point cloud data: Classified lidar values. Points were classified in accordance with ASPRS 2014 guidelines. digital surface model: DSMs represent surface elevations, as they appear to the naked eye. They include the heights of vegetation, buildings, bridges, etc. The DSM is a single band, 32-bit GeoTif file, with a ground sample distance of .5 meters. No Data value is set to -3.40282306074e+038. digital terrain model: DTMs represent surface elevations of ground surfaces, excluding vegetation, bridges, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file, with a ground sample distance of .5 meters. No Data value is set to -3.40282306074e+038.
Daanen, R.D., Wolken, G.J., and Herbst, A.M., 2020, High-resolution lidar data from the west Susitna area, Southcentral, Alaska: Raw Data File RDF 2020-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
This is a raster data set.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest .00000001
Ordinates (y-coordinates) are specified to the nearest .00000001
Planar coordinates are specified in Meters
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is GRS 80.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257222101000025.
These data were collected and processed by the Alaska Division of Geological and Geophysical Surveys staff with funding from the Alaska Industrial Development and Export Authority.
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This dataset includes point cloud data and two 32-bit raster elevation models that cover an area of interest for proposed infrastructure development in the west Susitna region.
Airborne data were collected on November 4-10, 2019. Weather conditions were generally sub-optimal throughout the survey, requiring operations to take place in thick fog and low-lying clouds, at the risk of increased levels of noise in the product. Snow was present across the majority of the study area surface and accumulated throughout the survey period, especially in the northernmost section. Weather conditions and snow cover resulted in variability of point density throughout the study area. See accompanying report for further discussion of data verification procedures.
Trimble R8 and R9 RTK GPS systems were used to collect ground control points (GCPs). Seventy-five checkpoints were used to calculate a vertical accuracy of 39 cm RMSE. Internal consistency for the point cloud data was measured at 6.5cm across the project. Points were adjusted for accuracy, according to OPUS corrections, in Trimble Business Center. See accompanying report for a table of checkpoints and further discussion of factors impacting the certainty of data locations.
Seventy-five checkpoints were used to calculate a vertical accuracy of 39 cm RMSE. Relative accuracy was evaluated as the interswath consistency and was measured at 2.1 cm RMSE. The quality of the data is the average elevation compared to an independent dataset. The second aspect of the quality of the data is related to point density distribution over the survey area. The average point density is 10.23 points per square meter. A table of checkpoints and errors is provided in the accompanying report.
Elevation surfaces interpolated from areas with a point density of fewer than 1pts/m^2 were classified as nodata. This data release is complete.
The tests and processing methods used to ensure data consistency are described in the accompanying report.
Are there legal restrictions on access or use of the data?
- Access_Constraints:
- 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).
- 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.
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RDF 2020-5
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.
DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or email from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount.
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| Network links: |
<http://doi.org/10.14509/30455> |
(907)451-5020 (voice)
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