2020 AK DGGS Lidar: Haines, Alaska

The Alaska Division of Geological & Geophysical Surveys (DGGS) used aerial lidar to produce a digital terrain model (DTM), surface model (DSM), and intensity image for an area in and around the community of Haines, Alaska, as part of emergency operations in response to the December 2, 2020, landslide that claimed the lives of two residents. Airborne data were collected December 8 - 12, 2020, and subsequently processed in Terrasolid and ArcGIS. Ground control were collected December 15-16, by the DMLW. This data collection is released as a Raw Data File with an open end-user license. All files can be downloaded free of charge from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30595).

The NOAA Office for Coastal Management (OCM) downloaded this data set from this AK DGGS site:

https://elevation.alaska.gov/

These files were processed to the NOAA Digital Coast Data Access Viewer (DAV) and AWS S3. The total number of files downloaded was 209, but only 203 of the 209 files were processed.

In addition to the lidar point data, the bare earth Digital Elevation Model (DEM) data at a 1 meter grid spacing, created from the lidar point data are also available from the NOAA Digital Coast. Links to these data are provided in the URL section of this metadata record.

The Alaska Division of Geological & Geophysical Surveys (DGGS) used aerial lidar to produce a digital terrain model (DTM), surface model (DSM), and intensity image for an area in and around the community of Haines, Alaska, as part of emergency operations in response to the December 2, 2020, landslide that claimed the lives of two residents.

>classified point cloud data: Classified point cloud data is provided in this collection in compressed LAZ format. Data are classified in accordance with ASPRS 2014 guidelines and contain return and intensity information. The average pulse spacing was 10.67 cm and the average density was 87.75 pts/m2 (fig. 2). Elevation surfaces interpolated from areas with a point density of fewer than 4pts/m2 were classified as no data.

>digital surface model: The DSM represents surface elevations, including heights of vegetation, buildings, bridges, etc. The DSM is a single band, 32-bit GeoTIFF file, with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038.

>digital terrain model: The DTM represents 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 1 meter. No Data value is set to -3.40282306074e+038.

>lidar intensity image: The lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is largely a function of scanned object reflectance in relation to the signal frequency, is dependent on ambient conditions, and is not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit float GeoTIFF file with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038 (32-bit, floating-point minimum).

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 NOAA, the Office for Coastal Management or its partners.

Data is available online for bulk and custom downloads.

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.

Horizontal accuracy was not measured for this collection.

A mean offset of 32.3 cm was measured between 31 control points and the point cloud. This offset was reduced to 0 by performing a vertical transformation of the lidar point data. Thirty-six checkpoints were used to determine the vertical accuracy of the point cloud ground class, using a tin-based approach. The final accuracy was calculated to have a root mean square error (RMSE) of 34.8 cm. See accompanying report for more detail.

This data release is complete, and there is no over collect, except for the aircraft turns that were eliminated from the dataset.

The data quality is consistent throughout the survey. The tests and processing methods used to ensure data consistency are further described in the accompanying report.

Data is backed up to tape and to cloud storage.

The data were collected for the Alaska Division of Geological and Geophysical Surveys (DGGS) and made available on the AK DGGS Elevation Portal (https://elevation.alaska.gov/). The NOAA Office for Coastal Management (OCM) downloaded the data from this site to make the data available for custom downloads from the NOAA Digital Coast Data Access Viewer and for bulk downloads from the AWS S3 bucket.