2004 Southwest Florida Water Management District Lidar: Sarasota District

Resource lineage description

source

source description  Source Contribution: Kevin Chappell, a Florida PSM, under contract to EarthData International established 15 photo identifiable ground control after aerial imagery acquisition. The points were surveyed using GPS for both vertical and horizontal coordinate values. Ground control references Florida West State Plane NAD83, NAVD88 both in Meters. Source Type Electronic mail system

representative resolution scale:

Scale denominator: 1200

source citation

Title Report of Survey - SWFWMD, Sarasota County, FL

publication  Date   2004-04-21

presentationForm  documentDigital

cited responsible party - originator

organisation Name  Kevin J. Chappell

source

source description  Source Contribution: The digital aerial photographic mission was composed of a total of 2 lifts of flight lines. Photography was obtained at an altitude of 9,450 feet above mean terrain. Digital photography was recorded in conjunction with airborne GPS; the stationary GPS receiver was positioned over a control point located at the airport. Recorded digital imagery was shipped via external hard drive to the production facility for processing. Source Type Firewire Drive

representative resolution scale:

Scale denominator: 14400

source citation

Title Digital Aerial Photography of Sarasota County, FL

publication  Date   2004-02-08

presentationForm  profileDigital

cited responsible party - originator

organisation Name  EarthData Aviation, LLC

source

source description  Source Contribution: The lidar acquisition for Sarasota County consisted of 2 lifts of flight lines acquired in 2 sorties using the Leica ALS40 sensor. The data was acquired at a flying height of 6,000 feet AMT with a scan rate of 13 Hz and a 25 degree field of view. Approximately 3.04 billion raw lidar points were collected at a nominal 2 meter post spacing. Source Type Firewire Drive

source citation

Title Lidar Acquisition of Sarasota County, FL

publication  Date   2004-03-04

presentationForm  profileDigital

cited responsible party - originator

organisation Name  EarthData Aviation

AbsoluteExternalPositionalAccuracy

name Of Measure Horizontal Positional Accuracy Report

evaluation Method Description  The digital orthophotos fully comply with NMAS standards for production of orthophotos at a horizontal natural ratio of 1 to 2,400 with a ground pixel resolution of 1 foot. Tested 1.1 m (3.6-feet) horizontal accuracy at the 95% confidence level.

AbsoluteExternalPositionalAccuracy

name Of Measure Vertical Positional Accuracy Report

evaluation Method Description  The digital elevation model is fully compliant with National Standard for Spatial Data Accuracy (NSSDA) published by the Federal Geographic Data Committee (FGDC) in 1998. The NSSDA uses root-mean-square error (RMSE) to estimate positional accuracy. RMSE is the square root of the average of the set of squared differences between data set coordinate values and coordinate values from an independent source of higher accuracy for identical points. Accuracy is reported in ground distances at the 95% confidence level. Accuracy reported at the 95% confidence level means that 95% of the positions in the data set will have an error with respect to true ground position that is equal to or smaller than the reported accuracy value. The reported accuracy value reflects all uncertainties, including those introduced by geodetic control coordinates, compilation, and final computation of ground coordinate values in the product. The intended vertical accuracy of this project is 17.98 cm (0.59-feet) (95% confidence level) vertical. RMSE=9.144 cm (0.3-feet) for unobscured ground points, not tested.

Completeness Commission

evaluation Method Description  The following software is used for validation of the 1. Aerotriangulation - ISTAR Processing 2. DTM data - Z/I Imaging SSK 3. Digital Orthophotography - Z/I Imaging OrthoPro

Completeness Omission

evaluation Method Description  The following software is used for validation of the 1. Aerotriangulation - ISTAR Processing 2. DTM data - Z/I Imaging SSK 3. Digital Orthophotography - Z/I Imaging OrthoPro

ConceptualConsistency

measure Description  Compliance with the accuracy standard was ensured by the placement of GPS ground control prior to the acquisition of aerial photography. The following checks were performed. 1. The ground control and airborne GPS data stream were validated through a fully analytical bundle aerotriangulation adjustment. The residuals of the adjustment met the required standards for accuracy which are 1 part in 10,000 of the flying height for the horizontal position (X and Y) and 1 part in 9,000 or better of the flying height in elevation (Z). 2. The DTM (Digital Terrain Model) data were checked against the project control. The technician visited and confirmed the accuracy of the project mass points during initial processing. 3. Digital orthophotography was validated through an inspection of edge matching and visual inspection for image quality.