High-resolution lidar data for Alaska infrastructure corridors

Metadata also available as - [Parseable text] - [XML]

Frequently-anticipated questions:

What does this data set describe?

Title: High-resolution lidar data for Alaska infrastructure corridors
Abstract:
In advance of design, permitting, and construction of a pipeline to deliver North Slope natural gas to out-of-state customers and Alaska communities, the Division of Geological & Geophysical Surveys (DGGS) has acquired lidar (Light Detection and Ranging) data along proposed pipeline routes, nearby areas of infrastructure, and regions where significant geologic hazards have been identified. Lidar data will serve multiple purposes, but have primarily been collected to (1) evaluate active faulting, slope instability, thaw settlement, erosion, and other engineering constraints along proposed pipeline routes, and (2) provide a base layer for the state-federal GIS database that will be used to evaluate permit applications and construction plans. This shapefile contains kinematicly-corrected trajectory data presented as a 1Hz sampling of the original 200 Hz Smooth-Best estimate Trajectory files (SBET).
Supplemental_Information:
This metadata file has been written to document and describe the SBET data generated for this project. Information about accuracy and quality of lidar data can be found in quality control reports provided by DOGAMI and delivery reports provided by Watershed Sciences, Inc. Individual reports were provided for each delivery set and have been combined by DGGS into comprehensive quality control and delivery reports. These documents are organized according to how data were delivered to DGGS. A description of information pertaining to the downloadable files can be found in the quality control and delivery reports. The DGGS metadata standard extends the FGDC standard to also include several elements that are required to facilitate our internal data management. These elements, referred to as "layers," group and describe files that have intrinsic logical or topological relationships. This dataset describes a single layer titled: 
sbet:  Smoothed Best Estimate Trajectory shapefile
  1. How should this data set be cited?

    Hubbard, T.D., Koehler, R.D., and Combellick, R.A., 2011, High-resolution lidar data for Alaska infrastructure corridors: Raw Data File RDF 2011-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 291 p.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -150.82
    East_Bounding_Coordinate: -141.00
    North_Bounding_Coordinate: 70.38
    South_Bounding_Coordinate: 61.04

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 2010
    Ending_Date: 2011
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data, document

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a point data set.

    2. What coordinate system is used to represent geographic features?

      The map projection used is Alaska Albers Equal Area Conic.

      Projection parameters:
      Standard_Parallel: 55
      Standard_Parallel: 65
      Longitude_of_Central_Meridian: -154
      Latitude_of_Projection_Origin: 50
      False_Easting: 0
      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000001
      Ordinates (y-coordinates) are specified to the nearest 0.000001
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    rdf2011-3-sbet
    Kinematicly-corrected trajectory data presented as a 1Hz sampling of the original 200 Hz Smooth-Best estimate Trajectory files (SBET). (Source: this report)

    GPS_Time
    GPS_Time (s) of data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:56.50408
    Maximum:604792.57899

    Height
    Height (m) of plane during data collection: NAVD88 Geoid 09 (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:18.837
    Maximum:5159.32

    Roll
    Roll (deg) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:-41.478219
    Maximum:38.613914

    Pitch
    Pitch (deg) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:-33.227986
    Maximum:22.134247

    Heading
    Heading (deg) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:-179.999985
    Maximum:179.999816

    E_vel
    Easting velocity (m/s) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:-97.92675781
    Maximum:94.57273102

    N_vel
    Northing velocity (m/s) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:-91.3674469
    Maximum:111.9095993

    H_vel
    Height velocity (m/s) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:-20.27645302
    Maximum:23.23749542

    Std_E
    Standard deviation around Easting (m) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:0.003
    Maximum:0.036

    Std_N
    Standard deviation around Northing (m) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:0.003
    Maximum:0.032

    Std_H
    Standard deviation around Height (m) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:0.005
    Maximum:0.047

    Std_Roll
    Standard deviation around Roll (arcSec) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:2.2
    Maximum:17.8

    Std_Pitch
    Standard deviation around Pitch (arcSec) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:2.2
    Maximum:20.1

    Std_Head
    Standard deviation around Heading (arcSec) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:3.5
    Maximum:158.8

    Std_E_vel
    Standard deviation around Easting velocity (m/s) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:0.001
    Maximum:0.006

    Std_N_vel
    Standard deviation around Northing Velocity (m/s) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:0.001
    Maximum:0.008

    Std_H_vel
    Standard deviation around Height Velocity (m/s) of the plane during data collection (Source: Watershed Sciences, Inc.)

    Range of values
    Minimum:0.001
    Maximum:0.006

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Data collection was supported by funding from the Department of Natural Resources (DNR), Division of Geological & Geophysical Surveys (DGGS), the Alaska Gas Pipeline Project Office, the Office of the Federal Coordinator, and the Alaska Gasline Development Corporation (AGDC). Lidar data were collected and processed by Watershed Sciences, Inc. of Corvallis, OR. Survey data were collected by McClintock Land Associates of Eagle River, AK. Lidar data and derivative products were checked for quality, completeness, and accuracy by State of Oregon Department of Geology & Mineral Industries based in Portland, OR.

  3. To whom should users address questions about the data?

    Alaska Division of Geological & Geophysical Surveys
    c/o James Weakland
    GIS Analyst
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907)451-5029 (voice)
    dggsgis@alaska.gov

Why was the data set created?

Provide aircraft position and attitude during acquisition of lidar data.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 2010 (process 1 of 3)
    Acquisition: The lidar data were collected between September and October 2010 and between May and July 2011.The survey used the Leica ALS60 system. Ground-level GPS and aircraft IMU were collected during the flight. The following settings were used: Survey altitude (AGL) = 900 meters, Mirror scan rate = 55 Hz, Pulse rate = 105 kHz, Single pulse mode, Field of view (FOV) = 28 degree (+/- 8 degrees from nadir), 60% side lap (>100% overlap), Laser swath width = 448 meters, Airspeed = 105 knots per hour, Footprint = 24 cm. On each collection date, there was no cloud cover below 5000 feet and no precipitation. Flight-line specifics are provided in the attribute tables of the SBET shapefiles. Ancillary equipment includes: Trimble R7 receivers, Trimble R8 receivers, Trimble HPB450 radios, and Trimble TSC2 controllers.

    Date: 2012 (process 2 of 3)
    All SBET shapefiles for each delivery were combined into a single shapefile containing all of the SBET data. Data were reprojected in Alaska Albers Equal Area Conic.

    Date: 2012 (process 3 of 3)
    A metadata file was created to generally describe data acquisition of lidar and also to describe the smooth best estimated trajectory (SBETS) files.

  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Lidar survey datasets were referenced to the 1 Hz static ground GPS data collected over pre-surveyed monuments with known coordinates. While surveying, the aircraft collected 2 Hz kinematic GPS data, and the on-board inertial measurement unit (IMU) collected 200 Hz aircraft attitude data. Waypoint GPS v.8.10 was used to process the kinematic corrections for the aircraft. The static and kinematic GPS data were then post-processed after the survey to obtain an accurate GPS solution and aircraft positions. IPAS v.1.35 was used to develop a trajectory file that includes corrected aircraft position and attitude information. The trajectory data for the entire flight survey session were incorporated into a final smoothed best estimated trajectory (SBET) file that contains accurate and continuous aircraft positions and attitudes.

  2. How accurate are the geographic locations?

    The positional coordinates and attitude of the aircraft were recorded continuously throughout the lidar collection mission. Aircraft position was measured twice per second (2 Hz) by an on-board differential GPS unit during periods with PDOP less than or equal to 3 and with at least 6 satellites in view. Aircraft position was measured twice per second (200 Hz) as pitch, roll and yaw (heading) from an on-board inertial measurement unit (IMU). To allow for post-processing correction and calibration, aircraft/sensor position and attitude are indexed by GPS time. During the lidar survey, static (1 Hz recording frequency) ground surveys were conducted over the survey control monuments. All control monuments were observed for a minimum of two survey sessions lasting no fewer than 4 hours. At the beginning of every session, the tripod and antenna were reset. Indexed by time, GPS data were used to correct the continuous on-board measurements of aircraft position recorded throughout the mission. Control monuments were located within 13 nautical miles of the survey area.

  3. How accurate are the heights or depths?

    The positional coordinates and attitude of the aircraft were recorded continuously throughout the lidar collection mission. Aircraft position was measured twice per second (2 Hz) by an on-board differential GPS unit during periods with PDOP less than or equal to 3 and with at least 6 satellites in view. Aircraft position was measured twice per second (200 Hz) as pitch, roll and yaw (heading) from an on-board inertial measurement unit (IMU). To allow for post-processing correction and calibration, aircraft/sensor position and attitude are indexed by GPS time. During the lidar survey, static (1 Hz recording frequency) ground surveys were conducted over the survey control monuments. All control monuments were observed for a minimum of two survey sessions lasting no fewer than 4 hours. At the beginning of every session, the tripod and antenna were reset. Indexed by time, GPS data were used to correct the continuous on-board measurements of aircraft position recorded throughout the mission. Control monuments were located within 13 nautical miles of the survey area.

  4. Where are the gaps in the data? What is missing?

    Lidar data have been checked for accuracy and completeness. Please refer to the lidar delivery report and lidar QC report for details about data accuracy completeness for individual delivery sets.

  5. How consistent are the relationships among the observations, including topology?

    Consistency refers to lidar elevation differences between overlapping flight lines. Consistency errors are created by poor lidar system calibration settings associated with sensor platform mounting. Errors in consistency manifest as vertical offsets between individual flight lines. Consistency offsets were measured using the "Find Match" tool within the TerraMatch© software toolset. This tool uses aircraft trajectory information linked to the lidar point cloud data to quantify flight line-to-flight line offsets.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
This dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.

  1. Who distributes the data set? (Distributor 1 of 1)

    Alaska Division of Geological & Geophysical Surveys
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (<http://www.dggs.alaska.gov>) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set?

    RDF 2011-3

  3. What legal disclaimers am I supposed to read?

    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity, whether from the use of the electronic services or products, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requestor or anyone else exceed the fee paid for the electronic service or product.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 25-Jul-2012
Metadata author:
Metadata manager
3354 College Road
Fairbanks, AK 99709-3707
USA

(907)451-5020 (voice)

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.2 on Wed Jul 25 17:25:33 2012