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o VVA < 30 cm 95th Percentile (DEM) <br />Processing <br />Generally, Lidar processing tasks include GPS control computations, kinematic corrections, <br />calculation of laser point position, calibration for optimal relative and absolute accuracy, <br />classification of ground and non -ground points, and creation of ground/digital service models <br />(DSM) . Bare earth classification is accomplished using an automated ground modeling process <br />with visual QA/QC inspection to identify any misclassifications. NV5G, Inc. will employ Lidar <br />ground model parameters appropriate for the project land cover and terrain based on our <br />experience. All methodology and subsequent data products will comply with the most recent <br />U.S. Geological Survey (USGS) Lidar Base Specifications. <br />The bare earth DEM will be hydroflattened to ensure all water bodies are cartographically <br />acceptable and that streams are at or below surrounding terrain. NV5G, Inc. hydroflattening <br />methods use a combination of automated feature edge detection and traditional <br />LiDARgrammetric techniques. The 3-D hydro -line will be used for reclassifying ground points <br />within the wetted area or channel to `water.' Ponds and lakes > 2 acres in size will be <br />hydroflattened at a single elevation with the entire water surface edge at or below the immediate <br />surrounding terrain. Long impoundments whose elevations drop moving downstream will be <br />treated as a river. For rivers > 30 m (100') in average width, hydro -lines will follow the <br />direction of flow (gradient to follow the immediate surrounding terrain) and will be flat and level <br />from bank to bank and at or below immediately surrounding terrain. Streams will break at road <br />crossings, but road fills will not be removed from the DEM. Bridges will be delineated and <br />removed from the DEM. Variations in water surface elevation from tidal variations will not be <br />removed. However, a pseudo -line (no elevation values) will be generated along the tidal <br />shoreline to depict the best estimate of the water's edge at time of collection. <br />Most Current Version of USGS Lidar Base Specification (LBS) Deliverables <br />Classified Point Cloud <br />• Fully compliant Lidar Aerial Survey (LAS) v1.4, Point Record Format 6, 7, 8, 9, or 10 <br />including "File Source ID." <br />• Proper use of the LAS withheld and overlap bits is required. Outlier, blunders, geometrically <br />unreliable points near the extreme edge of the swath, and any other points the data producer <br />deems unusable are to be identified using the withheld bit flag, as defined in LAS specification <br />version 1.4-R13 (ASPRS, 2011).Use of the overlap bit flag is intended to identify overage <br />points, which are described as those points within a given swath that would be excluded when <br />constructing a coverage with a uniform depth of swaths at any location within the project <br />• Geo-reference information included in LAS header (OGC WKT). <br />• GPS times are to be recorded as Adjusted GPS Time, at a precision sufficient to allow unique <br />timestamps for each return. In compliance with LAS specification requirements, the encoding <br />tag in the LAS header must be properly set. <br />• Tiled delivery, without overlap <br />• Classification Scheme (minimum): <br />o Class 1 — Processed, but unclassified <br />o Class 2 — Bare -earth ground <br />o Class 7 — Low Noise (low, manually identified, if necessary) <br />o Class 9 — Water <br />Page3 <br />