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The extraction of points on the bare earth from point clouds acquired by airborne laser scanning is one of the most important
steps for the generation of digital terrain models (DTM). This process is called “filtering”. However, most of the current
filters erode the bare earth in steep sloped landscapes and at discontinuities, and they retain low vegetation. Therefore,
a new filtering method for extracting ground points based on a distance limit is proposed in this paper. The angle criterion
is used to assure the robustness of the algorithm. The experimental results show that the proposed filtering method can effectively
derive the ground points from point clouds in complex urban areas.
Supported by the Program for Changjiang Scholars and Innovative Research Team in University (No.0438), the National 863 Program
of China (No. 2006AA12Z151). 相似文献
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LIDAR(Light Detection And Ranging)是近年来兴起的一种快速获取地物目标三维信息的主动遥感技术。LAS格式是测量与遥感(ASPRS)协会下属的LIDAR委员会制定的标准LIDAR数据格式,该格式是目前最常用的LIDAR数据存储格式,可以比较好地解决多属性离散激光点云数据的存储问题。具有结构严谨、便于扩展等优点。LAS格式先后有1.0,1.1,1.2,1.3四个版本。本文研究的内容是基于1.2版本,在对LAS格式进行解析的基础上,采用C++语言开发相应的读写功能,实现对数据的读取、修改、转换等常规处理。 相似文献
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结合LAS1.0,从公共文件头区、变长记录区和点集记录区3个方面,对LAS格式的各个版本进行了分析比较,并利用Matlab语言实现对各个版本LAS数据的读取、显示以及激光脚点的三维坐标、回波、强度等信息的提取,为后续LAS格式数据的处理奠定了基础。 相似文献
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LIDAR数据是目前生产DEM/DSM最为理想的数据源,利用机载激光雷达获取DEM/DSM数据是机载激光雷达最为直接的应用。本文提出了一种将LIDAR点云数据格网化与坡度滤波相结合的点云分类方法,该方法将数据格网化的概念用于LIDAR点云数据的预处理,避免了LIDAR点云数据内插或者平滑造成的信息损失,并且引入坡度突变对格网化处理后的LIDAR点云数据进行第二次地面点的选取,提高了LIDAR点云数据分类的效果。 相似文献
107.
The extraction of points on the bare earth from point clouds acquired by airborne laser scanning is one of the most important steps for the generation of digital terrain models (DTM). This process is called “filtering”. However, most of the current filters erode the bare earth in steep sloped landscapes and at discontinuities, and they retain low vegetation. Therefore, a new filtering method for extracting ground points based on a distance limit is proposed in this paper. The angle criterion is used to assure the robustness of the algorithm. The experimental results show that the proposed filtering method can effectively derive the ground points from point clouds in complex urban areas. 相似文献
108.
Jane Xinxin Zhang Kang‐Tsung Chang Joan Qiong Wu 《International journal of geographical information science》2013,27(8):925-942
Digital elevation models (DEMs) vary in resolution and accuracy by the production method. DEMs with different resolutions and accuracies can generate varied topographic and hydrological features, which can in turn affect predictions by soil erosion models, such as the WEPP (Water Erosion Prediction Project) model. This study investigates the effects of DEMs on deriving topographic and hydrological attributes, and on predicting watershed erosion using WEPP v2006.5. Six DEMs at three resolutions from three sources were prepared for two small forested watersheds located in northern Idaho, USA. These DEMs were used to calculate topographic and hydrological parameters that served as inputs to WEPP. The model results of sediment yields and runoffs were compared with field observations. For both watersheds, DEMs with different resolutions and sources generated varied watershed shapes and structures, which in turn led to different extracted hill slope and channel lengths and gradients, and produced substantially different erosion predictions by WEPP. 相似文献
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Batrice Morel Hassan Bencherif Philippe Keckhut Serge Baldy Alain Hauchecorne 《Journal of Atmospheric and Solar》2002,64(18)
Systematic measurements of the middle-atmosphere temperature by a RAYLEIGH LIDAR located at La Réunion Island (20.8°S–55.5°E) has led to a preliminary study of the tidal effects in the height range of 30–70 km. Two analysis methods able to estimate the mean nighttime evolution of the temperature have been compared. Method 1 consists in averaging the temperature deviations from the nightly mean over several successive nights of measurement for given local solar times (LST); method 2 consists in averaging the raw data over the period of observation for given LST and in deriving afterwards the mean nighttime evolution of the temperature profiles. Some consistent LST-related structures have been observed with both methods, though better results have been obtained with method 1. One possible explanation for the differences between the two methods is the use of a series of data ranging from 4 to 8 h/night, depending on the meteorological conditions. In contrast to method 2, method 1 allows to correct the mean temperature for a given night, when the measurement window is different from night to night. Method 1 has been applied to two time series recorded in October and November 1995. The results clearly show the presence of tidal components with a downward phase propagation, specifically a warmer early night and a colder midnight in the stratosphere and the lower mesosphere. This behaviour is consistent with other LIDAR measurements made at similar latitudes in the Northern Hemisphere. In addition, a close comparison with the Global-Scale Wave Model (GSWM) tidal model predictions has also pointed out some similarities. Yet, large discrepancies in magnitude are also observed: as already reported in previous studies, the amplitudes predicted by GSWM are more than two times smaller compared to the corresponding values observed with the LIDAR. 相似文献
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Assessment of long-range kinematic GPS positioning errors by comparison with airborne laser altimetry and satellite altimetry 总被引：3，自引：0，他引：3
Long-range airborne laser altimetry and laser scanning (LIDAR) or airborne gravity surveys in, for example, polar or oceanic
areas require airborne kinematic GPS baselines of many hundreds of kilometers in length. In such instances, with the complications
of ionospheric biases, it can be a real challenge for traditional differential kinematic GPS software to obtain reasonable
solutions. In this paper, we will describe attempts to validate an implementation of the precise point positioning (PPP) technique
on an aircraft without the use of a local GPS reference station. We will compare PPP solutions with other conventional GPS
solutions, as well as with independent data by comparison of airborne laser data with “ground truth” heights. The comparisons
involve two flights: A July 5, 2003, airborne laser flight line across the North Atlantic from Iceland to Scotland, and a
May 24, 2004, flight in an area of the Arctic Ocean north of Greenland, near-coincident in time and space with the ICESat
satellite laser altimeter. Both of these flights were more than 800 km long. Comparisons between different GPS methods and
four different software packages do not suggest a clear preference for any one, with the heights generally showing decimeter-level
agreement. For the comparison with the independent ICESat- and LIDAR-derived “ground truth” of ocean or sea-ice heights, the
statistics of comparison show a typical fit of around 10 cm RMS in the North Atlantic, and 30 cm in the sea-ice region north
of Greenland. Part of the latter 30 cm error is likely due to errors in the airborne LIDAR measurement and calibration, as
well as errors in the “ground truth” ocean surfaces due to drifting sea-ice. Nevertheless, the potential of the PPP method
for generating 10 cm level kinematic height positioning over long baselines is illustrated. 相似文献