digital surface model: DSMs represent surface elevations of all surfaces, including vegetation, vegetation-free land, bridges, buildings, etc. The DSM is a single-band, 32-bit float GeoTIFF files using Lempel-Ziv-Welch (LZW) compression, with a ground sample distance (GSD) of 0.41 m. The No Data value is set to -32767.
Balazs, M.S., Wolken, G.J., and Wikstrom Jones, Katreen, 2018, Photogrammetry-derived digital surface model and orthoimagery of land areas near Resurrection Bay, Alaska: Raw Data File RDF 2018-2, 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.
This project is funded by Seward Bear Creek Flood Service Area, Kenai Peninsula Borough, DGGS through a State of Alaska Capital Improvement Project, and the University of Alaska Fairbanks, Geophysical Institute.
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DSMs represent surface elevations of all surfaces, including vegetation, vegetation-free land, bridges, buildings, etc. The DSM is a single-band, 32-bit float GeoTIFF files using Lempel-Ziv-Welch (LZW) compression, with a ground sample distance (GSD) of 0.41 m. The No Data value is set to -32767. This file was created for ongoing investigation of the impact of flooding, slope instability, and cryosphere hazards on infrastructure and public safety in the the Resurrection Bay watershed. Data were collected on August 13, 2015.
The DSM a ground sample distance (GSD) of 0.41 m, and the No Data value is set to -32767. The orthoimage has a GSD of 0.2 m per pixel, and the No Data value is set to 0. The DSM and orthoimagery have been visually inspected for data errors such as pits, border artifacts, and shifting. Pits and peaks are present over water bodies such as lakes. The end-user should be aware that DSM data were not hydro-flattened. Some small areas along the boundary and northern region of the survey area have NO DATA values, which is due to insufficient overlap (gaps) in the aerial photographic survey in areas of extreme topographic relief. The end user is advised that such areas may have a less accurate geographic position than reported for the rest of the scene.
Horizontal accuracies of the orthoimagery and DSM were assessed using 19 photo-identifiable checkpoints along the road systems in and near Seward, Alaska. Lower horizontal accuracy is possible in areas of extreme terrain, dense vegetation, and heavy shadow. The X-coordinates have a root-mean-square error (RMSE) of 0.32m and a mean absolute error (MAE) of 0.28 m. The Y Coordinates have an RMSE of 0.47 m and a MAE of 0.42 m. The horizontal linear RMSE in the radial direction (RMSEr) is 0.57 m. See accompanying report for additional detail.
Vertical accuracy of the DSM was assessed by comparing the elevation values of 22 checkpoints (described above; fig 2 of the accompanying report.) to the elevation values at the same location in the DSM. The mean vertical offset is 0.12 m, with a RMSE of 0.38 m and a MAE of 0.28 m. An additional evaluation of the vertical accuracy of the DSM was performed by comparing randomly sampled elevation values of points (n = 2876) on the road network from a LiDAR-derived digital elevation model (2009) to the elevation values at the same location in the DSM. The mean vertical offset is 0.24 m, with a RMSE of 0.42 m and a MAE of 0.28 m.
This data release is complete.
The aerial photography survey used a fixed-wing airborne platform and was planned so flight lines and photograph frequency provided 60 percent side lap and 80 percent end lap coverage, with an average above-sea-level flying height of 1260 m. The aerial photography survey covered 383 km2, resulting in 4021 photos with 0.2 m ground sample distance (GSD). Nineteen photo-identifiable checkpoints were collected by University of Alaska Fairbanks, Geophysical Institute personnel in September 2015 using two Trimble R8s GPS receivers. Checkpoint locations and offsets are provided 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 2018-2
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.
| Data format: | digital surface model |
|---|---|
| Network links: |
<http://doi.org/10.14509/29824> |
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