Dataset Identification:
- Dewberry collected LiDAR for ~3,341 square miles in various Virginia Counties, a part of Worcester County, and Hoopers Island. The acquisition was performed by Terrapoint. This metadata covers the LiDAR produced for the Middle Counties project area. The nominal pulse spacing for this project is 1.6 ft (0.5 meters). This project was collected with a sensor which collects intensity values for each discrete pulse extracted from the waveform. GPS Week Time, Intensity, Flightline and echo number attributes were provided for each LiDAR point. Dewberry used proprietary procedures to classify the LAS according to contract specifications: 1-Unclassified, 2-Ground, 7-Noise, 9-Water, 10-Ignored Ground due to breakline proximity, and 11-Withheld. Dewberry produced 3D breaklines and combined these with the final LiDAR data to produce seamless hydro flattened DEMs for the 918 tiles (5000 ft x 5000 ft) that cover the project area.
- Title 2012 FEMA Lidar: Middle Counties (VA)
- publication Date 2015-01-12
- organisation Name NOAA Office for Coastal Management (OCM)
- Contact information
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- Address
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- , Charleston, SC
- organisation Name Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Office for Coastal Management (OCM)
- organisation Name VA FEMA LiDAR
- organisation Name
- Contact information
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- Linkage for online resource
- organisation Name
- Contact information
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- Linkage for online resource
- organisation Name
- Contact information
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- Linkage for online resource
- organisation Name
- Contact information
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- Linkage for online resource
Theme keywords (theme):
DTM
Elevation
Lidar
LAS
DEM
Breaklines
- Title None
Location keywords:
Virginia
Charles City County
New Kent County
Prince George County
- Title None
Temporal keywords:
2011
May
- Title none
purpose:
Browse image (thumbnail):
- maintenance or update frequency: asNeeded
- Constraints
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- Use limitation statement:
- Any conclusions drawn from the analysis of this information are not the responsibility of USGS, FEMA, Dewberry, NOAA, the Office for Coastal Management or its partners.
- Legal Constraints
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- use constraint: otherRestrictions
- Other constraints
- Use Constraints: 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. These data depict the heights at the time of the survey and are only accurate for that time.
- Legal Constraints
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- Access Constraints otherRestrictions
- Other constraints
- Access Constraints: None
Resource extent
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- westBoundLongitude -77.401043
- eastBoundLongitude -76.754699
- northBoundLatitude 37.627710
- southBoundLatitude 37.36991635
Geographic Bounding Box - Temporal Extent
Geographic Extent
2011-05-06
2012-04-02
- A footprint of this data set may be viewed in Google Earth at: ftp://coast.noaa.gov/pub/DigitalCoast/lidar1_z/geoid12a/data/4710/supplemental/va2012_usgs_fema_middleco_m4710.kmz A report for this dataset is available at: ftp://coast.noaa.gov/pub/DigitalCoast/lidar1_z/geoid12a/data/4710/supplemental/va2012_usgs_fema_middleco_m4710_surveyreport.pdf
Content information: feature catalog description
- Included With Dataset
Data quality information
Scope of quality information
- name Of Measure Horizontal Positional Accuracy Report
- evaluation Method Description Lidar source compiled to meet 1.158 meters horizontal RMSE.
- name Of Measure Horizontal Positional Accuracy
- measure Description Dewberry does not perform independent horizontal accuracy testing on the LiDAR. LiDAR vendors perform calibrations on the LiDAR sensor and compare data to adjoing flight lines to ensure LiDAR meets the 115 cm horizontal accuracy standard at the 95% confidence level. Please see the final project report for more details.
- Quantitative Result
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- result value 1.158
- value Units
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- name Of Measure Vertical Positional Accuracy Report
- evaluation Method Description The vertical accuracy of the LiDAR was tested by Dewberry with 36 independently collected checkpoints. The survey checkpoints are distributed throughout the project area. These 36 checkpoints contain 11 open terrain points, 13 crops/weeds points, and 12 forested points. The 36 checkpoints were used to compute the Fundamental Vertical Accuracy (FVA) and the Consolidated Vertical Accuracy (CVA). Project specifications required a FVA of 0.183 meters for open terrain and a CVA of 0.364 meters. Appendix A, Guidance for Aerial Mapping and Surveying, to FEMAs Guidelines and Specifications for Flood Hazard Mapping Partners requires a minimum of 60 test points -- 20 each in a minimum of three land cover categories representative of the floodplain. FEMAs Procedure Memorandum No. 61 - Standards for Lidar and Other High Quality Digital Topography -- specifies that the positional accuracy of LiDAR shall be in accordance with ASPRS/NDEP standards for accuracy testing as well as the USGS Lidar Guidelines and Base Specifications, v13. All of these standards and guidelines require testing for Fundamental Vertical Accuracy (FVA), Supplemental Vertical Accuracy (SVA), and Consolidated Vertical Accuracy (CVA), using a minimum of 20 checkpoints each in a minimum of three land cover categories for a minimum total of 60 QA/QC checkpoints. Although tentative tests are performed on smaller subareas with fewer than 20 QA/QC checkpoints, Dewberrys final results will not be official until all areas are merged for testing of the total area with all project checkpoints.
- name Of Measure Vertical Positional Accuracy
- measure Description This RMSE analysis was performed on the Classified LiDAR Data. Based on the vertical accuracy testing conducted by Dewberry, using NSSDA and FEMA methodology, vertical accuracy at the 95% confidence level (called Accuracyz) is computed by the formula RMSEz x 1.9600. The dataset for the Middle Counties project area satisfies the criteria: Lidar dataset tested 0.158 m vertical accuracy at 95% confidence level, based on RMSEz (0.079 m) x 1.9600. The Consolidated Vertical Acccuracy is 0.186 meters.
- Quantitative Result
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- result value 0.079
- value Units
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- evaluation Method Description A visual qualitative assessment was performed to ensure data completeness and bare earth data cleanliness. No void or missing data, the bare earth surface is of good quality and data passes vertical accuracy specifications.
- measure Description Data covers the tile scheme provided for the project area.
Resource distribution information
Distributor
- organisation Name NOAA Office for Coastal Management
- Contact information
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- Telephone
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- Voice 843-740-1202
- Address
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- 2234 South Hobson Ave., Charleston, SC, 29405-2413
- electronic Mail Address coastal.info@noaa.gov
- maintenance or update frequency: annually
- notes: This metadata was automatically generated from the FGDC Content Standards for Digital Geospatial Metadata standard (version FGDC-STD-001-1998) using the 2015-05-04 version of the FGDC RSE to ISO 19115-2 transform.
- notes: Translated from FGDC 2015-06-11T11:44:22.689-04:00
- organisation Name NOAA Office for Coastal Management
- Contact information
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- Telephone
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- Voice 843-740-1202
- Address
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- 2234 South Hobson Ave., Charleston, SC, 29405-2413
- electronic Mail Address coastal.info@noaa.gov