DRAPP02 Orthophotography from 2002, Niwot Ridge LTER Project Area, Colorado

An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation has been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map. For this dataset, 1-foot nominal pixel resolution natural color aerial photography was contracted by USGS for the greater Denver metropolitan area with supplemental areas of interest added by the Denver Regional Council of Governments (DRCOG). Digital orthimages were obtained through a cooperative agreement between the USGS and DRCOG. Orthoimages were created by contrator in the state plane coordinate system for DRCOG. Reprojection to Universal Transverse Mercator (UTM) projection was done by contractor for USGS. The USGS resampled UTM orthoimages to a 0.3-meter pixel resolution 1500 X 1500-meter ground coverage footprint. There is no image overlap between adjacent files. The naming convention is based on the U.S. National Grid (USNG), taking the coordinates of the SW corner of the orthoimage. 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.正射影像（orthoimage）是一类通过数学手段消除了地形起伏与传感器姿态所引发的影像特征位移的遥感影像数据。正射影像兼具照片的影像表现力与地图的几何精度特性。本数据集采用标称1英尺像素分辨率的自然色彩航空摄影数据，由美国地质调查局（USGS）为丹佛大都市区采购，丹佛区域政府理事会（DRCOG）补充了部分额外的感兴趣区域。数字正射影像通过美国地质调查局与丹佛区域政府理事会的合作协议获取。正射影像最初由承包商基于丹佛区域政府理事会的州平面坐标系生成，随后承包商应美国地质调查局要求，将其重投影为通用横轴墨卡托投影（Universal Transverse Mercator, UTM）坐标系。美国地质调查局将UTM格式的正射影像重采样至0.3米的像素分辨率，单幅影像的地面覆盖范围为1500×1500米。相邻影像文件之间不存在重叠区域。数据集的命名规则基于美国国家网格（U.S. National Grid, USNG），以正射影像西南角的坐标作为命名依据。注意：本EML元数据文件未包含关键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，请通过ArcGIS软件（ArcGIS目录>描述信息）读取符合ISO或FGDC标准的ArcGIS元数据XML文件，或直接查看随地理空间数据集一同提供的.xml文件。