NV5 Geospatial 20240322 Raster Digital Data Product: Hydroflattened Digital Elevation Model (DEM) data covering the CA North Sierra 11 2022 project area. Geographic Extent: This dataset and derived products encompass an area covering approximately 1,771 acres of Sierra Nevada Central region. Dataset Description: Lidar flight line swaths were processed to create 4,721 classified LAS 1.4 files delineated in 1,000m x 1,000m tiles. Each LAS file contains lidar point information, which has been calibrated, controlled, and classified. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create 4,721 0.5 meter hydro-flattened Raster DEMs delineated in 1,000m x 1,000m tiles. Non-Vegetated Vertical Accuracy (NVA) was assessed using 0 check points located on bare earth in clear, unobstructed areas. Vegetated Vertical Accuracy (VVA) was assessed using 0 check points in the Tall Grass, Forest, and Shrub landcover types. Additional products include classified LAS files, intensity images, highest hit surface models, and 3D breaklines of rivers and lakes within the study area. Ground Conditions: Acquisition occurred free of smoke, fog and cloud cover. The purpose of the lidar data was to produce a high accuracy 3D dataset that meets all necessary standards laid out by the 3D Elevation Program and the CA North Sierra 11 2022 contract. The lidar point cloud data were used to create classified lidar LAS files, intensity images, interpolated DEMs, hydro-flattened DEMs, highest hit surface models, and 3D breaklines of rivers and lakes within the study area. USGS Contract No. 140G0221D0012 Raster File Type = TIFF Bit Depth/Pixel Type = 32-bit float Raster Cell Size = 0.5 meter Interpolation or Resampling Technique = Triangulated Irregular Network Required Vertical Accuracy = 19.6 cm NVA 20220602 20220825 ground condition Complete As needed -120.060684 -119.322758 38.221184 36.868443 232000.000000 293000.000000 4233000.000000 4084499.367500 none model Raster DEM Bare Earth remote sensing Elevation data Lidar none California These data are considered provisional as they have not yet been reviewed by client or designated agency. None. However, users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations. Acknowledgment of the U.S Geological Survey would be appreciated for products derived from these data. DEM files were tested by NV5 for vertical accuracy. All data is seamless from one tile to the next, no gaps or no data areas. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications. This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 11-cm RMSEz Vertical Accuracy Class. The specifications require that classified Non-vegetated Vertical Accuracy (NVA) be computed from the derived DEMs. The NVA was tested with 0 independent check points located in open terrain and distributed throughout the project as feasible. These check points were not used in the calibration or post processing of the lidar point cloud data. Specifications for this project require that the NVA be 0.196 meters or better AccuracyZ at 95% confidence level. Vegetated Vertical Accuracy (VVA) is also to be computed from the derived DEMS. The VVA was tested with 0 check points in Tall Grass, Forest, Pine, and Shrub land cover types. These check points were also withheld from the calibration and post processing of the lidar point cloud data and distributed throughout the project area as feasible. Specifications for this project require that the VVA be 0.300 meters or better AccuracyZ at the 95th percentile. 0 The 0 independent NVA check points were surveyed using the closed level loop technique. Elevations of the derived bare earth DEMs were compared to the elevation values of the surveyed NVA check points. The RMSE was computed to be 0 meters resulting in an AccuracyZ of 0 meters at the 95% confidence level. NVA AccuracyZ has been tested and meets the required 0.196 meter NVA at 95% confidence level using (RMSEz * 1.9600) for the derived bare earth DEMs as defined by the National Standards for Spatial Data Accuracy (NSSDA) and herein reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines. 0 The 0 VVA check points were surveyed using the closed level loop technique. Elevations for these points were compared to the elevations of the derived bare earth DEMs resulting in an AccuracyZ of 0 meters at the 95th percentile. AccuracyZ has been tested on the derived bare earth DEMs and meets the required 0.300 meter VVA using the 95th percentile of the absolute value of all vertical errors in all combined vegetation classes as defined by the National Standards for Spatial Data Accuracy (NSSDA); and herein reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines. Lidar Pre-Processing: 1. Review flight lines and data 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 sensor head position and attitude recorded throughout the survey. 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 format. Convert data to orthometric elevations by applying a Geoid 18 correction. 5. Import raw laser points into manageable blocks to perform manual relative accuracy calibration and filter erroneous points. Classify ground points for individual flight lines. 6. Using ground classified points per each flight line, test the relative accuracy. Perform automated line-to-line calibrations for system attitude parameters (pitch, roll, heading), mirror flex (scale) and GPS/IMU drift. Calculate calibrations on ground classified points from paired flight lines and apply results to all points in a flight line. Use every flight line for relative accuracy calibration. 7. Adjust the point cloud by comparing ground classified points to supplemental ground control points. CA North Sierra 11 2022 Ground Control 20240322 Lidar Post-Processing: 1. Classify data to ground and other client designated classifications using proprietary classification algorithms. 2. Manually QC data classification 3. After completion of classification and final QC approval, calculate final NVA and VVA values for the project using ground control quality check points. Final density information will also be calculated. 20240322 Hydro-flattening Breaklines and Hydro-flattened DEM creation: Water boundary polygons were developed using an algorithm which weights lidar-derived slopes, intensities, and return densities to detect the water's edge. The water's edge was then manually reviewed and edited as necessary. Elevations were assigned to the water’s edge through neighborhood statistics identifying the lowest lidar return from the water surface. Lakes were assigned a consistent elevation for an entire polygon while rivers were assigned consistent elevations on opposing banks and smoothed to ensure downstream flow through the entire river channel. These breaklines were incorporated into the hydro-flattened DEM by enforcing triangle edges (adjacent to the breakline) to the elevation values derived from the breakline. This implementation corrected interpolation along the hard edge. Breaklines were also used to classify all ground points within the identified water bodies to class 9 (water). 20240322 Raster Pixel 2,000 2,000 Universal Transverse Mercator 11 0.99960000 -117.00000000 0.00000000 500000.00000000 0.00000000 row and column 0.5 0.5 Meters North American Datum of 1983 2011 GRS_1980 6378137.0 298.257222101 North American Vertical Datum of 1988 Geoid 18 0.01 Meters Explicit elevation coordinate included with horizontal coordinates 20240322 20240322 NV5 Geospatial mailing and physical

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