Metadata for Flathead Basin, Montana, High Resolution Orthophotos and Elevation Data, 2009 Metadata for Flathead Basin, Montana, High Resolution Orthophotos and Elevation Data, 2009

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Citation:

Originator: Watershed Sciences
Originator: 3Di West (GeoTerra Mapping Group)
Publication date: 11/16/2010
Title:: Flathead Basin, Montana, High Resolution Orthophotos and Elevation Data, 2009
Online linkage: https://msl.mt.gov/geoinfo/data/flathead_basin_mapping_project_-_2009/

Abstract:

This data collection includes natural color and color-infrared orthorectified aerial photos whose horizontal resolution is one foot, digital elevation models whose resolutions are 3 feet and 6 feet, 2-foot topographic contour lines, and LiDAR .las point files.

The data were collected between September 22 and September 29, 2009, and they cover the floor of the Flathead Valley above Flathead Lake, the area around Polson, and the shoreline areas of Flathead Lake, Whitefish Lake, and Swan Lake. All of the data are in Montana State Plane Coordinates, NAD83 HARN, and the horizontal and vertical units are U.S. Survey Feet. The vertical datum of the data is NAVD88, Geoid 03.

The web site, https://msl.mt.gov/geoinfo/data/flathead_basin_mapping_project_-_2009/, provides access to the entire data set, but it is generally only practical for downloading small portions of the 150-gigabyte data set. Instructions for obtaining the data via surface mail on portable media are at http://geoinfo.msl.mt.gov/Home/data/flathead_basin_mapping_project_-_2009/data_delivery.

The downloadable color air photos and color infrared air photos are in zip files that each hold approximately six MrSID images that each cover approximately 700 acres. There are 780 images in each (color and IR) collection. Each collection is also available as a group of 8 large (400-750Mb each) MrSID image mosaics.

The Digital Elevation Models are available as two collections of 106 TIFF files. One collection consists of 3-foot DEMs developed from the LiDAR ground returns, and the other is made up of 6-foot DEMs that were developed from the LiDAR data in conjunction with photogrammetric breaklines used to create a hydrologically-correct surface. The breakline data are also available on the web site.

The 2-foot contour line data are available in two formats. One is a collection of 106 ESRI file geodatabases provided by the contractor, in which many of the contour lines have multiple vertices per linear foot of ground distance. The other is a collection of 106 ESRI shapefiles that have had the vertex density greately reduced by being generalized from the geodatabase vectors with a horizontal tolerance of 1.5 inches.

There are two sets of LiDAR .las files. Each consists of 2150 files, each covering about 170 acres, that have been placed in 330 zip files for download. One set of files contains all of the data points for ground, vegetation, and structures, while the other set contains only the data points from the ground. The "all return" data contain approximately 5 points per square meter and the "ground return" data contain approximately 1.5 points per square meter.

Time period of content:

Beginning date: 09/22/2009
Ending date: 09/29/2009
Currentness reference: ground condition

Access constraints: none

Use constraints:

The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time.

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