Wikstrom Jones, Katreen
Wolken, G.J.
Whorton, E.N.
Hendricks, M.D.
2019
Photogrammetry-derived digital surface model and orthoimagery of Valdez Glacier ice-dammed lake, Valdez, Alaska, October 15, 2014
digital surface model
Raw Data File
RDF 2019-2
Fairbanks, Alaska, United States
Alaska Division of Geological & Geophysical Surveys
4 p.
http://doi.org/10.14509/30181
The State of Alaska Division of Geological & Geophysical Surveys (DGGS) produced a digital surface model (DSM) and an orthorectified aerial image over an ice-dammed lake formed by Valdez Glacier. Aerial photographs and Global Navigation Satellite System (GNSS) data were collected on October 15, 2014, and were processed using Structure-from-Motion (SfM) photogrammetric techniques to create a DSM and orthoimagery. For the purpose of enabling open access to geospatial datasets in Alaska, this collection is being released as a Raw Data File with an open end-user license. All files can be downloaded free of charge from the DGGS website (http://doi.org/10.14509/30181).
This data release is one of a series of Alaska Division of Geological & Geophysical Surveys (DGGS) publications to present elevation data collected prior to and after the annually recurring glacial lake outburst floods (GLOFs) at Valdez Glacier. The goal is to provide information for the City of Valdez to better understand the complex nature of these phenomena.
>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 file, with a ground sample distance (GSD) of 0.19 m. No Data value is set to -32767.
2014
ground condition
None planned
-146.172
-145.986
61.245
61.197
ISO 19115 Topic Category
geoscientificInformation
Alaska Division of Geological & Geophysical Surveys
Coastal
Coastal and River
Digital Surface Model (DSM)
Engineering
Engineering Geology
Environmental
Flood
Geologic
Geologic Hazards
Geological Process
Glacial
Glacial Geomorphology
Glacial Lake
Glacial Processes
Glacier Flood
Glacier Outburst Flood
Glaciers
Glaciology
Ice
Lake Level
Lakes
Structure From Motion
Surface
Water
Alaska Division of Geological & Geophysical Surveys
Valdez
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.
Alaska Division of Geological & Geophysical Surveys
Metadata Manager
mailing and physical
3354 College Road
Fairbanks
AK
99709-3707
USA
(907)451-5020
(907)451-5050
dggspubs@alaska.gov
8 am to 4:30 pm, Monday through Friday, except State holidays
These data products were funded by City of Valdez and Alaska Department of Natural Resources, Division of Geological & Geophysical Surveys. We thank Alpine Air for their aviation expertise and contribution to these data products.
The DSM and orthoimagery have been visually inspected for data errors such as pits, border artifacts, and shifting. The end-user should be aware that pits and peaks are present in areas of some small water bodies, such as lakes and ponds, and that DSM data have not been hydro-flattened in these areas.
Ground control points were not collected at the time of acquisition.
The State of Alaska Division of Geological & Geophysical Surveys collected digital aerial photographic data on October 15, 2014, using a rotary-wing (Robinson 44) airborne platform. The aerial photographic survey resulted in approximately 60 percent side lap and 80 percent end lap coverage, with an above ground-level flying height of 1100-2000 m, which resulted in 818 photos with 0.096 m per pixel ground resolution. The total area surveyed was approximately 11 km2. This data release is complete.
All data are projected in UTM Zone 6 North (meters) using the NAD83 (2011; EPSG 6335) horizontal datum. The average camera location error was 0.12 m in the X direction (0.12 m in the Y direction), 0.14 m in the Z, combined XY error of 0.17 m. and resulting total error of 0.22 m. No ground control points, check points, or other reference datasets were available to assess the horizontal accuracy of the resulting digital surface model and orthoimagery.
All data utilize the NAVD88 (Geoid12A; EPOCH 2010.00) vertical datum. No ground control points, check points, or other reference datasets were available to assess the vertical accuracy of the resulting digital surface model and orthoimagery.
Data acquisition - The State of Alaska Division of Geological & Geophysical Surveys collected digital aerial photographic data on October 15, 2014, using a rotary-wing (Robinson 44) airborne platform. The aerial photographic survey resulted in approximately 60 percent side lap and 80 percent end lap coverage, with an above ground-level flying height of 1100-2000 m, which resulted in 818 photos with 0.096 m per pixel ground resolution. The total area surveyed was approximately 11 km2. A Nikon D800 with an AF-Nikkor 28mm f/5D lens was used to collect 36.2-megapixel JPEG photographs (7360 x 4912 pixels per image) which were compressed for optimal quality. The aerial photographic survey was controlled with a custom intervalometer that linked the camera shutter release with Global Positioning System (GPS) event markers. GPS event markers were created by an onboard Topcon Net G3 receiver and a dual-band Topcon PG-A1 antenna mounted approximately 0.02 m above the camera, with a background sampling frequency of 5 Hz. A GPS base station with a Topcon Hyper-II receiver sampling at 1 Hz was placed approximately 10 km from the survey area and was used to differentially correct the aerial survey GPS data using post-processing kinematic (PPK) methods. Ground control points were not collected at the time of acquisition.
2014
GNSS data processing - Aerial survey GNSS data (camera coordinates and trajectory data) were processed by DGGS using kinematic (PPK) methods in Topcon Positioning Systems, Inc. Magnet Office Tools commercial GNSS software. Nearby CORS stations were used as the vertical and horizontal control. GNSS data were collected and processed in WGS84 (G1674) using WGS84 ellipsoid. The base station position was corrected using the NGS Online Positioning User Service (OPUS) with the IGS08 (EPOCH 2015.6162). Camera coordinates were converted to the North American Datum 1983 (NAD83; 2011) European Petroleum Survey Group Well Known Identification Number (EPSG) 6335 and the North American Vertical Datum of 1988 (NAVD88; Geoid12A; EPOCH 2010.00) using the National Geodetic Survey (NGS) VDatum tool (version 3.3). The coordinates are projected in UTM Zone 6 North and are in meters. The converted camera coordinates were manually correlated to image filenames to create a camera exterior orientation file for import into the photogrammetric software, Agisoft Photoscan Professional. The exterior orientation file provides the X, Y, and Z position for each photograph taken during the survey. Yaw, pitch, and roll information were not recorded during the flight.
2014
Photogrammetry - Aerial stereo-photographs were imported into the commercially available Agisoft Photoscan Professional software (Version 1.2.3 build 2331). Photos were processed in Photoscan on a Windows PC to align aerial photos, edit the sparse point cloud, optimize the bundle block adjustment, construct the dense point cloud and triangulated irregular network geometry, and export the natural color (RGB) orthoimagery GeoTIFF.
2014
raster
Universal Transverse Mercator
6
0.999600
-147
0
500000.000000
0
coordinate pair
.00000001
.00000001
Meters
North American Datum of 1983
GRS 80
6378137
298.257222101000025
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 file, with a ground sample distance (GSD) of 0.19 m. No Data value is set to -32767
Alaska Division of Geological & Geophysical Surveys (DGGS)
digital surface model
Alaska Division of Geological & Geophysical Surveys
Metadata Manager
mailing and physical
3354 College Road
Fairbanks
AK
99709-3707
USA
(907)451-5020
(907)451-5050
dggspubs@alaska.gov
8 am to 4:30 pm, Monday through Friday, except State holidays
RDF 2019-2
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.
Contact DGGS for current pricing
digital surface model
http://doi.org/10.14509/30181
Free download
20190618
Alaska Division of Geological & Geophysical Surveys
Simone Montayne
Metadata Manager
mailing and physical
3354 College Road
Fairbanks
AK
99709-3707
USA
(907)451-5020
(907)451-5050
dggspubs@alaska.gov
8 am to 4:30 pm, Monday through Friday, except State holidays
FGDC Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998
If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys.
http://www.dggs.alaska.gov/metadata/dggs.ext
dggs metadata extensions