New York Office of Information Technology Services Unpublished Material raster digital data Product: These are Digital Elevation Model (DEM) data for Chautauqua and portions of Cattaraugus Counties, New York as part of the required deliverables for the Southwest 17 Spring Lidar project. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened Raster DEM. Geographic Extent: Chautauqua and Cattaraugus County, New York, covering approximately 1,722 square miles. Dataset Description: Chautauqua and Cattaraugus County, New York 2017 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 U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83(2011), Universal Transverse Mercator Zone 17 N, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS 1.4 files, formatted to 1982 individual 1500 m x 1500 m tiles, as tiled bare earth DEMs; all tiled to the same 1500 m x 1500 m schema. Ground Conditions: Lidar was collected in early 2017, 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 established a total of 32 ground control points that were used to calibrate the lidar to known ground locations established throughout the Chautauqua and Cattaraugus County, New York project area. An additional 128 independent accuracy checkpoints, 75 in Bare Earth and Urban landcovers (75 NVA points). 53 in Tall Grass and Brushland/Low Trees categories (53 VVA points) were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. 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 Intensity Images, 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. USGS Contract No. G17AC00096 CONTRACTOR: New York Office of Information Technology Services. SUBCONTRACTOR: Axis Geospatial, LLC Lidar data were acquired and calibrated by Axis GeoSpatial, LLC. All follow-up processing was completed by the prime contractor. This material is based upon work supported by the Natural Resources Conservation Service, U.S. Department of Agriculture, under number 68-2C31-17-099. 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 20170418 20170509 ground condition Complete None planned -79.768477 -78.718362 42.581543 41.985952 None Raster DEM Elevation Data Lidar None New York Chautauqua County Cattaraugus 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 10 (Ignored Ground) next to the hydro breaklines has eliminated ground points on a small berm or raised bank. Datasets contain complete coverage of tiles. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. There are no void areas or missing data. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications. Points with extreme elevations (negative values, or positive values well above the expected maximum) are present in this dataset. These points are classified as low or high noise in classified point cloud tiles. 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 75 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: 29.4 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 53 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. .085 Tested 0.043 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 75 independent checkpoints located in the Bare Earth and Urban land cover categories. .181 Tested 0.093 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 VVA of the DEM was calculated using 53 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. 2017 Raster Pixel 1500 1500 Universal Transverse Mercator 17 0.9996 -81.00 0.0 500000 0.0 coordinate pair 0.01 0.01 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 20171115 New York Office of Information Technology Services mailing and physical

10B Airline Drive

Albany NY 12235 USA (518)242-5061 FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998