2006 Southwest Florida Water Management District (SWFWMD) Lidar: Rutland Ranch District

The Light Detection and Ranging (LiDAR) LAS dataset is a survey of select areas within Rutland Ranch. This data falls in Manatee

County. These data were produced for the Southwest Florida Water Management District (SWFWMD). The Rutland Ranch LiDAR Survey project

area consists of approximately 17 square miles. The LiDAR point cloud was flown at a density sufficient to support a maximum final post

spacing of 4 feet for unobscured areas. 3001 Inc. acquired 40 flightlines on February 1, 2006. The data was divided into 5000' by 5000'

foot cells that serve as the tiling scheme. The Rutland Ranch LiDAR Survey was collected under the guidance of a Professional Mapper/

Surveyor.

Original contact information:

Contact Org: Southwest Florida Water Management District

Phone: 352-796-7211

The Southwest Florida Water Management District uses topographic information to support regulatory, land management and

acquisition, planning, engineering, and habitat restoration projects. The Rutland Ranch LiDAR Survey data will support the creation

of Federal Emergency Management Agency Flood Insurance Rate Maps (FEMA FIRM) and an integrated ground and surface water model for

Rutland Ranch. All data will be public record as defined by applicable Florida statutes. The Rutland Ranch LiDAR Survey was collected

under the guidance of a licensed and professional Surveyor/Mapper.

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The metadata are not complete if the format is not compatible with ArcGIS 9, if it is not FGDC Compliant, and

if copies of the survey report in PDF format are not delivered as an attachment. The information in this report is the result of the

LiDAR surveys performed on the dates indicated and the general conditions at the time.

The Rutland Ranch Ground Control Report may be viewed at: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/68/supplemental/index.html

Any conclusions drawn for the analysis of this information are not the responsibility of the Office for Coastal Management or its partners.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer;

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Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this

data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness

of its limitations.

ArcInfo 9.0

Stream shore lines and 2-D coordinate line strings were collected as breaklines using LiDAR that was acquired

and processes to FEMA specifications. These breaklines were created from on-screen digitizing using a combination of the LiDAR points

and the orthophotography. Attributes were verified using routines that verify the vertical and horizontal positions of the breaklines.

All ground control processing and adjustment is performed using published coordinate horizontal

and vertical datums (e.g. NGS CORS). For deliverables, Corpscon for Windows Version 5.11.08 (geoid 99) was used for horizontal and

vertical datum conversion as well as for coordinate system conversion purposes (e.g. UTM to State Plane).

The accuracy assessment was performed using a standard method to compute the root mean square error

(RMSE) based on a comparison of ground control points (GCP) and filtered LiDAR data points. Filtered LiDAR data has had vegetation and

cultural features removed and by analysis represents bare earth elevations. Testing was performed prior to gridding of the filtered

LiDAR data points and construction of the Intergraph .dtm file format. The RMSE figure was used to compute the vertical National

Standard for Spatial Data Accuracy (NSSDA). Ground control was established by 3001, Inc. A spatial proximity analysis was used to select

edited LiDAR data points contiguous to the relevant GCPs. A search radius decision rule is applied with consideration of terrain

complexity, cumulative error and adequate sample size. Cumulative error results from the errors inherent in the various sources of

horizontal measurement. These sources include the airborne GPS, GCPs and the uncertainty of the accuracy of the LiDAR data points.

This accuracy is achieved prior to the sub-sampling that occurs through integration with the inertial measurement unit (IMU) positions

that are recorded. It is unclear at this time whether the initial accuracy is maintained. The horizontal accuracy of the GCPs is

estimated to be in the range of approximately 1 to 1.6 inches. Finally, sample size was considered. The specification for the National

Standard for Spatial Data Accuracy is a minimum of 20 points to conduct a statistically significant accuracy evaluation (Minnesota

Planning, 1999, Positional Accuracy Handbook, Minnesota Planning Land Management Information Center, St. Paul, Minnesota., p.3).

Most statistical texts indicate that a minimum of 30 sample points provide a reasonable Approximation of a normal distribution.

The intent of the NSSDA is to reflect the geographic area of interest and the distribution of error in the data set (Federal Geographic

Data Committee, 1998, Geospatial National Standard for Spatial Data Accuracy, Federal Geographic Data Committee Secretariat, Reston,

Virginia, p.3-4). Additional steps were taken to ensure the vertical accuracy of the LiDAR data including:

Step 1: Precision Bore sighting (Check Edge-matching)

Step 2: Compare the LiDAR data to the Field Survey (Field survey is to FEMA specifications and more stringent internal specifications)

Step 3: Automated Filtering

Step 4: Manual Editing (Quality Control)

Step 5: 3-D digitizing and Photogrammetric Compilation of hydrographic breaklines

RMSE is 0.111 feet which equates to a Vertical Accuracy of 0.218 feet at the 95% confidence level.

Cloud Cover: 0

The LAS files were flown at a density sufficient to support a maximum final post spacing of 4 feet for unobscured areas.

The bare-earth surface will contain voids in areas that were densely vegetated, covered by bridges, buildings, water, fresh asphalt, sand etc.

The LAS files were flown at a density sufficient to support a maximum final post spacing of 4 feet for unobscured

areas. 3001 Inc. acquired 40 flightlines on February 1, 2006. The data was divided into 5000' by 5000' foot cells that serve as the

tiling scheme. The Rutland Ranch LiDAR Survey was collected under the guidance of a Professional Mapper/Surveyor.