High-Resolution Orthorectified Imagery from 1938, 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 1938 for the
Niwot Ridge Long Term Ecological Research (LTER) project area at 0.3 m resolution.
The 1946 companion mosaic covers the western portion of the Niwot LTER and Green
Lakes Valley portion of the Boulder Creek Critical Zone Observatory (CZO) project
area and was produced with maximum overlap of the 1938 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 a non-metric camera
model, estimated focal length, calculated flying height and no fiducials. Individual
photo frames were mosaiced with cutlines, then adjusted with additional
geocorrection in ArcMap using a 3rd 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 7.0
m (RMSE, relative to the 2008 reference imagery, based on 4 independent check
points). The mosaic covers an area of 55 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 1946, 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.