High-Resolution Orthorectified Imagery from 1946, Niwot Ridge LTER Project Area, Colorado

Citation: Manley, W.F.,
Parrish, E.G., and Lestak, L.R., 2009, High-Resolution Orthorectified
Imagery and Digital Elevation Models for Study of Environmental Change at
Niwot Ridge and Green Lakes Valley, Colorado: Niwot Ridge LTER, INSTAAR,
University of Colorado at Boulder, digital media. This image is a mosaic of orthorectified aerial photography from 1946 for the
Niwot Ridge Long Term Ecological Research (LTER) project area at 0.3 m resolution.
The image also covers the Green Lakes Valley portion of the Boulder Creek Critical
Zone Observatory (CZO). The 1938 companion mosaic covers the eastern portion of the
Niwot LTER project area and was produced with maximum overlap of the 1946 mosaic.
The mosaic has the qualities of a photograph and the functionality of a map layer
for use in Geographic Information Systems (GIS) or remote sensing software. The
mosaic is derived from approx. 1:20,000 scale, black and white (grayscale)
photographs acquired by the United States Forest Service (USFS). The aerial photos
were obtained as 1800 dpi digital scans from the Colorado Aerial Photo Service and
then fully orthorectified in a Leica Photogrammetry Suite (LPS) bundle blockfile
using an air-photo camera model, a Digital Elevation Model (DEM), known focal
length, and hand-measured fiducial coordinates. Individual photo frames were
mosaiced with cutlines, then adjusted with additional geocorrection in ArcMap using
a 2nd order polynomial warp, and clipped to the Niwot project extent area. The
photography was registered to 2008 orthocorrected Denver Region Council of
Governments (DRCOG) aerial photography. Horizontal accuracy is 1.8 m (RMSE, relative
to the 2008 reference imagery, based on 6 independent check points). The mosaic
covers an area of 63 km2 and is available in GeoTIFF format, in a UTM zone 13
projection and NAD83 horizontal datum, with FGDC-compliant metadata. The mosaic is
available through an unrestricted public license, and can be obtained by request
(see Distributor contact information below). Other datasets available in this series
includes orthorectified aerial photograph mosaics (for 1938, 1953, 1972, 1985, 1990,
1999, 2002, 2004, 2005, 2006 and 2008), digital elevation models (DEM's), and
accessory map layers. Together, the DEM's and imagery will be of interest to
students, research scientists, and others for observation and analysis of natural
features and ecosystems. 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.