利用高精度DLG进行机载LiDAR点云精度评定研究
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摘要
LiDAR作为一种主动式获取高精度地表几何信息的地形图测绘技术,其获取的点云具有较高的相对精度与绝对精度,可作为无控或稀少控制条件下(无人机)航空影像高精度几何定位的地理参考数据。影像几何定位所能达到的精度依赖于几何参考数据自身的精度,因此评价LiDAR点云的精度对于将其作为地理参考实现航空影像高精度几何定位,具有较强的理论价值与实践意义。本文提出了利用高精度数字线划图(DLG)作为几何参考评定机载LiDAR点云精度的方法。首先,通过比对DLG中高程注记点的高程与LiDAR点云中对应位置处的高程,实现LiDAR点云高程精度评定;然后,通过统计LiDAR墙面点在平面上的投影点到DLG房屋矢量轮廓线的距离,实现LiDAR点云平面精度评定。实验结果证明,本文试验区域LiDAR点云平面和高程精度分别可达到7.2 cm和8.3 cm,可作为大比例尺无人机航空遥感控制数据的有效选择。
LiDAR is an active topographic mapping technique for obtaining high precision surface geometric information. In recent years, LiDAR point cloud has been widely used and gradually become a new standard geospatial information product, because of its efficiency, directness and easy availability. Due to its high accuracy, LiDAR point cloud data can be used as georeference data for aerial triangulation of unmanned aerial vehicle(UAV) imagery with sparse ground control points(GCPs) or even without GCP. Because the accuracy of aerial triangulation strongly depends on the accuracy of georeference data itself, so it is of great practical significance to evaluate the accuracy of LiDAR point cloud as georeference data. In this study, we proposed a method for evaluating the accuracy of airborne LiDAR point cloud data using high precision digital line graphic(DLG) as reference data. This method realizes not only the assessment of the vertical accuracy of LiDAR point cloud, but also the reliable assessment of the horizontal accuracy of LiDAR point cloud. Firstly, the vertical accuracy was evaluated by comparing the elevations of the elevation points in DLG with the elevations of the LiDAR points at corresponding positions. Secondly, the facade points of LiDAR buildings were extracted and projected into a horizontal plane, and their distances from the outlines of buildings in DLG were calculated to evaluate the horizontal accuracy of LiDAR point cloud. Due to the existence of a large number of elevation points and building contours in the DLG, the accuracy assessment samples were abundant, and the assessment results could reflect the true accuracy level of LiDAR point cloud. The experiments showed that the horizontal and vertical accuracy of LiDAR point cloud in the test area could reach 7.2 cm and 8.3 cm, respectively, which proved that LiDAR can be used as an effective control data for large scale UAV aerial remote sensing purpose.
LiDAR is an active topographic mapping technique for obtaining high precision surface geometric information. In recent years, LiDAR point cloud has been widely used and gradually become a new standard geospatial information product, because of its efficiency, directness and easy availability. Due to its high accuracy, LiDAR point cloud data can be used as georeference data for aerial triangulation of unmanned aerial vehicle(UAV) imagery with sparse ground control points(GCPs) or even without GCP. Because the accuracy of aerial triangulation strongly depends on the accuracy of georeference data itself, so it is of great practical significance to evaluate the accuracy of LiDAR point cloud as georeference data. In this study, we proposed a method for evaluating the accuracy of airborne LiDAR point cloud data using high precision digital line graphic(DLG) as reference data. This method realizes not only the assessment of the vertical accuracy of LiDAR point cloud, but also the reliable assessment of the horizontal accuracy of LiDAR point cloud. Firstly, the vertical accuracy was evaluated by comparing the elevations of the elevation points in DLG with the elevations of the LiDAR points at corresponding positions. Secondly, the facade points of LiDAR buildings were extracted and projected into a horizontal plane, and their distances from the outlines of buildings in DLG were calculated to evaluate the horizontal accuracy of LiDAR point cloud. Due to the existence of a large number of elevation points and building contours in the DLG, the accuracy assessment samples were abundant, and the assessment results could reflect the true accuracy level of LiDAR point cloud. The experiments showed that the horizontal and vertical accuracy of LiDAR point cloud in the test area could reach 7.2 cm and 8.3 cm, respectively, which proved that LiDAR can be used as an effective control data for large scale UAV aerial remote sensing purpose.
引文
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[15]赵礼剑,程新文,李英成,等.机载LIDAR点云高程数据精度检核及误差来源分析[J].地理空间信息,2009,7(1):58-60.[Zhao L J,Cheng X W,Li Y C,et al.Accuracy check and analysis of LiDAR elevation data[J].Geospatial Information,2009,7(1):58-60.]
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[18]Reutebuch S E,Mcgaughey R J,Andersen H E,et al.Accuracy of a high-resolution LiDAR terrain model under a conifer forest canopy[J].Canadian Journal of Remote Sensing,2003,29(5):527-535.
[19]Hodgson M E,Bresnahan P.Accuracy of airborne LiDAR-derived elevation:Empirical assessment and Error Budget[J].Photogrammetric Engineering&Remote Sensing,2004,70(3):331-339.
[20]Csanyi N,Toth C K.Improvement of Lidar data accuracy using Lidar-specific ground targets[J].Photogrammetric Engineering&Remote Sensing,2007,73(4):385-396.
[21]马洪超,张良,高广,等.一种检查机载LiDAR平面精度的新方法[J].测绘通报,2014(7):14-17.[Ma H C,Zhang L,Gao G,et al.A new method for airborne LiDAR plane precision evaluation.Bulletin of Surveying and Mapping,2014(7):14-17.]
[22]邢吉昌,施昆,李志杰.国产机载LiDAR平面精度检查新方法[J].浙江农业科学,2017,58(2):326-329.[Xing J X,Shi K,Li Z J,A new method for domestic airborne LiDAR plane precision evaluation[J].Journal of Zhejiang Agricultural Sciences,2017,58(2):326-329.]
[23]Ray J A,Graham L.New horizontal accuracy assessment tools and techniques for Li DAR data[C].Proceedings of the ASPRS Annual Conference,Portland/Oregon,USA,2008.
[24]宋孟肖.LiDAR点云辅助的城区航空影像空中三角测量[D].武汉:武汉大学,2018.[Song M X.LiDAR point cloud assisted aerotriangulation of urban airborne image[D].Wuhan:Wuhan University,2018.]
[2]廖小罕,周成虎,苏奋振,等.无人机遥感众创时代[J].地球信息科学学报,2016,18(11):1439-1447.[Liao X H,Zhou C H,Su F Z,et al.The mass innovation era of UAVremote sensing[J].Journal of Geo-information Science,2016,18(11):1439-1447.]
[3]张祖勋,陶鹏杰.谈大数据时代的“云控制”摄影测量[J].测绘学报,2017,46(10):1238-1248.[Zhang Z X,Tao P J.An overview on"cloud control"photogrammetry in big data era[J].Acta Geodaetica et Cartographica Sinica,2017,46(10):1238-1248.]
[4]Tao P J,Lu L P,Zhang Y,et al.On-orbit geometric calibration of the panchromatic/multispectral camera of the ZY-102C satellite based on public geographic data[J].Photogrammetric Engineering&Remote Sensing,2014,80(6):505-517.
[5]Zhuo X,Koch T,Kurz F,et al.Automatic UAV image geo-registration by matching UAV images to georeferenced image data[J].Remote Sensing,2017,9(4):376.
[6]Zhang Z X,Lu L P,Tao P J,et al.Registration of CBERS-02B satellite imagery in quick GIS updating[C].In MIP-PR 2011:Remote Sensing Image Processing,Geographic Information Systems,and Other Applications,80060C,23 November,Guilin,2011.
[7]Shan J,Toth C K.Topographic Laser Ranging and Scanning:Principles and Processing[M]//Scanning-Principles and Processing;CRS Press:Boca,2008:215-234.
[8]National lidar dataset[EB/OL].[2018-09-01]https://en.wikipedia.org/wiki/National_lidar_dataset.
[9]Zhang Y J,Xiong X D,Zheng M T,et al.LiDAR strip adjustment using multifeatures matched with aerial images[J].IEEE Transaction on Geoscience and Remote Sensing,2014,53(2):976-87.
[10]Wang L,Song W,Liu Z,et al.Airborne Li DAR strip adjustment based on LSM[C].Proceedings of the International Congress on Image and Signal Processing,2010(6):2727-31.
[11]Wu J.Airborne LiDAR data strip adjustment based on least squares matching and independent model[C].Proceedings of the International Conference on Multimedia Technology,2010:1-4.
[12]Csanyi N,Toth C K.Point positioning accuracy of airborne LiDAR systems:A rigorous analysis[C].International Archives of Photogrammetry,Remote Sensing and Spatial Information Sciences 2007.
[13]Schaer P,Skaloud J,Landtwing S,et al.Accuracy estimation for laser point cloud including scanning geometry[C].Mobile Mapping Symposium,Padova,2007.
[14]陈刚,田玉刚,程新文,等.山区LiDAR高程精度野外检验的一种新方法[J].测绘通报,2008(2):41-43.[Chen G,Tian Y G,Cheng X W,et al.A new method for field LiDAR elevation precision testing in mountainous areas[J].Bulletin of Surveying and Mapping,2008(2):41-43.]
[15]赵礼剑,程新文,李英成,等.机载LIDAR点云高程数据精度检核及误差来源分析[J].地理空间信息,2009,7(1):58-60.[Zhao L J,Cheng X W,Li Y C,et al.Accuracy check and analysis of LiDAR elevation data[J].Geospatial Information,2009,7(1):58-60.]
[16]Dharmapuri S S.Vertical accuracy validation of LiDARdata[J].LiDAR Magazine,2014,4(2):1.
[17]Pourali S,Arrowsmith C,Chrisman N,et al.Vertical accuracy assessment of LiDAR ground points using minimum distance approach[C].Proceedings Research@Locate,Canberra,Australia,2014.
[18]Reutebuch S E,Mcgaughey R J,Andersen H E,et al.Accuracy of a high-resolution LiDAR terrain model under a conifer forest canopy[J].Canadian Journal of Remote Sensing,2003,29(5):527-535.
[19]Hodgson M E,Bresnahan P.Accuracy of airborne LiDAR-derived elevation:Empirical assessment and Error Budget[J].Photogrammetric Engineering&Remote Sensing,2004,70(3):331-339.
[20]Csanyi N,Toth C K.Improvement of Lidar data accuracy using Lidar-specific ground targets[J].Photogrammetric Engineering&Remote Sensing,2007,73(4):385-396.
[21]马洪超,张良,高广,等.一种检查机载LiDAR平面精度的新方法[J].测绘通报,2014(7):14-17.[Ma H C,Zhang L,Gao G,et al.A new method for airborne LiDAR plane precision evaluation.Bulletin of Surveying and Mapping,2014(7):14-17.]
[22]邢吉昌,施昆,李志杰.国产机载LiDAR平面精度检查新方法[J].浙江农业科学,2017,58(2):326-329.[Xing J X,Shi K,Li Z J,A new method for domestic airborne LiDAR plane precision evaluation[J].Journal of Zhejiang Agricultural Sciences,2017,58(2):326-329.]
[23]Ray J A,Graham L.New horizontal accuracy assessment tools and techniques for Li DAR data[C].Proceedings of the ASPRS Annual Conference,Portland/Oregon,USA,2008.
[24]宋孟肖.LiDAR点云辅助的城区航空影像空中三角测量[D].武汉:武汉大学,2018.[Song M X.LiDAR point cloud assisted aerotriangulation of urban airborne image[D].Wuhan:Wuhan University,2018.]