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Short Citation:
OCM Partners, 2023: 2011 USGS-FEMA Lidar: King William County (VA),

Item Identification

Title: 2011 USGS-FEMA Lidar: King William County (VA)
Short Name: va2011_usgs_fema_kingwilliam_m4726_metadata
Status: Completed
Publication Date: 2014-12

Dewberry collected LiDAR for ~3,341 square miles in various Virginia Counties, a part of Worcester County, and Hooper's Island. The acquisition was performed by Terrapoint. This metadata covers the LiDAR produced for the King William 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 (reclassified by OCM to Class 15). Dewberry produced 3D breaklines and combined these with the final LiDAR data to produce seamless hydro flattened DEMs for the 415 tiles (5000 ft x 5000 ft) that cover the project area.


The purpose of this LiDAR data was to produce high accuracy 3D elevation products, including tiled LiDAR in LAS 1.2 format, 3D breaklines, and a 2.5 ft cell size hydro flattened Digital Elevation Models (DEM).



Supplemental Information:

A footprint of this data set may be viewed in Google Earth at:

A report for this dataset is available at:


Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category

Physical Location

Organization: Office for Coastal Management
City: Charleston
State/Province: SC

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: As Needed
Data Presentation Form: las
Entity Attribute Overview:

Lidar points in LAZ format (Classes 1,2,7,9,10,15)

Entity Attribute Detail Citation:


Distribution Liability:

Any conclusions drawn from the analysis of this information are not the responsibility of USGS, FEMA, NOAA, the Office for Coastal Management or its partners.

Support Roles

Data Steward

CC ID: 691428
Date Effective From: 2014-12
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


CC ID: 691430
Date Effective From: 2014-12
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Metadata Contact

CC ID: 691431
Date Effective From: 2014-12
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Point of Contact

CC ID: 691429
Date Effective From: 2014-12
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1136177
W° Bound: -77.370438879
E° Bound: -76.716798791
N° Bound: 37.919034743
S° Bound: 37.510110491

Extent Group 1 / Time Frame 1

CC ID: 1136176
Time Frame Type: Range
Start: 2011-04-19
End: 2011-10-27

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Access Information

Security Class: Unclassified
Data Access Procedure:

This data can be obtained on-line at the following URL:;

Data Access Constraints:


Data 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.

Distribution Information

Distribution 1

CC ID: 743162
Start Date: 2014
End Date: Present
Download URL:
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2014-12 - Present)
File Name: Customized Download

Create custom data files by choosing data area, product type, map projection, file format, datum, etc.

File Type (Deprecated): Zip
Compression: Zip

Distribution 2

CC ID: 743163
Start Date: 2014
End Date: Present
Download URL:
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2014-12 - Present)
File Name: Bulk Download

Simple download of data files.

File Type (Deprecated): LAZ
Distribution Format: LAS/LAZ - LASer
Compression: Zip



CC ID: 743167
Name: Browse Graphic
URL Type:
Browse Graphic
File Resource Format: kmz

This graphic shows the coverage of the 2011 USGS/FEMA Virginia King William County lidar collection.

Activity Log

Activity Log 1

CC ID: 691445
Activity Date/Time: 2016-05-23

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 691444
Activity Date/Time: 2017-11-14

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

Activity Log 3

CC ID: 718730
Activity Date/Time: 2018-02-08

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 743164
Activity Date/Time: 2018-03-13

Partial upload to move data access links to Distribution Info.

Data Quality


These data are not attributed.

Horizontal Positional Accuracy:

Lidar source compiled to meet 1.0 meter horizontal RMSE.; Quantitative Value: 1.0 meters, Test that produced the value: 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 1.0 meter horizontal accuracy standard at the 95% confidence level. Please see the final project report for more details.

Vertical Positional Accuracy:

The vertical accuracy of the Raw Swath LiDAR was tested by Dewberry using 4 open terrain points contained within the project boundary. These 4 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.; Quantitative Value: 0.027 meters, Test that produced the value: This RMSE analysis was performed against the raw, unclassified Swath LAS. 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 South Counties project area satisfies the criteria: Lidar dataset tested 0.079 meters vertical accuracy at 95% confidence level, based on RMSEz (0.027 m) x 1.9600. The Consolidated Vertical Acccuracy is 0.119 meters.

Completeness Report:

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.

Conceptual Consistency:

Data covers the tile scheme provided for the project area.



Classified lidar data

CC ID: 1136167
Contact Role Type: Originator
Contact Type: Organization
Contact Name: USGS

Process Steps

Process Step 1

CC ID: 1136168

Establishment of survey points to support the LiDAR data collection. two existing published NGS stations (FX5374, FX5377) were observed in a GPS control network and used to establish one new point for the primary control for this site. FX5374, FX5377, 239DEB05 were observed and used to control all flight missions and static ground surveys. The following are the final coordinates of the control points used for this project: SurveyBlock, Station, Latitude(D M S Hem), Longitude(D M S Hem), H-Ell(m), H-MSL(m) Counties South, 239DEB05, 36 50 47.15799, -76 59 00.22918, -14.6087, 20.3903 Counties South, FX5374, 36 48 32.84206, -76 37 15.00850, -28.4893, 7.6452 Counties South, FX5377, 36 41 06.67117, -77 06 58.40345, -7.2248, 27.6380

Process Date/Time: 2012-01-01 00:00:00

Process Step 2

CC ID: 1136169

Airborne acquisition of Lidar GeoDigital used one Optech ALTM 3100EA system to collect the data. The Optech System was configured in the following method: Aircraft Speed 150 knots Data Acquisition Height 950 m AGL Swath Width 691.54 m Distance between Flight Lines 300.00 m Overlap 55 % Scanner Field Of View 22 +/- degrees (+/-2 degrees flagged as withheld) Pulse Repetition Rate 70 KHz Scan Frequency 40 Hz Number of Returns per Pulse 4 Discrete returns Beam Divergence 0.3 mRad Flight Line Length shorter than 70km Base Station Distance shorter than 40km Resultant Raw Point Density ~2 pt/m2 with overlap Aircraft platforms were used in the collection of this project: A Cessna 310 aircraft was used to conduct the aerial survey. The Cessna 310 is a fixed wing aircraft that have an endurance of approximately 5 hours. -GPS-IMU: High accuracy IMU (200Hz) and GPS information (1Hz) concerning the attitude and position of the sensor were acquired at the same time as the Laser data. Ground based GPS stations also acquired consecutive GPS information for the duration of the flights. A combination of Sokkia GSR 2600 and NovAtel DL-4+ dual-frequency GPS receivers were used to support the airborne operations of this survey. - Flights and Flight Lines The area is covered by several missions, a mission is defined as the block of acquisition between aircraft take-off and landing flown under good meteorological and GPS conditions, and each mission includes multiple flightlines. Number Of Missions: 18 List Of Missions: o112005a o112006a o112006b o112007a o112007b o112008a o112008b o112010a o112010b o112012a o112013a o112014a o112014b o112015a o112015b o112016a o112016b o112018a Number Of Flight Lines: 219

Process Date/Time: 2012-01-01 00:00:00

Process Step 3

CC ID: 1136170

- Airborne GPS Kinematic processing

Airborne GPS kinematic data was processed on-site using GrafNav kinematic On-The-Fly (OTF) software. Flights were flown with a minimum of 6 satellites in view (13o above the horizon) and with a PDOP of better than 4. Distances from base station to aircraft were kept to a maximum of 40 km, to ensure a strong OTF (On-The-Fly) solution. For all flights, the GPS data can be classified as excellent, with GPS residuals of 3cm average but no larger than 10 cm being recorded.

The Geoid09 geoid model, published by the NGS, was used to transform all ellipsoidal heights to orthometric.

Process Date/Time: 2012-01-01 00:00:00

Process Step 4

CC ID: 1136171

- Generation and Calibration of laser points

Laser data points are generated using Optech's software Dashmap. Those software combine the raw laser range and angle data file with the finalized GPS/IMU trajectory information.

Each mission is evaluated in Terrasolid's Terramatch software to correct any residual roll pitch heading misalignments, if necessary those values are to the data.

The resulting point cloud is projected into the desired coordinate system and created in LAS format. One file per swath, files bigger than 2Gb split in 2.

On a project level, a coverage check is carried out to ensure no slivers are present.

Process Date/Time: 2012-01-01 00:00:00

Process Step 5

CC ID: 1136172

- Mission to mission adjustments of Lidar data

All missions are validated and adjusted against the adjoining

missions for relative vertical biases and collected GPS static and kinematic

ground truthing points for absolute vertical accuracy purposes.

Process Date/Time: 2012-01-01 00:00:00

Process Step 6

CC ID: 1136173

-Deliverable Product Generation

Raw Lidar point are projected were reprojected from UTM zone 18 to the delivery projection State Plane Virginia, US Survey Feet.

*Raw Calibrated LIDAR Point Cloud

Raw LiDAR point cloud, was provided in the following formats/parameters:

- LAS V1.2, point record format 1, Adjusted GPS time, georeferencing information populated in header

- The following fields are included in the LAS file:

1. Adjusted GPS time reported to the nearest microsecond

2. Flight line ID

3. Easting (reported to the nearest 0.01ft)

4. Northing (reported to the nearest 0.01ft)

5. Elevation (reported to the nearest 0.01ft)

6. intensity

7. Echo number

8. Classification

9. Scan angle

10. Edge of scan

11. Scan direction

- Full swaths, all collected points delivered (except discarded flightline)

- The Withheld bit flags the last 2 degrees of the swath (Additional areas are classified with the withheld in areas where wind or vegetation affected the quality of the data long the edge of the flight line. The classification of the additional withheld areas does not affect the density of the data.)

- 1 file per swath, 1 swath per file (except when swath had to be divided in section for size or calibration)

Process Date/Time: 2012-01-01 00:00:00

Process Step 7

CC ID: 1136174

The NOAA Office for Coastal Management (OCM) received the topographic lidar files in LAZ format. The files contained lidar easting, northing, elevation, intensity, return number, etc. The data was received in Virginia State Plane South 4502 (US ft) and NAVD88 (US ft). OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. The files were reviewed and erroneous elevations were removed.

2. Class 11 points (Withheld) were reclassified to Class 15.

3. Data were transformed to Geographic coordinates and ellipsoid heights. The GEOID09 model was removed.

Process Date/Time: 2014-11-07 00:00:00
Process Contact: NOAA Office for Coastal Management (NOAA/OCM)
Phone (Voice): (843) 740-1202
Email Address:
Source: Classified lidar data

Catalog Details

Catalog Item ID: 50125
GUID: gov.noaa.nmfs.inport:50125
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-15 15:24+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2023-10-17 16:12+0000
Metadata Record Published: 2022-03-16
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-03-16
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-03-16