2012 Alaska Division of Geological and Geophysical Surveys (DGGS) Lidar: Whittier, Alaska

In support of geologic mapping and hazards evaluation in and near Whittier, Alaska, the Division of Geological and Geophysical Surveys (DGGS)

acquired, and is making publicly available, lidar (light detection and ranging) data for an area along Passage Canal, Portage Lake, and

Portage Glacier Highway. The lidar data, acquired between 21 - Oct 25 2013, was processed by Watershed Sciences, Inc. (WSI) and consists of

continuous coverage encompassing an area extending from Portage Lake eastward to Logging Company Bay in Passage Canal in the Seward D-4,

D-5, and D-6 1:63,360-scale quadrangles.

Lidar data collected below 1,600 ft (488 m) elevation have a minimum average pulse density of 8 pulses/square meter; above 1,600 ft (488 m)

data were collected with an average pulse density of at least 4 pulses/square meter. Following lidar data collection and processing by WSI

and their survey subcontractor, McClintock Land Associates, 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.

The following data classifications are available for download from the NOAA Digital Coast:

1 (Unclassified)

2 (Ground)

3 (Low Vegetation)

4 (Medium Vegetation)

6 (Buildings)

7 (Low Point/Noise)

9 (Water Surface)

10 (Ignored Ground - Ground points within 1 m of breaklines)

14 (Withheld - Points that have intensity values of 0 or 255)

15 (Mobile - Temporary Placed Structures (cars, boats, docks, buoys))

16 (Utilities - Man made non-habitable structures (fences, power lines))

Original contact information:

Contact Name: James Weakland

Contact Org: Alaska Division of Geological and Geophysical Surveys

Title: GIS Analyst

Phone: (907)451-5029

Email: dggsgis@alaska.gov

In support of geologic mapping and hazards evaluation in and near Whittier, Alaska, the Division of Geological and Geophysical Surveys (DGGS)

acquired, and is making publicly available, lidar (light detection and ranging) data for an area along Passage Canal, Portage Lake, and

Portage Glacier Highway. Data will serve multiple purposes but were primarily collected to map geology and evaluate potential geologic hazards.

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.

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This metadata file was written to document and describe, as a whole, all the lidar data products generated for this project. It provides

a brief overview to the data acquisition, processing, and quality control steps utilized by DGGS contractors and subcontractors. Watershed

Sciences, Inc. has associated additional metadata (via ArcGIS) with many of the distribution files. The metadata fields populated by WSI are

viewable via ArcCatalog and may include additional useful information that is specific to each individual file. However, WSI metadata has not

been reviewed by DGGS/DOGAMI to ensure accuracy and completeness. We encourage users to review the delivery and quality control reports

provided by Watershed Sciences, Inc. and DOGAMI for a comprehensive discussion of their processes.

The Quality Control Report may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_qc_report.pdf

The Delivery Report may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_delivery_report.pdf

A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/2012_DGGS_Whittier_Alaska_Lidar.kmz

The appropriate citation for this infomation is:

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: Alaska Division of Geological and Geophysical Surveys Raw Data File 2013-3, 5 p. http://doi.org/10.14509/24976

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.

Any conclusions drawn from the analysis of this information are not the responsibility of Alaska DGGS, the Office for Coastal Management

or its partners.

This data can be obtained on-line at the following URL:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2580

This data set is dynamically generated based on user-specified parameters.

;

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no

longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its

limitations.

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 and 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.

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 have been visually inspected for data errors such as pits, border

artifacts, gaps, and shifting. The data was examined at a 1:2000 scale. 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 data set 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 or at:

The Quality Control Report may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_qc_report.pdf

The Delivery Report may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_delivery_report.pdf

Horizontal accuracy is regarded as a product of the lidar ground footprint. Lidar is referenced to co-acquired GPS base station data that

have accuracies far greater than the value of the lidar footprint. The ground footprint is equal to 1/3333rd of the above - ground flying

height. The ground footprint for data collected for this project exceeds typical accuracy of ground control used to reference the lidar

data (less than 0.01 meters). Project specifications require the lidar footprint to be between 0.15 and 0.40 meters. The values, tests,

and processing methods used by WSI and DOGAMI to ensure relative accuracy are described in the accompanying delivery and quality control

reports. Please see the lidar QC report at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_qc_report.pdf

The vertical accuracy for this data set is 2.2 cm RMSE.

Vertical accuracy was assessed by comparing GPS survey collected by McClintock Land Associates with lidar digital elevation models to expose

offsets. Quality control analysis performed by DOGAMI, indicate that the data complies with project specifications (maximum root mean square

vertical offset - 0.20 meters). Please see the lidar QC report for statistics from vertical accuracy analysis at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_qc_report.pdf

The pulse density distribution varies throughout the study area. Areas below 1,600 feet in elevation, including the City of Whittier, were

collected at a higher pulse density (greater or equal to 8 pulses/square meter), with areas above 1,600 feet in elevation collected at greater

than or equal to 4 pulses/square meter. The WSI delivery report provides additional information about the lidar pulse density and distribution.

Real time kinematic ground survey data (used for absolute vertical adjustment) is available in Appendix A of the delivery report. Aircraft

flight-lines (trajectory files) were supplied to DOGAMI for quality control but are not included as a component of this publication.

The Delivery Report may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_delivery_report.pdf

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 which may be accessed at:

The Quality Control Report may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_qc_report.pdf

The Delivery Report may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/2580/supplemental/rdf2013_003_delivery_report.pdf