Sanborn Map Company, Inc. 20200727 vector data Product: 3D hydro flattened breaklines in GDB format. Geographic Extent: Brazos County, TX, covering the approximately 155 square miles. Dataset Description:The College_Station_TX_Lidar project called for the planning, acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 meters (QL1). Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.3. The data was developed based on a horizontal projection/datum of NAD83 (2011), State Plane, U.S. Survey Feet and vertical datum of NAVD88 (GEOID12B), Feet. Lidar data was delivered as processed Classified LASv1.4 files, formatted to 794 individual 2,500 ft x 2,500 ft tiles clipped to the BPA, and as 794 individual 2,500 ft x 2,500 ft tiled intensity imagery, tiled bare-earth DEMs, and contours. Ground Conditions: Lidar was collected in early 2020, 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, The Sanborn Map Company, Inc. established a total of 7 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 25 independent accuracy check points, 20 in Open Terrain/Bare-Earth and Urban landcovers (20 NVA points), 5 in Grass, Brush and Trees categories (5 VVA points), were used to assess the vertical accuracy of the data. These check points 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 foot cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, hydro-flattened DEMs, and contours necessary. Hydro-flattened breaklines in Esri file geodatabase format with monotonic downhill treatment. 20200225 20200227 ground condition Complete None planned -96.4234904459 -96.1359033831 30.6584128237 30.4440751502 None Model Breaklines Elevation Data Lidar None Texas Brazos 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 its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data. Data covers the entire area specified for this project. Breaklines were collected in all inland ponds and lakes ~2 acres or greater. These features were flat and level water bodies at a single elevation for each vertex along the bank. The entire water surface edge is at or below the immediate surrounding terrain. Breaklines were collected for all streams and rivers ~100' nominal width or wider. These features are flat and level bank to bank, gradient will follow the surrounding terrain and the water surface will be at or below the surrounding terrain. Streams/river channels will break at culvert locations however not at elevated bridge locations. All files are inspected to ensure that they conform to the specified file naming conventions, all files load in their correct geographic position, all files conform to the project specifications for file standard and content. Hydro-Flattening Breakline Processing: Class 2 (ground) lidar points were used to create a bare-earth surface model. The surface model was then used to heads-up digitize 2D breaklines of inland streams and rivers with a ~100' nominal width and Inland Ponds and Lakes of ~2 acres or greater surface area. Elevation values were assigned to all Inland Ponds and Lakes, Inland Pond and Lake Islands, Inland Stream and River Islands, using LP360 functionality. Elevation values were assigned to all Inland streams and rivers using LP360 functionality. All ground (ASPRS Class 2) lidar data inside of the collected inland breaklines were then classified to water (ASPRS Class 9) using LP360 functionality. A buffer of 1 foot was also used around each hydro-flattened feature. These points were moved from Ground (Class 2) to Ignored Ground (Class 20). The breakline files were then translated to ESRI File-Geodatabase format using ESRI conversion tools. Breaklines are reviewed against lidar intensity imagery to verify completeness of capture. All breaklines are then compared to TINs (triangular irregular networks) created from ground only points prior to water classification. The horizontal placement of breaklines is compared to terrain features and the breakline elevations are compared to lidar elevations to ensure all breaklines match the lidar within acceptable tolerances. Some deviation is expected between breakline and lidar elevations due to monotonicity, connectivity, and flattening rules that are enforced on the breaklines. Once completeness, horizontal placement, and vertical variance is reviewed, all breaklines are reviewed for topological consistency and data integrity using a combination of ESRI Data Reviewer tools and proprietary tools. 20200724 Vector NAD 1983 2011 StatePlane Texas Central FIPS 4203 Ft US 31.88333333333333 30.11666666666667 -100.3333333333333 29.66666666666667 2296583.333 9842500.000000002 coordinate pair 0.001 0.001 foot D NAD 1983 2011 GRS 1980 6378137.0 298.257222101 North American Vertical Datum of 1988 0.001 foot Explicit elevation coordinate included with horizontal coordinates 20200727 The Sanborn Map Company, Inc. mailing and physical

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