A technique of digital surface model generation

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全球测图项目中基于不同软件进行DSM匹配结果的探究

10 m格网数字表面模型(DSM)是全球地理信息资源建设与维护更新(简称“全球测图”)项目中的一项产品,它是基于资源三号卫星立体影像及RPC参数,利用DSM生产软件,针对不同地形进行DSM匹配,进而进行DSM产品的生产。本文以全球测图项目为背景,探究利用Inpho7.0、PixelGrid6.0、CIPS 3种主流生产软件进行DSM匹配,探究不同软件在匹配精度、匹配效果和匹配效率方面的差别,得到不同软件在DSM生产中的使用原则,不仅为DSM产品的生产提供了技术支撑,也为全球测图项目的顺利推进提供借鉴和经验。     

房屋震害预测数字化辅助方法

为提高房屋震害预测效率,将数字化技术应用于房屋震害预测分类工作中。利用航空摄影测量、遥感及地理信息系统技术,提出两种房屋震害预测分类数字化辅助方法。若预测区域有符合条件的遥感影像对,利用航空摄影测量技术可获得DSM及DEM模型,进一步从层数上对建筑物进行分类。另一种方法则是利用遥感技术提取有关建筑物阴影信息,由阴影计算建筑物层数,进而对建筑物进行分类。利用地理信息系统自动统计不同类建筑物总面积,画出不同类建筑的地理分布图。与传统方法相比,这种方法效率高,可以纵览全局,减少房屋震害预测现场调查工作量,提高震害预测工作效率。     

Creating high-resolution bare-earth digital elevation models (DEMs) from stereo imagery in an area of densely vegetated deciduous forest using combinations of procedures designed for lidar point cloud filtering

For areas of the world that do not have access to lidar, fine-scale digital elevation models (DEMs) can be photogrammetrically created using globally available high-spatial resolution stereo satellite imagery. The resultant DEM is best termed a digital surface model (DSM) because it includes heights of surface features. In densely vegetated conditions, this inclusion can limit its usefulness in applications requiring a bare-earth DEM. This study explores the use of techniques designed for filtering lidar point clouds to mitigate the elevation artifacts caused by above ground features, within the context of a case study of Prince William Forest Park, Virginia, USA. The influences of land cover and leaf-on vs. leaf-off conditions are investigated, and the accuracy of the raw photogrammetric DSM extracted from leaf-on imagery was between that of a lidar bare-earth DEM and the Shuttle Radar Topography Mission DEM. Although the filtered leaf-on photogrammetric DEM retains some artifacts of the vegetation canopy and may not be useful for some applications, filtering procedures significantly improved the accuracy of the modeled terrain. The accuracy of the DSM extracted in leaf-off conditions was comparable in most areas to the lidar bare-earth DEM and filtering procedures resulted in accuracy comparable of that to the lidar DEM.     

无人机航空摄影测量系统在农村土地确权中的应用

介绍了用PPSG UAV对双鸭山市郊区2．5 km2地域（农村土地承包经营权确权双鸭山试点）试验区进行无人机航摄,无人机搭载非量测型相机获取低空遥感数据,计算机安装专业空三解算软件处理具体影像,最终取得数字正射影像图（ DOM）、数字表面模型（ DSM）,通过数据分析了该系统的空中三角测量成果的精度和数字正射影像图（ DOM）、数字表面模型（ DSM）的精度,都达到了航空摄影测量地理信息数字成果比例尺1∶1000的成图精度。     

遥感图像数字表面模型建筑物点过滤方法研究

针对图像密集匹配生产的数字表面模型(DSM)进行点云滤波,算法对地形依赖大,参数设置复杂,精度不高,后续人工编辑修饰的工作量大、效率低的问题,该文设计了第一套针对DSM滤波、涵盖多种样本形式(栅格、矢量)的航空图像建筑物数据集。针对航空图像建筑物尺度较大等特点,将膨胀卷积加入U-Net构成Dilated U-Net,并综合运用其进行建筑物语义分割,利用分割结果在相应图像密集匹配得到的DSM上滤除建筑物点,然后采用投票插值策略得到过滤掉建筑物点的DSM。实验证明:利用该文网络DU-Net将DSM中非地面建筑物点滤除,Ⅰ类误差在5.8%以内,Ⅱ类误差在2.4%以内,其可以在30 s内完成超过9000万个建筑点与非建筑物点位置的预测,效率高、成本低。DU-Net网络建筑物语义分割过程不受地形、高差的限制,对于其他非地面点的滤波具有一定的借鉴意义。     

基于资源三号卫星影像的无控大范围数字表面模型快速制作

作为重要的地理信息,数字表面模型具有非常广泛的应用前景,我国成功发射的资源三号卫星,不但填补了立体卫星测绘的空白,而且能够得到高分辨率的卫星遥感影像。本文基于资源三号卫星影像,简要介绍了无控大范围数字表面模型快速制作流程,并以此得到典型地区三维影像图,为数字表面模型在各行业的应用及发展提供重要支持。     

数字近景摄影测量在古建筑物重建中的应用研究

讨论了一种建立古建筑复杂表面构件的三维模型的方法.在工程作业现场,用数码相机 PC机 摄影测量软件 CAD的方法建立复杂构件的DSM.实践证明,这种方法是非常有效的.     

应用GeoStar建立数字佛像三维模型的研究

通过使用GeoStar系列软件进行数字三维佛像建模 ,进一步实现佛像的动态漫游 ,从而得出了一种基于等值线图建立数字表面模型并进行空间漫游的可行技术 ;通过研究卧佛的历史资料 ,对数字佛像模型进行修补 ,探讨了实现佛像表面三维可视化复原的方法     

利用GLAS激光测高数据评估DSM产品质量及精度优化

提出了一种利用卫星激光测高数据直接优化提升数字表面模型（DSM）产品精度的方法。选取境外中亚地区的资源三号DSM开展试验,通过采用多准则约束方法提取激光高程控制点,分别利用偏度、中值、线性、二次多项式等进行DSM误差修正,发现4种模型均能有效消除DSM系统误差,其中基于二次多项式的方法更适用于平地和丘陵地貌,线性模型更适用于高山地貌。试验验证了采用卫星激光测高数据优化境外DSM技术流程的可行性,最终可提高DSM的绝对高程精度。     

Effects of jpeg 2000 compression on automated dsm extraction: evidence from aerial photographs

This paper evaluates the effects of JPEG 2000 compression on automated digital surface model (DSM) extraction, using the area-based matching technique. Two stereopairs of aerial photographs, which have different photo scale, pixel size, and topographic type, are used as the images for the experiments. In the experiments, the DSM generated from the uncompressed image is set as the reference, and the elevation accuracy is computed for a range of compression ratios (2:1 to 100:1). The results show that the employed indices of image quality based on the JPEG 2000 compression are clearly superior to the commonly used JPEG compression technique—especially for high compression ratios. However, the elevation accuracy varies with the compression ratios. Also, JPEG 2000 compression does not have a significant influence on the percentage of the successful matching rate. In addition, a near linear fall-off is observed in extracted DSM accuracy with increasing compression ratios.     

无人机遥感真正射影像高精度制图

近年来无人机低空遥感技术不断发展,利用无人机影像生成的真正射影像（TDOM）在成图精度、制作流程方面仍有提高的空间。本文采用固定翼无人机和专业摄影相机采集影像,布设地面控制点,提出了利用运动恢复结构（SfM）和多视立体视觉（MVS）工作流来生成高精度数字表面模型（DSM）和数字正射影像（DOM）的方法;对遮蔽倾斜部分进行阴影检测、DSM修编和多视影像纹理补偿生成TDOM;最后用TDOM上随机分布的检查点进行精度检查,水平精度为3.3 cm,垂直精度为7.5 cm;消除了DOM中倾斜和阴影部分,使建筑物保持垂直视角,生成的满足1：500比例尺高精度并消除倾斜阴影的TDOM可用于农村宅基地确权、国土规划设计等领域。     

大比例尺数字测图质量控制方法探讨

大比例尺数字测图正以其测图精度高、成图速度快等优势逐步取代传统的以平板为主的模拟测图.与传统的模拟测图相比,数字测图的质量控制关键点更多、内容与方法更为复杂.结合厦门市西北部测区2003年大比例尺数字图测绘工程的实施情况,就如何在数字测图的各个环节实施质量控制,确保最终数字测绘产品成果(DLG)的数据质量,进行探讨.     

基于GPGPU技术快速提取数字表面模型

介绍一种基于通用计算图形处理单元（GPGPU）技术快速提取数字表面模型（DSM）的方法,探讨了使用LiDAR和摄影测量方法获取数字表面模型的不同特点,并通过分别使用CPU和GPU技术获取一个大面积山区数字表面模型的案例对比,证明了基于CUDA架构的数字表面模型提取方法是有效和可行的。     

Change detection of buildings using an airborne laser scanner

This study employed an airborne laser scanner to detect changes of buildings by acquiring a digital surface model (DSM) data of urban areas. Simple comparison between DSM data sets acquired at different occasions successfully detected building changes without omission errors. A CCD array image simultaneously acquired with the DSM data was also automatically orthorectified with the DSM data and indicated to help revise the building database efficiently.     

利用投影影像精化数字表面模型

随着摄影测量技术的成熟和人们对摄影测量产品应用的要求不断提高,真正射影像在工程与人们生活中扮演越来越重要的角色。生成高质量真正射影像的关键在于如何获取高精度的DSM。目前修正和改善DSM误差的方法普遍存在费力费时、精度缺乏保证及任意性等问题。本文针对DSM精度的修正问题提出了一种新的方法,即基于投影影像的概念,将空间点位在投影影像上的投影轨迹线作为几何约束条件,直接对现有DSM的高程进行修正的方法。通过获取高精度的DSM,进而生成更为精确的真正射影像。本文通过理论推导、单点高程和多点高程修正试验,验证了提出的新方法直观简单,适用性强,具有一定的实际应用价值。     

一种综合利用像方和物方信息的多影像匹配方法(英文)

A novel method for multi-image matching by synthesizing image and object-space information is proposed. Firstly, four levels of image pyramids are generated according to the rule that the next pyramid level is generated from the previous level using the average gray values of the 3 by 3 pixels, and the first level of pyramid image is generated from the original image. The initial horizontal parallaxes between the reference image and each searching image are calculated at the highest level of the image pyramid. Secondly, corresponding image points are searched in each stereo image pair from the third level of image pyramid, and the matching results in all stereo pairs are integrated in the object space, by which the mismatched image points can be eliminated and more accurate spatial information can be obtained for the subsequent pyramid image matching. The matching method based on correlation coefficient with geometric constraints and global relaxation matching is introduced in the process of image matching. Finally, the feasibility of the method proposed in this paper is verified by the experiments using a set of digital frame aerial images with big overlap. Compared with the traditional image matching method with two images, the accuracy of the digital surface model (DSM) generated using the proposed method shows that the multi-image matching method can eliminate the mismatched points effectively and can improve the matching success rate significantly. Supported by the National Natural Science Foundation of China (Nos. 40771176, 40721001).     

Updating digital elevation models via change detection and fusion of human and remote sensor data in urban environments

OpenStreetMap (OSM) currently represents the most popular project of Volunteered Geographic Information (VGI): geodata are collected by common people and made available for public use. Airborne Laser Scanning (ALS) enables the acquisition of high-resolution digital elevation models that are used for many applications. This study combines the advantages of both ALS and OSM, offering a promising new approach that enhances data quality and allows change detection: the mainly up-to-date 2D data of OSM can be combined with the high-resolution – but rarely updated – elevation information provided by ALS. This case study investigates building objects of OSM and ALS data of the city of Bregenz, Austria. Data quality of OSM is discerned by the comparison of building footprints using different true positive definitions (e.g. overlapping area). High quality of OSM data is revealed, yet also limitations of each method with respect to heterogeneous regions and building outlines are identified. For the first time, an up-to-date Digital Surface Model (DSM) combining 2D OSM and ALS data is achieved. A multitude of applications such as flood simulations and solar potential assessments can directly benefit from this data combination, since their value and reliability strongly depend on an up-to-date DSM.     

电子平板测图软件EPSW在地籍测绘中的应用

当前计算机技术在测绘领域中的应用正迅速发展,在测图方面,传统的白纸测图因为手工在图纸上按一定比例尺绘制一菜,地物要素导致作业效率低下和原始数量数据精度受损。数字测图是以数字的形式表达地物特征点的全解析机助测图方法,它具有作业效率高,成图规范,原始测量数据精度无损伯的优点。     

2-D delineation of individual citrus trees from UAV-based dense photogrammetric surface models

One of the challenges of remote sensing and computer vision lies in the three-dimensional (3-D) reconstruction of individual trees by using automated methods through very high-resolution (VHR) data sets. However, a successful and complete 3-D reconstruction relies on precise delineation of the trees in two dimensions. In this paper, we present an original approach to detect and delineate citrus trees using unmanned aerial vehicles based on photogrammetric digital surface models (DSMs). The symmetry of the citrus trees in a DSM is handled by an orientation-based radial symmetry transform which is computed in a unique way. Next, we propose an efficient strategy to accurately build influence regions of each tree, and then we delineate individual citrus trees through active contours by taking into account the influence region of each canopy. We also present two efficient strategies to filter out erroneously detected canopy regions without having any height thresholds. Experiments are carried out on eight test DSMs composed of different types of citrus orchards with varying densities and canopy sizes. Extensive comparisons to the state-of-the-art approaches reveal that our proposed approach provides superior detection and delineation performances through supporting a nice balance between precision and recall measures.