2012 Georgia Department of Natural Resources (GADNR) Topographic LiDAR: Pickens, Rockdale and Troup Counties

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This graphic shows the lidar coverage for Pickens County, Rockdale County and Troup County in Georgia.

Date that the source FGDC record was last modified.

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

Partial upload of Positional Accuracy fields only.

Partial upload to move data access links to Distribution Info.

Applanix software was used in the post processing of the

airborne GPS and inertial data that is critical to the positioning

and orientation of the sensor during all flights. POSPac MMS provides

the smoothed best estimate of trajectory (SBET) that is necessary

for Optech's post processor to develop the point cloud from the

LiDAR missions. The point cloud is the mathematical three dimensional

collection of all returns from all laser pulses as determined from

the aerial mission. At this point this data is ready for analysis,

classification, and filtering to generate a bare earth surface model

in which the above ground features are removed from the data set.

The point cloud was manipulated within the Optech or Leica software; GeoCue,

TerraScan, and TerraModeler software was used for the automated

data classification, manual cleanup, and bare earth generation from

this data. Project specific macros were used to classify the ground

and to remove the side overlap between parallel flight lines.

All data was manually reviewed and any remaining artifacts removed

using functionality provided by TerraScan and TerraModeler.

Class 2 LIDAR was 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. Inland Ponds and Lakes of 2 acres or greater were also collected.

Elevation values were assigned to all Inland Ponds and Lakes using TerraModeler functionality.

Elevation values were assigned to all Inland Streams and Rivers using Photo Science proprietary software.

All Class 2 LIDAR data falling inside of the collected breaklines were then classified to Class 9 and Class 2 LIDAR data falling within a

proximity of three feet will be classified to Class 10 using TerraScan macro functionality.

The breakline files were translated to ESRI Shapefile format using ESRI conversion tools.

Data was then run through additional macros to ensure deliverable classification

levels matching LAS ASPRS Classification structure. GeoCue functionality was

used to ensure correct LAS Version. In house software was used as a final

QA/QC check to provide LAS Analysis of the delivered tiles.

Tiles were run through automated scripting

within ArcMap and were combined with the Hydro Flattened Breaklines

to create the 4' DEM. Final DEM tiles were clipped to the tile boundary in order to provide a seamless dataset.

A manual QA review of the tiles was completed in ArcMap and Global Mapper to ensure full coverage with

no gaps or slivers within the project area.

The NOAA Office for Coastal Management (OCM) received topographic files in LAS format. The files contained lidar

elevation and intensity measurements. The data were received in Georgia State Plane West 1002 (NAD83) coordinates

and were vertically referenced to NAVD88 using the Geoid09 model. The vertical units of the data were

feet. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid09.

2. The topographic las files' vertical units were converted from survey feet to meters.

3. The topographic las files were converted from a Projected Coordinate System (GA SPW 1002) to a Geographic Coordinate system (GCS).

4. The topographic las files' horizontal units were converted from survey feet to decimal degrees.