利用基元分解的机载点云复杂建筑物自动重建

针对复杂建筑物自动重建中重建类型有限和边界线确定困难的问题,提出了一种基于基元分解的机载点云建筑物重建方法。该方法通过对屋顶面构建拓扑图并依据最小环原则进行拓扑分解,将复杂建筑物分解成多个简单基元;根据拓扑图的基本要素建立一个涵盖常见基元的建筑基元库,通过将复杂建筑物分解得到的基元与建筑基元库中的基元进行匹配,将复杂建筑物的重建转化为简单基元的重建,解决复杂建筑物重建类型有限的问题;综合利用建筑物整体外轮廓和屋脊线来确定基元边界线,克服数据缺失等因素对边界精度的影响。实验结果表明,该方法可有效地对多种复杂建筑物进行自动重建,具有可靠的精度。     

基于机载激光雷达数据的简单规则建筑物模型重建

机载激光雷达数据具有直接描述对象几何特征、便于表达空间不连续变化等优势,是建筑物重建的主要数据源之一。为实现基于激光雷达点云数据的模型自动重建和解决现有方法存在的问题,提出了一种基于特征线提取、面向简单规则建筑物的重建方法。该方法以投影为基础,以平高分解为手段,通过在多个投影平面内逐步确定平面、高程信息实现特征线提取及模型重建。实验表明,该方法能够避免现有方法遇到的若干困难,有效重建简单规则建筑物模型。     

基于图像识别的建筑物三维重建

为从彩色高分辨率的图像中提取出主要建筑物的位置信息并进行三维重建,提出一种结合2D和3-D信息识别建筑物,通过纹理集技术进行大规模3-D重建的方法.进行边缘检测,提取可用的短直线以及相应的2-D特征,对这些短直线进行逐级聚类得到候选屋顶集合;通过朴素贝叶斯分类器在候选屋顶集合中区分出不同的3D屋顶特征,以识别全局优秀的屋顶;根据屋顶的位置信息,在大规模的3-D场景中绘制出相应尺寸的模型,通过动态分配算法将建筑物纹理合并,减少纹理数量,从而减少纹理状态的切换.以航拍和卫星遥感彩色高分辨率图像进行实验,实验结果表明,该方法有优秀的识别正确率和3-D重建效果.     

三维建筑模型的规则化重构方法

基于无人机照片的倾斜摄影测量技术能够快速重建大量三维建筑模型;但这些模型数据量大、噪声多,极大阻碍了在智慧城市中的应用.针对倾斜摄影测量重建的三维建筑模型屋顶重建精度较高的特点,提出一种基于屋顶轮廓线的三维建筑模型规则化重构方法.首先分割屋顶并提取屋顶的外轮廓线;接着通过改进的平面拟合提取屋顶的内轮廓线;然后由屋顶内外轮廓线进一步拟合出屋顶平面几何基元;最后,针对屋顶中太阳能、烟囱等的非平面部分,进行补充规则化处理,重构出数据小、噪声少的三维建筑模型.本文方法能够将三维建筑模型自动地重构为规则的建筑体,不依赖用户交互和先验信息.大量实验证明了本文方法的有效性、高效性和鲁棒性.     

LIDAR点云中多层屋顶轮廓线提取方法研究

在分析LIDAR数据提取建筑物轮廓线现状的基础上,针对多层、非规则屋顶轮廓线提取的难点,提出一种直接基于离散点云的屋顶轮廓线提取方法,该方法主要包括屋顶点的识别,初始轮廓线的提取以及轮廓线的规则化等步骤。最后采用实地数据进行验证,结果表明该方法具有一定的应用前景。     

一种高分辨率遥感图像中居民区道路提取方法

针对在遥感图像中提取居民区道路易受房屋等人工建筑干扰的问题,基于数学形态学提出了一种可以去除大量建筑物干扰,从而有效提取出居民区道路的算法.算法首先用顶帽变换和底帽变换对灰度图像进行了对比度争强,然后利用道路和建筑物之间的形态梯度以及道路特征对道路和建筑物进行分离,最后利用形态重建的方法得到了居民区道路网.仿真实验表明,区域中的大部分建筑物噪声被成功去除,算法是有效和可行的.     

SAR图像建筑物成像特性及重建研究方法

基于SAR图像中平面屋顶建筑物的成像机理,介绍SAR图像中建筑物的信息获取和重建方法,包括成像特性、建筑物平面长条屋顶的提取、建筑物高度计算.通过成像原理,利用建筑物二次散射亮线及叠掩、阴影区域定位建筑物屋顶区域,再结合叠掩、阴影区域反推出建筑物高度的计算公式,实现建筑物三维重建.     

基于深层卷积残差网络的航拍图建筑物精确分割方法

针对建筑物3D建模场景下所需的建筑物主体轮廓俯视平面图获取成本较高、航拍图建筑物的分割精度低、建筑物屋顶存在干扰物影响分割等问题,文中提出了一种将5个点的位置表示为热图作为网络额外输入通道的基于深层残差网络的航拍图建筑物精确分割方法,该方法在航拍图建筑物的精确分割任务中取得了比较好的分割效果。实验结果表明,该方法具有比传统半自动分割方法Grabcut更高的分割精度和分割效率;具有比DEXTR方法更好的鲁棒性和抗干扰性。该方法可以为建筑物3D重建任务提供高精度的建筑物俯视轮廓图和建筑物顶部图片,还可以在航拍图建筑物数据集的制作过程中,作为一种准确和有效的掩码注释工具或半自动轮廓标注工具,以提高数据集的标注效率。     

基于建筑物提取的精细尺度人口估算研究

以精细尺度的人口估算为目标,提出一种根据居民区建筑物属性估算人口数量的方法。首先基于Dempster-Shafer证据理论,结合LiDAR数据和高分辨率遥感影像进行建筑物的自动提取。根据土地利用分类图排除提取结果中的非居民区建筑后,按照线性回归的思想,通过对居民建筑物的数量、面积、体积等几何属性的优化选择建立人口估算模型。实验表明,利用该估算模型能够获得较高精度的小面积目标区域上的估算结果。该方法提高了人口估算的精细程度和自动化程度。     

建筑物三维场景重建方法

针对建筑物模型的规则性问题,基于一幅或多幅非标定图像,对建筑物结构进行多视角三维场景重建,得到360°观测模型。区别于传统三维重建方法,该方法无需先标定摄像机参数与逐点配准、不依赖深度数据和高分辨率图像。实验结果表明该方法解决了单张图像方向性感知视野受限的问题,在系统复杂度和速度上优于传统方法。     

Complete residential urban area reconstruction from dense aerial LiDAR point clouds

We present an automatic system to reconstruct 3D urban models for residential areas from aerial LiDAR scans. The key difference between downtown area modeling and residential area modeling is that the latter usually contains rich vegetation. Thus, we propose a robust classification algorithm that effectively classifies LiDAR points into trees, buildings, and ground. The classification algorithm adopts an energy minimization scheme based on the 2.5D characteristic of building structures: buildings are composed of opaque skyward roof surfaces and vertical walls, making the interior of building structures invisible to laser scans; in contrast, trees do not possess such characteristic and thus point samples can exist underneath tree crowns. Once the point cloud is successfully classified, our system reconstructs buildings and trees respectively, resulting in a hybrid model representing the 3D urban reality of residential areas.     

Managing heat rejected from air conditioning systems to save energy and improve the microclimates of residential buildings

Simulations are conducted to investigate the influence and improvement potential of air conditioning heat rejection management of residential buildings on microclimate and energy use. The microclimate and building energy use are simulated on a typical high-rise building in Taipei, Taiwan, on a summer night. Heat rejection from the air conditioners is estimated with a building energy program, EnergyPlus, and a computational fluid dynamics (CFD) program, Windperfect, is used to analyze how heat rejection affects the outside thermal environment. Results show that heat rejection from air conditioners worsens the thermal environment below the urban canopy, thus increasing building energy use. Three countermeasure cases of heat rejection management, which consider the type of cooling system and its installation position, are proposed in this study. The average air temperature increase around the buildings caused by heat rejection was analyzed by transferring the simulation results of the building energy program to the CFD model on an hourly basis. Results show that the air temperature next to the building envelope and the air temperature around air conditioners decrease and that there is a reduction in electricity consumption by the air conditioners when a split-type air conditioner is installed on each floor or on every third floor. A reduction in the ambient air temperature below the urban canopy can be obtained by placing a cooling tower on the roof of the building.     

基于知识发现的TM图像居民地自动提取研究

快速准确获取不同类型居民地的空间分布信息具有极其重要的意义,居民地的分布具有点多,面广的特点,这使得地面调查的方法费工费时,遥感技术的发展为居民地的获取提供了先进的技术手段,但是目前从遥感图像中提取居民地的方法多为目视判读提取,这种方法难以满足诸如灾害评估等方面的实时要求。为此以居民地背景较好的成都平原为例,通过对该区1988年的TM图像 不同类型居民地及其背景的光谱特征进行分析,发现了该区两大主要居民地类垢光谱特征知识,这两大类型分别为以水泥顶或瓦顶房屋为主的居民地,主要为城镇一级以上的居民地,另一类为以草顶为主的集村居民地,。由于城镇一级的居民地,其光谱特征与河滩地比较接近,为此又进一步引进了居民地与水体和道路的空间关系知识,利用所发现的知识分别建立了城镇居民地的提取模型和集村居民地的提取模型,实例研究表明,在民民地背景比较好的平原地区,利用这两种模型不仅可以实现自动提取以水泥顶或瓦顶房屋为主的居民地,而且还能够提取以草顶房屋为主的居民地,其精度可以达到85％。     

从机载激光扫描数据中交互式提取人字形房屋模型的方法研究

快速有效地从机载激光扫描(airborne lidar)点云数据中提取房屋模型是机载激光扫描系统应用研究的一项重要课题。鉴于交互式半自动方法是从点云数据中提取简单规则房屋模型信息的一种可行的方法,为此采用3维空间中改进的Hough变换以及聚类分析,提出了一种从点云数据中交互式提取人字形房屋模型的方法。该方法分为3个步骤:第1步是用户确定房屋区域,并分割出候选的屋顶点集;第2步是对候选屋顶点集采用3维空间中改进的Hough变换,然后对Hough变换后所获得的参数集进行聚类分析,以此获得屋顶所在平面的参数表达;第3步是构造完整的房屋模型。通过屋顶平面相交得到屋脊线,通过点的范围分析确定屋顶的边缘,最后添加竖直的墙面构造完整的房屋模型。经采用Optech公司提供的数据进行实验初步证实,该方法是可行的,且整个提取过程只需要很少的用户交互,因此适合于大规模处理机载激光扫描数据。     

Detecting damaged building parts in earthquake-damaged areas using differential seeded region growing

Acquiring information about earthquake-damaged buildings is essential for effective rescue and restoration operations. Building damage must be assessed to provide detailed information regarding the location and proportion of damage to individual buildings. Automatic processing of damage assessment is also critical in hastening relief efforts. Therefore, we propose a new method for automatically extracting damaged building parts and quantitatively assessing the damage to individual buildings caused by earthquakes. The proposed method consists of four parts: generating differential information, differential seeded region growing (DSRG), rule-based earthquake damage analysis, and accuracy assessment. First, differential information is automatically derived to extract the damage candidates. The damage candidates are then used as seed points for the region growing process to extract damaged building parts without requiring intervention by a human analyst. Then, designed automated extraction rules based on the condition of the collapsed or crushed buildings are used on the DSRG results. We applied the proposed method to both a residential area and a business area in Port-au-Prince, Haiti, and evaluated its accuracy using a visual comparison, a location-based assessment, and a proportion-based assessment. The results of the visual comparison were similar to the reference data, exhibiting location accuracies of 86% and 89% for the chosen residential and business areas, respectively. An assessment of the damage proportion to individual buildings was performed, which showed that the proposed method achieved accuracies of 81% and 84% for the residential and business areas, respectively, and was highly correlated with the reference data. The proposed method can accurately estimate damaged building parts, which can accelerate rapid relief actions in earthquake-damaged areas. In addition, the proposed method promotes cost-effective relief actions because it filters out many intact buildings without omitting damaged buildings.     

3D city models for urban farming site identification in buildings

Studies have suggested that there is farming potential in urban residential buildings. However, these studies are limited in scope, require field visits and time-consuming measurements. Furthermore, they have not suggested ways to identify suitable sites on a larger scale let alone means of surveying numerous micro-locations across the same building. Using a case study area focused on high-rise buildings in Singapore, this paper examines a novel application of three-dimensional (3D) city models to identify suitable farming micro-locations (level and orientation) in residential buildings. We specifically investigate whether the vertical spaces of these buildings comprising outdoor corridors, façades and windows receive sufficient photosynthetically active radiation (PAR) for growing food crops and do so at a high resolution. We also analyze the spatio-temporal characteristics of PAR, and the impact of shadows and different weather conditions on PAR in the building. Environmental simulations on the 3D model of the study area indicated that the cumulative daily PAR or Daily Light Integral (DLI) at a location in the building was dependent on its orientation and shape, sun's diurnal and annual motion, weather conditions, and shadowing effects of the building's own façades and surrounding buildings. The DLI in the study area generally increased with building's levels and, depending on the particular micro-location, was found suitable for growing moderately light-demanding crops such as lettuce and sweet pepper. These variations in DLI at different locations of the same building affirmed the need for such simulations. The simulations were validated with field measurements of PAR, and correlation coefficients between them exceeded 0.5 in most cases thus, making a case that 3D city models offer a promising practical solution to identifying suitable farming locations in residential buildings, and have the potential for urban-scale applications.     

基于视差的高分辨率遥感影像建筑物变化检测

针对城区高分辨率遥感影像建筑物变化检测中视差引起误检测问题，提出一种基于视差的建筑物变化检测方法。首先，利用改进的双峰分裂法实现对建筑物阴影的检测；然后，借助阴影估计屋顶的位置，并自动选取种子区域，结合区域生长法进行建筑屋顶提取；最后，以视差、视差方位角以及面积等作为判定条件对两时相影像建筑物的变化情况进行分析。通过对WorldView-2影像和IKONOS影像进行变化检测，平均正确率达到了89.6%。实验结果表明:在屋顶光谱均匀且有明显建筑阴影的稀疏建筑区，该方法能够有效解决建筑屋顶种子区域自动选取及高层建筑视差引起误检测等难点问题。     

基于视差的高分辨率遥感影像建筑物变化检测

针对城区高分辨率遥感影像建筑物变化检测中视差引起误检测问题,提出一种基于视差的建筑物变化检测方法。首先,利用改进的双峰分裂法实现对建筑物阴影的检测;然后,借助阴影估计屋顶的位置,并自动选取种子区域,结合区域生长法进行建筑屋顶提取;最后,以视差、视差方位角以及面积等作为判定条件对两时相影像建筑物的变化情况进行分析。通过对WorldView-2影像和IKONOS影像进行变化检测,平均正确率达到了89.6%。实验结果表明:在屋顶光谱均匀且有明显建筑阴影的稀疏建筑区,该方法能够有效解决建筑屋顶种子区域自动选取及高层建筑视差引起误检测等难点问题。     

Assessing Vertical Greenery Distribution and Spatial Allocation based on Multi-source Remote Sensing：A Case Study of Székesfehérvár City，Hungary#br#

Taking as Székesfehérvár,Hungary a case study,vertical greenery distribution and spatial allocation is studied.Based on the multi\|source remote sensing data,three-dimensional information of urban green space and buildings is extracted.A height sampling method is used to quantify the vertical distribution of green space and building space.According to the spatial allocation relationship,the vertical space is divided into “Green\|deficient layer” and “Green\|sufficient layer”,and the vertical spatial allocation characteristics of different function zonings are compared and analyzed.Case study findings indicate that：(1) greenery vertical structure of residential area and commercial area are similar,but residential area has greater allocation quantity; (2) the first to third building floors in commercial area are considered green-deficient due to the shortage of green space allocation and its monotonous vertical structure,and there is inadequate green space provision for high\|rise building floors in residential area; (3) the major cause for low\|rise green deprivation in commercial area is the high density of low\|rise building structure,and neglecting skyrise greenery results in the high\|rise green deprivation in residential area. 