Data Management Plan (Deprecated)

This dataset is LiDAR point cloud data, which encompasses a 100 meter buffer around the Juneau,AK study area, approximately 121,313 acres. Dataset Description: This dataset consists of 1273 .LAS files delineated in 750 x 750 m tiles and named as specified by the client. Each .LAS file contains LiDAR point information, which has been calibrated, controlled, and classified. LAS points contain RGB values from orthoimagery mosaics. Normalized intensity values are represented in the intensity field in this version of the point cloud. Ground Conditions: LiDAR acquisition of near shore areas was prioritized to coincide with the lowest tides possible, within constraints of daily local weather patterns. Leaf-off, no snow conditions were targeted in all other areas given the diverse terrain represented in the study area.

The LAZ files have vertical georeferencing using the EPSG 5866 code for mean lower low water. However, this code is for depth while the data is in height. There was no appropriate code for MLLW height at the time.

Process Steps:

• 2013-09-30 00:00:00 - LiDAR Pre-Processing: 1. Flight lines and data were reviewed to ensure complete coverage of the study area and positional accuracy of the laser points. 2. Resolve kinematic corrections for aircraft position data using kinematic aircraft GPS and static ground GPS data. 3. Develop a smoothed best estimate of trajectory (SBET) file that blends post-processed aircraft position with attitude data. Sensor head position and attitude are calculated throughout the survey. The SBET data are used extensively for laser point processing. 4. Calculate laser point position by associating SBET position to each laser point return time, scan angle, intensity, etc. Create raw laser point cloud data for the entire survey in *.las (ASPRS v. 1.2) format. Data are converted to orthometric elevations (NAVD88) by applying a Geoid12a correction. 5. Import raw laser points into manageable blocks (less than 500 MB) to perform manual relative accuracy calibration and filter erroneous points. Ground points are then classified for individual flight lines (to be used for relative accuracy testing and calibration). 6. Using ground classified points per each flight line, the relative accuracy is tested. Automated line-to-line calibrations are then performed for system attitude parameters (pitch, roll, heading), mirror flex (scale) and GPS/IMU drift. Calibrations are calculated on ground classified points from paired flight lines and results are applied to all points in a flight line. Every flight line is used for relative accuracy calibration. 7. Assess statistical absolute accuracy via direct comparisons to ground RTK survey data.
• 2013-09-30 00:00:00 - LiDAR Post-Processing: 1. Classify data to ground and other client designated classifications using proprietary classification algorithms. 2. Manually QC data classification 3. Normalize Intensity Values for receiver auto gain control, atmospheric effects, and angle of incidence. 4.Apply RGB values from orthophotos to points.
• 2022-09-13 00:00:00 - The NOAA Office for Coastal Management (OCM) received the files in laz format from USGS via an FTP online repository. The files contained lidar elevation and intensity measurements. The data were in UTM Zone 5, mean lower low water heights in meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The data were converted from UTM coordinates to geographic coordinates. 2. Duplicate points were removed

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=4813

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