, 1996年獲得的參數(shù)等人2000年, Heipke等,2001 )但將有較大的垂直視差立體模型重建時使用這些圖像定向參數(shù)和高程精度不能滿足大比例尺地形圖測繪的要求。因此束塊應(yīng)作出調(diào)整合并后的圖像通過POS和攝影獲得的定向參數(shù)意見(Greening等2000) 。 是否利用POS機在AT 差分全球定位系統(tǒng)GPS數(shù)據(jù)或數(shù)據(jù)定位是提供必要的GPS相機站呈現(xiàn)。在差分全球定位系統(tǒng)模式下一個或多個GPS基準站應(yīng)布設(shè)在地面上,并同步觀察期間不斷連同機載GPS接收機整個飛行任務(wù)。此外,從GPS衛(wèi)星信號應(yīng)收到盡可能少的傳輸中斷。還需要之前飛機起飛和初始化測量著陸后靜態(tài)測量應(yīng)當執(zhí)行。 在處理GPS觀測載波相位差技術(shù)被用來消除或減少GPS定位誤差,包括衛(wèi)星時鐘誤差,衛(wèi)星軌道誤差,大氣延遲誤差等。一般來說它是很難放列正確的GPS參考站時航空攝影區(qū)域與大范圍或難以進行訪問和交流。為了航拍圖像以保證質(zhì)量,調(diào)查面積必須等很長一段時間拍攝,這是為了適合天氣來攝影。 GPS基準站因此很長一段時間留在原地。此外準確性還和DGPS定位基線長度有關(guān)。時間越長基線之間電離層的相關(guān)性較弱折射誤差,對流層延遲誤差越小。由于需要大氣延遲誤差,長度的空間相關(guān)性GPS差分基準通常限制在20公里內(nèi).如果厘米級精度要求高可靠性(星期日200