Digital Surface Model (DSM) from 2005 LiDAR for the Green Lakes Valley, Colorado

This 1m Digital Surface Model (DSM) is derived from first-stop Light Detection and
Ranging (LiDAR) point cloud data from September 2005 for the Green Lakes Valley,
near Boulder Colorado. The DSM was created from LiDAR point cloud tiles subsampled
to 1-meter postings, acquired by the National Center for Airborne Laser Mapping
(NCALM) project. This data was collected in collaboration between the University of
Colorado, Institute of Arctic and Alpine Research (INSTAAR) and NCALM, which is
funded by the National Science Foundation (NSF). The DSM has the functionality of a
map layer for use in Geographic Information Systems (GIS) or remote sensing
software. Total area imaged is 35 km^2. The LiDAR point cloud data was acquired with
an Optech 1233 Airborne Laser Terrain Mapper (ALTM) and mounted in a twin engine
Piper Chieftain (N931SA) with Inertial Measurement Unit (IMU) at a flying height of
600 m. Data from two GPS (Global Positioning System) ground stations were used for
aircraft trajectory determination. The continuous DSM surface was created by
mosaicing and then kriging 1 km2 LiDAR point cloud LAS-formated tiles using Golden
Software's Surfer 8 Kriging algorithm. Horizontal accuracy and vertical accuracy is
unknown. cm RMSE at 1 sigma. The layer is available in GEOTIF format approx. 265 MB
of data. It has a UTM zone 13 projection, with a NAD83 horizonal datum and a NAVD88
vertical datum computed using NGS GEOID03 model, with FGDC-compliant metadata. A
shaded relief model was also generated. A similar layer, the Digital Terrain Model
(DTM), is a ground-surface elevation dataset better suited for derived layers such
as slope angle, aspect, and contours. A processing report and readme file are
included with this data release. The DSM is available through an unrestricted public
license. The LiDAR DEMs will be of interest to land managers, scientists, and others
for study of topography, ecosystems, and environmental change. NOTE: This EML
metadata file does not contain important geospatial data processing information.
Before using any NWT LTER geospatial data read the arcgis metadata XML file in
either ISO or FGDC compliant format, using ArcGIS software (ArcCatalog >
description), or by viewing the .xml file provided with the geospatial dataset.

本1米分辨率数字地表模型（Digital Surface Model, DSM）源自2005年9月采集于科罗拉多州博尔德附近绿湖谷的首次激光雷达（Light Detection and Ranging, LiDAR）点云数据。该DSM由美国国家机载激光测绘中心（National Center for Airborne Laser Mapping, NCALM）项目获取的LiDAR点云瓦片经降采样至1米点位后生成。本数据由科罗拉多大学北极与高山研究所（Institute of Arctic and Alpine Research, INSTAAR）与NCALM合作采集，NCALM由美国国家科学基金会（National Science Foundation, NSF）资助。该DSM可作为地图图层应用于地理信息系统（Geographic Information Systems, GIS）或遥感软件中，成像总面积达35平方千米。本次LiDAR点云数据采用Optech 1233型机载激光地形测绘仪（Airborne Laser Terrain Mapper, ALTM）采集，搭载于配备惯性测量单元（Inertial Measurement Unit, IMU）的双引擎Piper Chieftain（N931SA）飞机，飞行高度为600米。采用两座GPS（全球定位系统, Global Positioning System）地面站的数据解算飞机飞行轨迹。通过镶嵌并应用Golden Software公司的Surfer 8克里金算法，对1平方千米的LAS格式LiDAR点云瓦片进行插值处理，生成连续的DSM表面。水平精度与垂直精度尚未明确，1σ置信水平下的均方根误差（RMSE）单位为厘米。该图层以GEOTIF格式提供，数据量约265MB。其投影为UTM第13带，水平基准面为NAD83，垂直基准面为采用美国国家大地测量局（NGS）GEOID03模型计算的NAVD88，且附带符合联邦地理数据委员会（Federal Geographic Data Committee, FGDC）规范的元数据。此外还生成了阴影地形模型。与之类似的数字地形模型（Digital Terrain Model, DTM）为地表高程数据集，更适用于生成坡度、坡向、等高线等派生图层。本次数据发布附带处理报告与说明文件。该DSM采用无限制公共授权协议发布。此类LiDAR数字高程模型（DEM）可用于地形、生态系统与环境变化研究，适用于土地管理者、科研人员等群体。注意：本EML元数据文件未包含重要的地理空间数据处理信息。在使用任何NWT LTER地理空间数据前，请使用ArcGIS软件（ArcCatalog > 描述）查看符合ISO或FGDC标准的ArcGIS元数据XML文件，或直接查阅随地理空间数据集附带的.xml文件。