Metadata for Flathead Basin 6-foot Hydrologically Corrected Digital Elevation Models

Identification Information
Data Quality Information
Spatial Reference Information
Distribution Information
Metadata Reference Information

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Identification Information:

Citation:

Originator: Montana Department of Natural Resources and Conservation
Originator: Watershed Sciences, Inc.
Publication date: 11/16/2010
Title:: Flathead Basin 6-foot Hydrologically Corrected Digital Elevation Models
Online linkage: http://geoinfo.montanastatelibrary.org/data/flatheadbasin_mapping_project_2009/digital_elevation_model_data/6-foot_digital_elevation_models/

Abstract:

The dataset lies within Flathead and Lake Counties in northwestern Montana.
The bare earth digital elevation model (DEM) represents the earth's surface with all vegetation and human-made structures removed. The bare earth DEM was derived from LiDAR data using TIN processing of the ground point returns. This DEM was then enhanced using photogrammetric breaklines. The DEM grid cell size is 6 feet. The elevation units are in feet. Some elevation values have been interpolated across areas in the ground model where there is no elevation data (e.g. over water, over dense vegetation).

Watershed Sciences, Inc. collected the LiDAR and created this data set for the Montana Department of Natural Resources and Conservation

Purpose:

Provide high resolution terrain elevation and land cover elevation data with the hydrography enhanced using photogrammetric breaklines

Time period of content:

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

Status:

Progress: Complete
Maintenance and update frequency: None planned

Access constraints: None

Use constraints:

In some areas of heavy vegetation or forest cover, there may be relatively few ground points in the LiDAR data. TINing the points produces large triangles and hence the elevations may be less accurate within such areas.

Elevation values for open water surfaces are not valid elevation values because few LiDAR points are returned from water surfaces. Triangles were created across water surfaces by interpolating from the nearest land points.

The Montana State Library Geographic Information Services 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.

Point of contact:

Stephen Story
Montana Department of Natural Resources and Conservation
PO Box 201601
1424 9th Ave.
Helena, MT 59620-1601
Telephone: 406-444-6664
E-Mail: sestory@mt.gov

Data set credit: Montana Department of Natural Resources and Conservation

Data Quality Information:

Logical consistency report:

LiDAR flight lines have been examined to ensure that there was at least 50% sidelap, there are no gaps between flightlines, and overlapping flightlines have consistent elevation values.

Shaded relief images have been visually inspected for data errors such as pits, border artifacts, gaps, and shifting. The data was examined at a 1:2000 scale.

Quantitative horizontal positional accuracy assessment:

Horizontal positional accuracy explanation:: See LiDAR data report -- http://docs.msl.mt.gov/geoinfo/Flathead_2009/Reports/Documents/RemoteSensingReport.pdf

Quantitative vertical positional accuracy assessment:

Vertical positional accuracy value: RMSE = 0.118 feet (0.036 meters)
Vertical positional accuracy explanation:: The Root Mean Square Error (RMSE) of the data set is 0.118 feet (0.036 meters). Accuracy was assessed using 4229 ground survey (real time kinematic) points. Please see LiDAR data report for a discussion of statistics related to these datasets.

Lineage:

Process step:: Acquisition.

The LiDAR data was collected from September 22nd - 29th, 2009. The survey used a Leica ALS50 Phase II laser system mounted in a Cessna Caravan 208. Near nadir scan angles were used to increase penetration of vegetation to ground surfaces. Ground level GPS and aircraft IMU were collected during the flight.
Process step:: Processing.

1. Flight lines and data were reviewed to ensure complete coverage of the study area and positional accuracy of the laser points.
2. Laser point return coordinates were computed using ALS Post Processor software, IPAS Pro GPS/INS software, and Waypoint GPS, based on independent data from the LiDAR system, IMU, and aircraft.
3. The raw LiDAR file was assembled into flight lines per return with each point having an associated x, y, and z coordinate.
4. Visual inspection of swath to swath laser point consistencies within the study area were used to perform manual refinements of system alignment.
5. Custom algorithms were designed to evaluate points between adjacent flight lines. Automated system alignment was computed based upon randomly selected swath to swath accuracy measurements that consider elevation, slope, and intensities. Specifically, refinement in the combination of system pitch, roll and yaw offset parameters optimize internal consistency.
6. Noise (e.g., pits and birds) was filtered using ALS postprocessing software, based on known elevation ranges and included the removal of any cycle slips.
7. Using TerraScan and Microstation, ground classifications utilized custom settings appropriate to the study area.
8. The corrected and filtered return points were compared to the RTK ground survey points collected to verify the vertical and horizontal accuracies.
9. Points were output as laser points, and TINed
10. Hard breaklines were incorporated into the TIN by enforcing triangle edges (adjacent to the breakline) to the elevation values derived from the photogrammetric breakline.
11. The resulting TIN was converted into an ESRI grid with a 6 foot pixel resolution.
12. ArcHydro was run on ground models to inspect stream definition. In areas where stream definition deviated from bare earth ground model and breaklines, LiDAR data was reexamined to provide increased detail.

Spatial Reference Information:

Horizontal coordinate system definition:

Grid coordinate system name: State Plane Coordinate System

SPCS zone identifier: 2500

Lambert conformal conic:

Standard parallel: 45.000000
Standard parallel: 49.000000
Longitude of central meridian: -109.500000
Latitude of projection origin: 44.250000
False easting: 600000.000000
False northing: 0.000000

Planar distance units: U.S. Survey Feet

Geodetic model:

Horizontal datum name: D_North_American_1983_HARN
Ellipsoid name: Geodetic Reference System 80
Semi-major axis: 6378137.000000
Denominator of flattening ratio: 298.257222

Altitude system definition:

Altitude datum name: North American Vertical Datum of 1988 Geoid 3
Altitude distance units: U.S. Survey Feet

Distribution Information:

Distributor:

Montana State Library
PO Box 201800
Helena, MT 59620-1800
Telephone: 406-444-5354
E-Mail: geoinfo@mt.gov

Resource description: Downloadable Data

Distribution liability:

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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Format name: TIFF
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Metadata Reference Information:

Metadata date: 10/31/2013

Metadata review date: 12/03/2010

Metadata contact:

Watershed Sciences, Inc.
257 B SW Madison Ave
Corvallis, OR 97333
Telephone: 541-752-1204
E-Mail: watershedsciences.com