2014 Mobile County, AL Bare Earth DEM

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This graphic shows the lidar coverage in Mobile County Alabama from the 2014 collection.

Date that the source FGDC record was last modified.

Converted from FGDC Content Standard for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

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LiDAR, DEM, Contour | Source Geospatial Form: LAS | Type of Source Media: Portable Hard Drive

Ground Control This Geodetic Control Survey was conducted to support Light Detection and Ranging (LiDAR) data in accordance with the National Digital Elevation Program (NDEP) and the American Society for Photogrammetry and Remote Sensing (ASPRS) guidelines. A GPS control network was performed for the purposes of establishing a three-dimensional coordinates on each of the base station locations. The control network included a combination of a National Geodetic Survey (NGS) Control Monument (MOB AP STA A1), National Geodetic Survey (NGS) CORS (AL84, AL90, AL92, ALDI, ALM) ,Mobile Control Monuments (MCC1062, MCC1067, MCC1070, MCC1072, MCC1073, MOB1000, MOB1008, MOB1009, MOB1011, MOB1023, MOB1031, MOB1034) and a capped iron found (CIPF). GPS observations at all ground control points in the network were made with Leica System 500 dual frequency GPS-receivers w/ Leica AT502 antenna and a NovAtel DL 4=L1L2 receiver w/ NovAtel NOV702 3.00 antenna between April 30, 2014 and May 2, 2014.

Aerial LiDAR Acquisition: Aerial data collection was acquired, in one (9) mission, using the ALS70 SN# 7123 at an altitude of 5500 ft. MSL. This was to support a 2.0 ppm^2 LiDAR point cloud. Airborne GPS and IMU data was collected during the acquisition and supported by Topcon Viper GPS base station that occupied NGS monument MOBARP. Data acquisition was collected January 12th 2014 through January 22th 2014.

LIDAR PROCESSING:

LiDAR Calibration: Initial processing of the GPS data was processed using Inertial Explorer. The solution file was generated and ALSPP software was used to generate georeferenced laser returns which were then processed in strip form allowing for the QC of the overlap between strips (lines). The data from each line were combined and automated classification routines run to determine the initial surface model. This initial surface model was then verified to the LiDAR test points.

LiDAR Classification: The calibrated LiDAR data was run through automated classification routines and then manually checked. The data was classified into the following classes: 1-unclassified, 2-ground, 3-low-points/noise, 9-water

GIS Development Products:

-Hydro-line Collection: Hydro breaklines were compiled using LiDAR Intensity data and surface model of the project area. After the completion of breaklines, they were validated and encoded into the LiDAR surface and used to hydro-enforce/flatten all significant water bodies.

-Terrain Creation: Terrain surface was created using hydro breaklines and bare ground LiDAR.

-ESRI DEM Creation: ESRI DEMs were created from the breaklines and bare-earth (ground) LiDAR data. DEM were created at 2ft resolution and tiled to client Index. Mobile county bare-earth DEM dataset produced from algorithmically thinned bare-earth ground classified lidar point cloud.

The NOAA Office for Coastal Management (OCM) received the files from the City of Mobile GIS office. The files were ingested into the Digital Coast Data Access Viewer (DAV) system and this metadata record was modified to correct errors and reflect distribution through the DAV system.

Data were converted to cloud optimized geotiff format to support streaming. Georeferencing for the vertical was added.