2004 St. Johns County, Florida Lidar
This dataset is the bare earth lidar data for St. Johns County, Florida, acquired
in early January and February of 2004. This data was collected to develop comprehensive
countywide base mapping and perform other GIS enhancements to support master drainage
planning, transportation planning, preliminary engineering and wetland preservation
studies. The surveyed area included all of St. Johns County, approximately 610 square
miles. Eighty-seven (87) flight lines of high density lidar data (average GSD is 3.3
feet) were obtained at an altitude of 3000 feet AGL. This data set contains only model
keypoints (points that are a thinned data set that is intended to remove extraneous
data such as trees and points that are deemed redundant to the final bare earth product)
that are classified as ground points. As a result, there are a lower number of points
than in a full mass point lidar data set; and it is recommended that the data be downloaded
as points and used with a TIN (Triangulated Irregular Network) or similar algorithm
to produce a bare earth surface.
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
St. Johns County Florida GIS
- St. Johns County, Florida Public Works Department
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||The purpose of this topographic lidar survey was to produce a digital terrain model
(DTM) of sufficient density and accuracy to generate 1-foot contours, compile limited
planimetric features and generate panchromatic (black and white) digital orthophoto
||2004-01-17 to 2004-02-07
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- St. Johns County
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
- Woolpert, Inc.
- DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
| Processing Steps
- The LiDAR data was acquired in 93 flight lines acquired in 6 sessions between January
17 and February 7, 2004 from an altitude of 3,000 feet above ground level (AGL) to
provide an average ground sample distance (GSD) of 3.3 feet. Three concurrent airborne
GPS base stations were used for each acquisition session. The ABGPS data were reduced
using the GrafNav software package by Waypoint Consulting, Inc. The IMU data was reduced
using the PosProc software package by Applanix Corporation. The initial lidar "point
cloud" was derived through the ALS Post Processor software package by Leica Geosystems.
The aircraft, lidar system and associated computer hardware and software are owned
and operated by Woolpert LLP. Once the initial lidar "point cloud" was derived, Woolpert
performed QC to look for any systematic error within the lidar flights using proprietary
software. After systematic error was identified and removed, the individual lidar
flights were clipped to remove overlap between adjacent flight lines and provide a
homogeneous coverage over the project extents. Using the homogeneous coverage, above
ground features were classified and removed using proprietary software to produce
the bare-earth coverage.
- The NOAA Coastal Services Center (CSC) received the files in ASCII format. The data
was in Florida State Plane Projection, NAVD88 vertical datum and the vertical units
of measure were feet. CSC performed the following processing to the data to make it
available within Digital Coast: 1. The data were converted from Florida State Plane
East, Zone 0901 coordinates to geographic coordinates. 2. The data were converted
from NAVD88 (orthometric) heights to GRS80 (ellipsoid) heights using Geoid 03. 3.
The vertical unit of measure for the data was converted from feet to meters. 4. The
LAS data were sorted by latitude and the headers were updated.
- The NOAA National Geophysical Data Center (NGDC) received lidar data files via ftp
transfer from the NOAA Coastal Services Center. The data are
currently being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/.
The data can be used to re-populate the system. The data are archived in LAS
or LAZ format. The LAS format is an industry standard for LiDAR data developed by
the American Society of Photogrammetry and Remote Sensing (ASPRS); LAZ is a loseless
compressed version of LAS developed by Martin Isenburg (http://www.laszip.org/). The
data are exclusively in geographic coordinates (either NAD83 or ITRF94). The data
are referenced vertically to the ellipsoid (either GRS80 or ITRF94), allowing for
the ability to apply the most up to date geoid model when transforming to orthometric
Metadata Last Modified: 2013-05-07
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