boundaries: A boundary, also known as an Area of Interest (AOI) or border, that defines the area covered by the data. Also includes footprints for tiled data. classified_points: Classified point cloud data are provided in LAZ format. Data are classified following ASPRS 2019 guidelines and contain return and intensity information. For classified ground points, the average point density is 12.4 pts/m2 and the average spacing is 28.4 cm; within the high-priority region, the average ground point density is 11.5 pts/m2 and the average spacing is 29.4 cm. dsm: The DSM represents surface elevations, including heights of vegetation, buildings, powerlines, bridge decks, etc. The DSM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum). The DSM from the high-priority area is a single-band, 32-bit GeoTIFF file of 20-cm resolution, with a No Data value of -3.40282306074e+38. dtm: The DTM represents bare earth or snow surface elevations, excluding vegetation, bridge decks, buildings, etc. The DTM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38. The DTM from the high-priority area is a single-band, 32-bit GeoTIFF file of 20-cm resolution, with a No Data value of -3.40282306074e+38. lidar_intensity: The lidar intensity image illustrates the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is (1) primarily a function of scanned object reflectance in relation to the signal frequency, (2) dependent on ambient conditions, and (3) not necessarily consistent between separate scans. The intensity image is a single-band, 16-bit unsigned GeoTIFF file of 20-cm resolution. No Data value is set to 0.
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This survey area lies within the traditional homelands of the Tlingit peoples. This work was funded by the Alaska Department of Military and Veterans Affairs Division of Homeland Security and Emergency Management through emergency response funds from the Federal Emergency Management Agency. We thank Coastal Helicopters for their expertise and contribution to these data products and Temsco Helicopters for allowing us to use their facilities. We also thank the residents, first responders, and road clearing workers of Ketchikan for allowing us to operate in the landslide area. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the State of Alaska.
The data were collected during leaf-on conditions and provides snow-free surface elevations useful for landslide hazard analysis. The Division of Geological and Geophysical Surveys (DGGS) conducted the lidar survey following a fatal landslide in downtown Ketchikan on August 25, 2024.
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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.
The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services 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, any failure thereof, or otherwise, and 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.
| Data format: | boundaries, classified points, dsm, dtm and lidar intensity in format data |
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http://dx.doi.org/10.14509/31453 |