Slide Menu
Search Help Show/Hide Menu
Short Citation:
OCM Partners, 2024: 2011 Worcester County - VA FEMA LiDAR,

Item Identification

Title: 2011 Worcester County - VA FEMA LiDAR
Short Name: 2011 Coastal Worcester
Status: Completed
Publication Date: 2018

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 Worcester County. The nominal pulse spacing for this project is 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 263 tiles (6000 ft x 4000 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 ft cell size hydro flattened Digital Elevation Models (DEM).


Obtained by NOAA from the Maryland iMAP system (


Theme Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Science Keywords
ISO 19115 Topic Category
None bare earth
None bare ground
None high-resolution
None Light Detection and Ranging

Spatial Keywords

Thesaurus Keyword
Geographic Names Information System Maryland

Physical Location

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

Data Set Information

Data Set Scope Code: Data Set
Data Set Type: GIS Files
Maintenance Frequency: As Needed
Data Presentation Form: Map (digital)
Entity Attribute Overview:

Lidar point cloud x,y,z and intensity data with classification scheme: 1-Unclassified, 2-Ground, 7-Noise, 9-Water, 10-Ignored Ground due to breakline proximity, and 11-Withheld.

Distribution Liability:

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

Data Set Credit: Dewberry, FEMA

Support Roles

Data Steward

CC ID: 729480
Date Effective From: 2018-02-26
Date Effective To:
Contact (Person): Waters, Kirk
Address: 2234 South Hobson Ave
Charleston, SC 29405
Email Address:
URL: NOAA OCM homepage


CC ID: 729479
Date Effective From: 2018-02-26
Date Effective To:
Contact (Organization): Office for Coastal Management (OCM)
Address: 2234 South Hobson Avenue
Charleston, SC 29405-2413

Metadata Contact

CC ID: 729481
Date Effective From: 2018-02-26
Date Effective To:
Contact (Person): Waters, Kirk
Address: 2234 South Hobson Ave
Charleston, SC 29405
Email Address:
URL: NOAA OCM homepage

Point of Contact

CC ID: 729482
Date Effective From: 2018-02-26
Date Effective To:
Contact (Person): Waters, Kirk
Address: 2234 South Hobson Ave
Charleston, SC 29405
Email Address:
URL: NOAA OCM homepage


Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1140750
W° Bound: -75.306562
E° Bound: -75.047219
N° Bound: 38.4528449
S° Bound: 38.024069

Coastal Worcester Maryland

Extent Group 1 / Time Frame 1

CC ID: 1140749
Time Frame Type: Range
Start: 2011-03-05
End: 2011-07-29

Acquisition dates for the lidar collection

Spatial Information

Spatial Resolution

Horizontal Distance: 0.5 Meter

Spatial Representation

Representations Used

Vector: Yes

Vector Representation 1

CC ID: 729489
Point Object Present?: Yes
Point Object Count: 1478659827

Access Information

Security Class: Unclassified
Data Access Procedure:

Access via online tool

Data Access Constraints:


Data Use Constraints:

This data was produced for the USGS and FEMA according to specific project requirements. This information is provided "as is". Further documentation of this data can be obtained by contacting: Patrick Emmett, MS 666, 1400 Independence Road, Rolla, MO 65401. Telephone (573) 308-3587.

Distribution Information

Distribution 1

CC ID: 729483
Start Date: 2018-03-14
End Date: Present
Download URL:
Distributor: Office for Coastal Management (OCM) (2018-02-26 - Present)

Customizable download of point cloud data and derived products.

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



CC ID: 729484
Name: Digital Coast
URL Type:
Online Resource


CC ID: 729485
Name: Maryland iMAP
URL Type:
Online Resource

Location of the originating point clouds.

Data Quality

Horizontal Positional Accuracy:

Not tested. Expected to be less than 1 meter at 95% confidence level.

Vertical Positional Accuracy:

The vertical accuracy of the LiDAR was tested by Dewberry with 60 independently collected checkpoints. The survey checkpoints are evenly distributed throughout the project area and cover the three major land cover classifications.

All 60 checkpoints were used to compute the Fundamental Vertical Accuracy (FVA). Project specifications required a FVA of 0.60 ft (18 cm) based on a RMSEz 0.31 ft (9.25 cm) x 1.9600. All checkpoints were also used to compute the Consolidated Vertical Accuracy (CVA). Project specifications required a CVA of 1.19ft (36.3 cm) based on the 95th percentile. The dataset for the Worcester County project satisfies the criteria for FVA:

Lidar dataset tested 0.43 ft vertical accuracy at 95% confidence level, based on RMSEz (0.22 ft) x 1.9600.

Based on the vertical accuracy testing conducted by Dewberry, using NDEP and ASPRS methodology, consolidated vertical accuracy at the 95% confidence level is computed using the 95th percentile method. The dataset for the Worcester County project satisfies the criteria:

Lidar dataset tested 0.90 ft vertical accuracy at 95% confidence level in all land cover categories combined.

Data Management

Have Resources for Management of these Data Been Identified?: Yes
Approximate Percentage of Budget for these Data Devoted to Data Management: Unknown
Do these Data Comply with the Data Access Directive?: Yes
Is Access to the Data Limited Based on an Approved Waiver?: No
Actual or Planned Long-Term Data Archive Location: NCEI-CO


Lineage Statement:

Original acquisition and processing of lidar data was completed by Terrapoint and Dewberry. It was delivered to FEMA, USGS, and Maryland. NOAA OCM obtained the data from Maryland iMAP and modified for ingest into the Digital Coast system.


Lidar data from Maryland iMAP

CC ID: 1140739
Extent Type: Range
Extent Start Date/Time: 2011-02-06
Extent End Date/Time: 2011-02-16
Citation URL:
Source Contribution:

Point cloud data repository for Maryland

Process Steps

Process Step 1

CC ID: 1140740

Establishment of survey points to support the LiDAR data collection. Two existing published NGS stations (AI7609, HU2327) were observed in a GPS control network and used to establish four new points for the primary control for this site. 1110312 was 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) Worcester, 1110312, N38 18 22.12367, W75 07 40.46389, -33.7921, 2.2581

Process Date/Time: 2011-03-01 00:00:00

Process Step 2

CC ID: 1140741

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: 2011-03-01 00:00:00

Process Step 3

CC ID: 1140742

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: 2011-04-01 00:00:00

Process Step 4

CC ID: 1140743

Dewberry utilizes a variety of software suites for inventory management, classification, and data processing. All LiDAR related processes begin by importing the data into the GeoCue task management software. GeoCue allows the data to retain its delivered tiling scheme (6000 ft by 4000 ft). The tiled data is then opened in Terrascan where Dewberry uses proprietary ground classification routines to remove any non-ground points and generate an accurate ground surface. The ground routine consists of three main parameters (building size, iteration angle, and iteration distance); by adjusting these parameters and running several iterations of this routine an initial ground surface is developed. The building size parameter sets a roaming window size. Each tile is loaded with neighboring points from adjacent tiles and the routine classifies the data section by section based on this roaming window size. The second most important parameter is the maximum terrain angle, which sets the highest allowed terrain angle within the model. Once the ground routine has been completed a manual quality control routine is done using hillshades, cross-sections, and profiles within the Terrasolid software suite. After this QC step, a peer review and supervisor manual inspection is completed on a percentage of the classified tiles based on the project size and variability of the terrain. After the ground classification corrections were completed, the dataset was processed through a water classification routine that utilizes breaklines compiled by Dewberry to automatically classify hydrographic features. The water classification routine selects ground points within the breakline polygons and automatically classifies them as class 9, water. During this water classification routine, points which are in close proximity (1 m) to the hydrographic features are moved to class 10, an ignored ground. In addition to classes 1, 2, 8, 9, and 10, the project allows for a Class 7, noise points. This class was only used if needed when points could manually be identified as low/high points. Dewberry also used Class 11 - Withheld points.

The fully classified dataset is then processed through Dewberry's comprehensive quality control program.

The data was classified as follows:

Class 1 = Unclassified. This class includes vegetation, buildings, noise etc.

Class 2 = Ground

Class 7= Noise

Class 8= Model Key Points

Class 9 = Water

Class 10= Ignored Ground

Class 11= Withheld

The LAS header information was verified to contain the following:

Class (Integer)

GPS Week Time (0.0001 seconds)

Easting (0.01 ft)

Northing (0.01 ft)

Elevation (0.01 ft)

Echo Number (Integer 1 to 4)

Echo (Integer 1 to 4)

Intensity (8 bit integer)

Flight Line (Integer)

Scan Angle (Integer degree)

Process Date/Time: 2011-11-01 00:00:00

Process Step 6

CC ID: 1140744

Deliverable Product Generation Raw Lidar point were reprojected from UTM zone 18 to the delivery projection State Plane Maryland, 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 0.01m) 4. Northing (reported to the nearest 0.01m) 5. Elevation (reported to the nearest 0.01m) 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 3 degrees of the swath - 1 file per swath, 1 swath per file (except when swath had to be divided in section for size or calibration).

Process Step 7

CC ID: 1140745

NOAA OCM downloaded the data from Maryland iMAP as zip files by Block.

Process Date/Time: 2017-10-16 00:00:00
Process Contact: Office for Coastal Management (OCM)
Source: Lidar data from Maryland iMAP

Process Step 8

CC ID: 1140746

Lidar data were changed from NAVD88 (Geoid09) vertical coordinates to ellipsoid heights using the GEOID09 grids. Horizontal coordinates were changed to geographic NAD83(NSRS2007)

Data were then ingested into the Digital Coast Data Access Viewer system for distribution.

Process Date/Time: 2018-02-26 00:00:00
Process Contact: Office for Coastal Management (OCM)

Acquisition Information


Instrument 1

CC ID: 1140747
Identifier: Leica ALS60
Instrument / Gear: Instrument
Instrument Type: lidar

Multipulse in air lidar sensor

Catalog Details

Catalog Item ID: 51657
GUID: gov.noaa.nmfs.inport:51657
Metadata Record Created By: Kirk Waters
Metadata Record Created: 2018-02-27 15:43+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2024-01-26 18:33+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