Hubbard, T.D., Koehler, R.D., and Combellick, R.A., 2011, High-resolution lidar data for infrastructure corridors, Gulkana Quadrangle, Alaska: Raw Data File RDF 2011-3O, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
This is a point data set.
Planar coordinates are encoded using row and column
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 North American Datum of 1983.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257222101.
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.
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. Steep slopes with poor access, combined with dense vegetation and a thick moss ground-cover that obscures the bedrock surface, make the use of LiDAR one of the most effective ways to map the geology and evaluate unstable slopes and other hazards.
The American Society for Photogrammetry & Remote Sensing (ASPRS), 02092008, LAS Specification Version 1.2.
Data sources used in this process:
Hubbard, T.D., Koehler, R.D., and Combellick, R.A., 2011, High-resolution LiDAR data for Alaska infrastructure corridors: Raw Data File RDF 2011-3A through RDF 2011-3T, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
Hubbard, T.D., Wolken, G.J., Stevens, D.S.P., and Combellick, R.A., 2013, High-resolution LiDAR data for the Whittier area, Passage Canal, and Portage Lake, Alaska: Raw Data File RDF 2013-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.
LiDAR flight lines have been examined to ensure that there was at least 60% sidelap, there are no gaps between flight-lines, and overlapping flight-lines have consistent elevation values. Shaded relief images were visually inspected for data errors such as pits, border artifacts, gaps, and shifting. The data was examined at a 1:2000 scale. Watershed Sciences, Inc. (WSI) submitted the data to the State of Oregon Department of Geology and Mineral Industries (DOGAMI) for independent quality control analysis. After addressing any concerns from DOGAMI, WSI submitted the revised dataset to DGGS along with a technical report describing details about the LiDAR acquisition, accuracy, and quality. DOGAMI also provided a separate report summarizing their methodologies and the results of quality control checks. Both reports are available via the DGGS website.
Horizontal accuracy refers to the ability to place laser points from multiple flight lines in the same location. Horizontal accuracy is measured as the divergence between points from overlapping flight lines. Accuracy is affected by system attitude offsets, scale and GPS/IMU drift. Manual system calibration and automated attitude calibration techniques were used to resolve divergence of data. Please see the LiDAR QC report and LiDAR delivery report for specific information about accuracy of LiDAR data.
The vertical accuracy of the LiDAR data is described as the mean and standard deviation of divergence between LiDAR point coordinates and RTK ground survey point coordinates. To provide a sense of the model predictive power of the dataset, the root mean-square error (RMSE) for vertical accuracy is also provided. Please see the LiDAR QC report and LiDAR delivery report for specific information about accuracy and quality of LiDAR data, including a comparison of GCP elevations with bare-earth digital elevation model elevations.
The entire dataset for this project consists of: (1) continuous 1-mile-width coverage over existing infrastructure along the entire length of the proposed natural gas pipeline corridors from Prudhoe Bay to the Canada border along the Trans-Alaska Pipeline System (TAPS) and Alaska Highway, from Delta Junction to Valdez along the TAPS, and Livengood to the Anchorage area along the George Parks Highway; (2) approximately 1-mile-wide corridors over routes the State believes gas pipeline applicants are considering, where departing from existing infrastructure; (3) half-mile-wide coverage of existing primary pipeline-support roads where outside the main corridor; and (4) expanded areas of coverage along these corridors where data are needed for evaluation of active faults, slope instability, and other hazards. The average native LiDAR pulse density was >= 8 pulses per square meter over terrestrial surfaces. It is not uncommon for some types of surfaces (e.g. dense vegetation or water) to return fewer pulses than the laser originally emitted. These discrepancies between "native" and "delivered" density will vary depending on terrain, land cover, and the prevalence of water bodies. Please see the LiDAR QC report and LiDAR delivery report for additional information.
Data consistency varies slightly throughout the project area with higher errors in areas of steep terrain. The tests and processing methods used by WSI and DOGAMI to ensure data consistency are described in the accompanying delivery and quality control reports.
Are there legal restrictions on access or use of the data?
- This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
- 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.
The State of Alaska makes no expressed 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.
Current publication is not available on paper. To purchase other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (email@example.com), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard.
|Data format:||LAS v 1.2|
|Data format:||LAS v 1.2|
|Media you can order:||
(format 1 TB USB hard drive)
Please visit: <http://maps.dggs.alaska.gov/lidar/> to download the point cloud data associated with this publication. The complete set of point cloud data is available to users in LAS 1.2 format. The point cloud files total approximately 428GB. The LAS files included in this dataset have been compressed using LASzip. LASzip is an open source lossless compression for LiDAR point cloud data in the LAS format that provides significant file size reductions. To uncompress the included .laz files, you can use the LASzip tool from our web site: <http://maps.dggs.alaska.gov/lidar/bin/laszip.exe>, or download the latest version directly from <http://laszip.org>. Due to the size of these files we also offer the option to receive this data on a USB hard drive. There are two options for copying the data to a hard drive: (1) DGGS will purchase a brand-new, 1 TB hard drive that you will be billed for when the data is picked up or sent, OR (2) you may provide a new, unopened* (in original packaging, including shrink-wrap - *The State of Alaska IT security policy prohibits non-State resources from being connected to a State of Alaska network. Thus, only unused drives can be used.) 1 TB or larger hard drive. For all orders, please include: title and publication number.