New York Office of Information Technology Services Unpublished Material raster digital data Product: Calibrated LiDAR version 1.4 .las tiles, classified to bare earth for subsequent derivatives. Geographic Extent: Erie, Genesee, and Livingston Counties, New York, covering approximately 2,188 square miles. Dataset Description: Erie, Genesee, and Livingston Counties, New York 2019 Lidar project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.7 meter. Project specifications are based on the USGS LIDAR Base Specifications Version 1.3. The data was developed based on a horizontal projection/datum of NAD83(2011), Conus Albers, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 5667 individual 1000 m x 1000 m tiles, as tiled bare earth DEMs; all tiled to the same 1000 m x 1000 m schema. Ground Conditions: Lidar was collected in the spring 2019, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, New York Office of Information Technology Services provided a total of 44 ground control points that were used to calibrate the lidar to known ground locations established throughout the Erie, Genesee, and Livingston Counties, New York project area. An additional 214 checkpoints, 111 NVA in Bare Earth and Urban landcover and 103 VVA in Tall Grass and Brushland/Low Trees categories were surveyed by Axis Geospatial, LLC to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. 4 of the 111 NVA checkpoints fell beyond the contracted project limits and were not used for the NVA assessment of the DEMs but were used for the NVA assessment of the swaths. To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 1 meter cell size. These raw lidar point cloud data were used to create classified lidar LAS files, 3D breaklines, hydro-flattened DEMs as necessary. Raster File Type = IMG Bit Depth/Pixel Type = 32-bit float Raster Cell Size = 1 Meter Interpolation or Resampling Technique = Triangulated Irregular Network Required Vertical Accuracy = 19.6 cm NVA 20190425 20190515 ground condition Complete None planned -79.18841 -77.384061 43.276981 42.241447 None Raster DEM Elevation Data Lidar None New York Erie County Genesee County Livingston County No restrictions apply to these data. 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 the limitations of the data. Acknowledgement of New York Office of Information Technology Services would be appreciated for products derived from these data. The data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of the data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose. Data covers the entire area specified for this project. Partially elevated water bodies may be present where use of Class 20 (Ignored Ground) next to the hydro breaklines has eliminated ground points on a small berm or raised bank. These LAS data files include all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. You may see data voids where caused by areas of low near infrared reflectivity, such as asphalt or composition roofing. We have seen these dropouts on building rooftops throughout this project. Also, there are extreme positive and negative Z values within the LiDAR pointcloud. We have classified these points as Class 7 (Low Point) and/or Class 18 (High Point) to accommodate for these values. Partially elevated water bodies may be present where use of Class 20 (Ignored Ground) next to the hydro breaklines has eliminated ground points on a small berm or raised bank. The project specifications require the accuracy (ACCz) of the derived DEM be calculated and reported in two ways: 1. The required NVA is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in the “bare earth” and "urban" land cover classes. This is a required accuracy. The NVA was tested with 107 checkpoints located in bare earth and urban (non-vegetated) areas. 2. Vegetated Vertical Accuracy (VVA): VVA shall be reported for "brushlands/low trees" and "tall weeds/crops" land cover classes. The target VVA is: 30.0 cm at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for Lidar Data, i.e., based on the 95th percentile error in all vegetated land cover classes combined. This is a target accuracy. The VVA was tested with 103 checkpoints located in tall weeds/crops and brushlands/low trees (vegetated) areas. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines. .106 Tested 0.054 meters RMSEz at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the DEM was calculated using 107 independent checkpoints located in the Bare Earth and Urban land cover categories. .164 Tested 0.087 meters RMSEz at a 95% percentile. The VVA of the DEM was calculated using 103 checkpoints located in the Brushlands and Low Trees and Tall Weeds and Crops land cover categories. Hydro Flattened Raster DEM Process: Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened Raster DEM. Using LasTools a merged large scale Imagine IMG file was created and then cut into tiles using Global Mapper. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface. 2018 Raster Pixel 1000 1000 Albers Conical Equal Area 29.500000 45.500000 -96.00 23.0 0.0 0.0 coordinate pair 0.1 0.1 meters North American Datum of 1983 (2011) Geodetic Reference System 80 6378137 298.257222101 North American Vertical Datum of 1988 (Geoid12B) 0.01 meters Explicit elevation coordinate included with horizontal coordinates 20190330 New York Office of Information Technology Services mailing and physical

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