Kakadu LIDAR Project 2011 - LiDAR_Point_Clouds, UNClassified. ELL

LiDAR_Point_Clouds, UNClassified. ELL Files swaths of flight collected data. Points are located by Elevation, Latitude and Longitude. The file formats is LAS. \n\nLAS is an industry format created and maintained by the American Society for Photogrammetry and Remote Sensing (ASPRS). LAS is a published standard file format for the interchange of lidar data. It maintains specific information related to lidar data. It is a way for vendors and clients to interchange data and maintain all information specific to that data.\nEach LAS file contains metadata of the lidar survey in a header block followed by individual records for each laser pulse recorded. The header portion of each LAS file holds attribute information on the lidar survey itself: data extents, flight date, flight time, number of point records, number of points by return, any applied data offset, and any applied scale factor. The following lidar point attributes are maintained for each laser pulse of a LAS file: x,y,z location information, GPS time stamp, intensity, return number, number of returns, point classification values, scan angle, additional RGB values, scan direction, edge of flight line, user data, point source ID and waveform information.\nEach and every lidar point in a LAS file can have a classification code set for it. Classifying lidar data allows you to organize mass points into specific data classes while still maintaining them as a whole data collection in LAS files. Typically, these classification codes represent the type of object that has reflected the laser pulse. Point classification is usually completed by data vendors using semi-automated techniques on the point cloud to assign the feature type associated with each point. Lidar points can be classified into a number of categories including bare earth or ground, top of canopy, and water. The different classes are defined using numeric integer codes in the LAS files. The following table contains the LAS classification codes as defined in the LAS 1.1 standard:\nClass code Classification type\n0 Never classified\n1 Unassigned\n2 Ground\n3 Low vegetation\n4 Medium vegetation\n5 High vegetation\n6 Building\n7 Noise\n8 Model key\n9 Water\n\n\nLineage: LIDAR Survey of the floodplains within Kakadu National Park conducted by Fugro Spatial Solutions for Geoscience Australia \nFugro Spatial Solutions were awarded a contract by Geoscience Australia to carry out an Aerial LiDAR Survey over the Kakadu. The data will be used to examine the potential impacts of climate change and sea level rise on the West Alligator, South Alligator, East Alligator River systems and other minor areas.\nThe project area was flight planned using parameters as specified. A FSS aircraft and aircrew were mobilised to site and the project area was captured using a Leica ALS60 system positioned using a DGPS base-station at Darwin airport. The Darwin base-station was positioned by DGPS observations from local control stations. A ground control survey was carried out by FSS surveyors to determine ground positions and heights for control and check points throughout the area. All data was returned to FSS office in Perth and processed. The deliverable datasets were generated and supplied to Geoscience Australia with this metadata information.\n\nNEDF Metadata\n Acquisition Start Date: Saturday, 22 October 2011\n Acquisition End Date: Wednesday, 16 November 2011\n Sensor: LiDAR\n Device Name: Leica ALS60 (S/N: 6145)\n Flying Height (AGL): 1409\n INS/IMU Used: uIRS-56024477\n Number of Runs: 468\n Number of Cross Runs: 28\n Swath Width: 997\n Flight Direction: Non-Cardinal\n Swath (side) Overlap: 20\n Horizontal Datum: GDA94\n Vertical Datum: AHD71\n Map Projection: MGA53\n Description of Aerotriangulation Process Used: Not Applicable\n Description of Rectification Process Used: Not Applicable\n Spatial Accuracy Horizontal: 0.8\n Spatial Accuracy Vertical: 0.3\n Average Point Spacing (per/sqm): 2\n Laser Return Types: 4 pulses (1st 2nd 3rd 4th and intensity)\n Data Thinning: None\n Laser Footprint Size: 0.32\n Calibration certification (Manufacturer/Cert. Company): Leica\n Limitations of the Data: To project specification\n Surface Type: Various\n Product Type: Other\n Classification Type: C0\n Grid Resolution: 2\n Distribution Format: Other\n Processing/Derivation Lineage: Capture, Geodetic Validation\n WMS: Not Applicable?\n\n

未分类激光雷达（LiDAR）点云数据集，数据为飞行条带采集所得的ELL格式文件，点云坐标通过高程、纬度与经度确定，文件格式为LAS。

LAS是由美国摄影测量与遥感学会（American Society for Photogrammetry and Remote Sensing, ASPRS）制定并维护的行业标准格式，亦是激光雷达数据交换的公开标准文件格式。该格式可存储激光雷达数据的专属信息，为供应商与客户提供数据交换并完整保留该数据所有专属信息的途径。

每个LAS文件均包含激光雷达测量的元数据，存储于文件头区块中，后续为每条记录的实测激光脉冲数据。每个LAS文件的文件头部分存储激光雷达测量本身的属性信息：数据范围、飞行日期、飞行时长、点记录总数、按回波数分类的点数量、已应用的数据偏移量与比例因子。LAS文件中为每个激光脉冲存储以下激光雷达点属性：x、y、z位置信息、GPS时间戳、强度值、回波序号、总回波数、点分类码、扫描角、附加RGB值、扫描方向、飞行线边缘标记、用户数据、点源ID与波形信息。

LAS文件中的每个激光雷达点均可配置分类码。对激光雷达数据进行分类，可将海量点云组织为特定数据类别，同时仍可将其作为完整的LAS数据集保留。此类分类码通常代表反射激光脉冲的物体类型。点分类工作通常由数据供应商通过半自动化技术对点云进行处理，为每个点分配对应的要素类型。激光雷达点可划分为多个类别，包括裸地/地面、冠层顶部与水体等。LAS文件中通过数值型整数代码定义不同类别。下表为LAS 1.1标准中定义的LAS分类码：
分类码 分类类型
0 未分类
1 未分配
2 地面
3 低矮植被
4 中等植被
5 高大植被
6 建筑物
7 噪声点
8 模型关键点
9 水体

数据溯源：由Fugro空间解决方案公司（Fugro Spatial Solutions）为澳大利亚地球科学局（Geoscience Australia）开展的卡卡杜国家公园泛滥平原激光雷达测量项目。
Fugro空间解决方案公司获澳大利亚地球科学局委托，开展卡卡杜地区的航空激光雷达测量工作，该数据集将用于评估气候变化与海平面上升对西鳄鱼河、南鳄鱼河、东鳄鱼河水系及其他小型区域的潜在影响。
项目作业区域按照既定参数进行飞行规划，调动FSS的飞机与机组人员前往作业现场，使用搭载于达尔文机场DGPS基准站的Leica ALS60系统完成数据采集。达尔文基准站通过本地控制站的DGPS观测进行定位。FSS测量人员开展地面控制测量，以确定作业区域内控制点与检查点的地面位置及高程。所有数据被传回珀斯的FSS办公室进行处理，最终生成可交付数据集并随本元数据一同交付给澳大利亚地球科学局。

NEDF元数据
采集开始日期：2011年10月22日，星期六
采集结束日期：2011年11月16日，星期三
传感器：激光雷达
设备名称：Leica ALS60（序列号：6145）
飞行高度（AGL）：1409
搭载的INS/IMU：uIRS-56024477
飞行趟数：468
交叉飞行趟数：28
条带宽度：997
飞行方向：非主方位
条带（侧向）重叠度：20
水平基准面：GDA94
垂直基准面：AHD71
地图投影：MGA53
航空三角测量过程说明：不适用
纠正过程说明：不适用
空间水平精度：0.8
空间垂直精度：0.3
平均点间距（每平方米）：2
激光回波类型：4个回波（第1、2、3、4回波及强度值）
数据精简：无
激光光斑尺寸：0.32
校准认证（制造商/认证机构）：Leica
数据局限性：符合项目规范
地表类型：多种
产品类型：其他
分类类型：C0
网格分辨率：2
分发格式：其他
处理/衍生溯源：采集、大地测量验证
WMS：不适用？