Maui_2019_DTM

Digital Terrain Model (bare earth) of parts of Maui and Molokai. Partial coverage Vexcel, Inc. LIDAR of Maui and Molokai were purchased by County of Maui to assist with three-dimensional modeling of structures in areas of higher development. 1'/px, LIDAR-derived, bare earth DEM/elevation raster of parts of Maui and Molokai – specifically, Central Molokai, Kahului, Kihei, Lahaina and Pukalani. XY units: feet, Z units: meters. Use Limitations: 1.Disclaimer - This dataset is being placed in the public domain. Any use is allowed except for re-sale. Neither Vexcel, Inc., the County of Maui, nor the State of Hawaii make any guarantees, expressed or implied, regarding its accuracy or fitness of use. Users should verify XYZ values through a licensed surveyor for any engineering application. This data should only be used as a guide, vs. a statement of fact regarding real-world conditions. 2.Vertical Datum - The originator of this LIDAR dataset, Vexcel Inc. of Boulder, Colorado referenced Z values to the North American Vertical Datum of 1988 (NAVD88). NAVD88 is not recognized as a valid vertical reference for the state of Hawaii. Currently Hawaii has no official (de jure or de facto) vertical datum, and NOAA's National Geodetic Survey (NGS) recommends that elevations be referenced to the nearest NOAA tidal gauge. A legacy LIDAR dataset produced in 2013 by the United States Army Corps of Engineers (USACE) used NAD83(PA11) as its vertical reference. In theory this approach should result in better accuracy for the Z dimension as PA11 is a Pacific plate-centric datum. In comparing flat areas containing neither structures or vegetation, it was found that the Vexcel values sit approximately 4 feet above the USACE dataset. The vertical datum issue was brought to the attention of Vexcel, Inc. Vexcel used the 2013 USACE LIDAR as vertical control to correct their LIDAR data. The (corrected) .las data is shared as it was delivered. As stated above, the use of this data transfers all risks and assumption of responsibility to the user. For more information see https://files.hawaii.gov/dbedt/op/gis/data/Maui_2019_DTM.html or contact County of Maui at [e-mail] or Hawaii Statewide GIS Program at [e-mail].茂宜岛（Maui）与莫洛凯岛（Molokai）部分区域的裸地数字地面模型（Digital Terrain Model）。茂宜郡（County of Maui）采购了部分覆盖茂宜岛与莫洛凯岛的伟克斯公司（Vexcel, Inc.）激光雷达（Light Detection and Ranging, LIDAR）数据，用于辅助开展高开发强度区域的建筑三维建模工作。本数据分辨率为1英尺每像素，为基于激光雷达获取的裸地数字高程模型（Digital Elevation Model, DEM）/高程栅格数据，覆盖茂宜岛与莫洛凯岛的部分区域，具体包括莫洛凯岛中部、卡胡卢伊（Kahului）、基黑（Kihei）、拉海纳（Lahaina）和普卡拉尼（Pukalani）。X、Y坐标单位为英尺，Z坐标单位为米。 使用限制： 1. 免责声明——本数据集已进入公共领域，除转售外，任何使用方式均不受限制。伟克斯公司（Vexcel, Inc.）、茂宜郡及夏威夷州均不对本数据集的准确性或适用性作出任何明示或默示担保。若将本数据用于工程类应用，用户需通过持证测量师对X、Y、Z坐标值进行核验。本数据仅可作为参考依据，不得作为现实世界地形状况的事实性表述。 2. 垂直基准面——本激光雷达数据集的制作方，科罗拉多州博尔德市的伟克斯公司（Vexcel, Inc.），将Z值参照1988年北美垂直基准面（North American Vertical Datum of 1988, NAVD88）进行计算。夏威夷州并不认可NAVD88作为合法的垂直参考基准。目前夏威夷州尚无官方（法定或事实上）的垂直基准面，美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）下属的国家大地测量局（National Geodetic Survey, NGS）建议将高程参照最近的NOAA潮位站数据。 2013年由美国陆军工程兵团（United States Army Corps of Engineers, USACE）制作的老旧激光雷达数据集，以NAD83(PA11)作为垂直参考基准。由于PA11是以太平洋板块为中心的基准面，理论上该基准下的Z轴坐标精度更高。通过对无建筑与植被的平坦区域进行比对，发现伟克斯公司数据集的Z值较美国陆军工程兵团数据集高出约4英尺。针对垂直基准面的问题，伟克斯公司已获悉相关情况，并采用2013年美国陆军工程兵团的激光雷达数据作为垂直控制基准，对自身激光雷达数据进行了校正。本数据集共享的（已校正）.las格式数据按照交付时的状态发布。如前所述，使用本数据的全部风险与责任均由用户自行承担。如需获取更多信息，请访问https://files.hawaii.gov/dbedt/op/gis/data/Maui_2019_DTM.html，或联系茂宜郡（邮箱：[e-mail]）或夏威夷全州地理信息系统项目（邮箱：[e-mail]）。