2009 - 2011 CA Coastal Conservancy Coastal Lidar Project: Hydro-flattened Bare Earth DEM

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Fugro EarthData, Inc. collected ALS60-derived LiDAR over Coastal California with a 1 meter, nominal post spacing

using two Piper Navajo twin engine aircrafts. The collection for the entire project area was accomplished between October 2009 and

August 2011; 1,546 flight lines were acquired in 108 lifts. The lines were flown at an average of 6,244 feet above mean terrain

using a pulse rate of 121,300 pulses per second. The collection was performed using Leica ALS60 MPiA LiDAR systems, serial

numbers 113 and 142.

| Type of Source Media: External hard drive

Fugro EarthData, Inc. utilized commercial software as well as proprietary software for automatic filtering of

LiDAR data to identify and re-classify elevation points falling on vegetation, building, and other above ground structures into

separate data layers. The parameters used in the process were customized for each terrain type to obtain optimum results. Once

the automated filtering was completed, the files were run through a visual inspection to ensure that the filtering was not too

aggressive or not aggressive enough. In cases where the filtering was too aggressive and important terrain features were filtered

out, the data was either run through a different filter or was corrected during the manual filtering process. Interactive editing

was then completed in 3D visualization software which also provides manual and automatic point classification tools using

commercial and proprietary software for the process. Vegetation and artifacts remaining after automatic data post-processing were

reclassified manually through interactive editing. The hard edges of ground features that were automatically filtered out during

the automatic filtering process were brought back into ground class during manual editing. The technician then reviewed the LiDAR

points with color shaded TINs for anomalies in ground class during interactive filtering. Upon the completion of bare earth

filtering and peer review process, the classified LiDAR point cloud work tiles went through a water classification routine based

on the collected water polygons. Upon the completion of finalization of the classified LiDAR point cloud work tiles, the topographic

LiDAR classified point cloud data that was produced under the JALBTCX and NOAA OCM programs was merged. The final classified

LiDAR point data were packaged to NAD83 (NSRS2007), UTM zones 10 and 11 north, meters; NAVD88, meters, using GEOID09 and cut to

the approved tile layout and project boundary in LAS format.

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TerraSurv under contract to Fugro EarthData, Inc. successfully established ground control for Coastal California

LiDAR. A total of 307 ground control points were acquired. GPS was used to establish the control network. The horizontal datum was

the North American Datum of 1983 (NAD83, NSRS2007). The vertical datum was the North American Vertical Datum of 1988 (NAVD88).

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The hydro-enforced bare earth DEM was generated using the bare earth points, as well as the 3D hydro breaklines. The following is

a step-by-step breakdown of the process:

1) After the deliverable LAS files were generated for the entire project area and QC'ed, and the 3D breaklines were collected and

QC'ed, they were used to produce the hydro-enforced bare earth DEM. The bare earth points that fell within 1*NPS along the hydro

breaklines were taken out of from Ground class so that these points were excluded from the DEM generation process. This process

was done in batch mode using Fugro EarthData's proprietary software.

2) Inland ponds and lakes, inland streams and rivers, and tidal water bodies were hydro-flattened within the DEM. Hydro-flattening

was applied to water impoundments, natural or man-made, larger than ~2 acres in area (inland ponds and lakes larger than 1 acre

were collected for the 500 meter corridor); to streams nominally wider than 100' (inland streams and rivers wider than 15 meters

were collected for the 500 meter corridor); and to tidal waters bodies, which includes any significant water body that is

affected by tidal variations.

3) The hydro-flattened bare earth DEM generated in initial grid format was then clipped to the approved DEM product boundary.

4) After the hydro-flattened bare earth DEM was clipped to the boundary, the technician checked the tiles to ensure that the grid

spacing met specifications and checked the surface to ensure proper hydro-flattening. The data was cut to the approved tile

layout. The entire data set was checked for complete project coverage and to ensure it was free of anomalies.

5) The hydro-flattened bare earth DEM was then converted to the delivery ESRI Grid format.