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OCM Partners, 2024: 2005 Maryland Department of Natural Resources LiDAR: Cecil County,

Item Identification

Title: 2005 Maryland Department of Natural Resources LiDAR: Cecil County
Short Name: md2005_m32_metadata
Status: Completed
Publication Date: 2005-01-20

Light Detection and Ranging (LIDAR) is a method of locating objects on the ground using aerial-borne equipment. It is

similar to RADAR or SONAR in that the two-way travel time of an energy beam reflected off an object is precisely measured, but

this technology uses laser light instead of radio or sound waves. This technology has proven very useful in remote sensing of the

earth. It can be used for determining elevations of both the earth's surface and items (natural and man-made) on the surface.

Analysis of LIDAR data is used in detailed modeling of the earth's surface for drainage and floodplain studies, determining how

a new structure will affect views from various locations, shoreline erosion studies, and other reasons. This data set contains

only the bare earth mass points. Bare earth points represent ground features. Features that are above ground, such as buildings,

bridges, tree tops, etc, have been eliminated. Mass points may appear to have "holes" with no elevation values in areas where the

surface could not be determined, such as very dense forests or urban areas.

Original contact information:

Contact Name: Ken Miller

Contact Org: Maryland Department of Natural Resources

Title: Chief. Watershed Information Services Division

Phone: 410-260-8751



The LIDAR-derived data were collected by the Maryland Department of Natural Resources in support of shore erosion studies

along the shorelines of the Chesapeake Bay. It also supports the Federal Emergency Management Agency's specifications for mapping

floodplains. These efforts required detailed elevation data and models, such as those available from LIDAR sensing. The data have

also been made available to aid in other projects that require detailed surface, vegetation and/or structure elevations.



Other Citation Details:

1. Airborne1, Inc. (flight firm)

2. Computational Consulting Services, LLC (processing firm)

3. Spatial Systems Associates, Inc. (post-processing firm)

4. Dewberry and Davis (QA/QC firm)

Supplemental Information:

These data are part of a suite of spatial data products generated using the LIDAR technology. First and

Last returns are generated. From these data, Bare-Earth Mass Points that represent the earths surface are produced. A gridded

Digital Elevation Model (DEM) is produced from the Bare Earth Mass Points. Imagery is also created that represents the intensity

of the LIDAR return; it is a 1-meter resolution product that resembles a panchromatic Digital Orthophoto Quad (DOQ).

The Cecil County, Maryland QA Report may be viewed at:


Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category
DNR General Bald earth
DNR General Bare earth
DNR General Bathymetry/Topography
DNR General DEM
DNR General Digital Elevation Model
DNR General DNR
DNR General Elevation and derived products
DNR General Elevation model
DNR General First return
DNR General Gridded DEM
DNR General Last return
DNR General Surface model
DNR General Terrain model

Physical Location

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

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: None Planned
Distribution Liability:

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the OCM or

its partners.

Data Set Credit: Spatial Systems Associates, Inc. was the prime contractor for this project. It partnered with Airborne1, Inc., Computational Consulting Services, Inc., NXL Construction Services, Inc and Dewberry LLC.

Support Roles

Data Steward

CC ID: 676987
Date Effective From: 2005-01-20
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: 676989
Date Effective From: 2005-01-20
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: 676990
Date Effective From: 2005-01-20
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: 676988
Date Effective From: 2005-01-20
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: 1135347
W° Bound: -76.24904
E° Bound: -75.75024
N° Bound: 39.728895
S° Bound: 39.357195

Extent Group 1 / Time Frame 1

CC ID: 1135346
Time Frame Type: Range
Start: 2005-04-15
End: 2005-04-23

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Access Information

Security Class: Unclassified
Data Access Procedure:

This data set can be obtained online 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. The Department of Natural Resources makes no warranty, expressed or implied, as to the use or

appropriateness of Spatial Data, and there are no warranties of merchantability or fitness for a particular purpose or use. The

information contained in Spatial Data is from publicly available sources, but no representation is made as to the accuracy or

completeness of Spatial Data. The Department of Natural Resources shall not be subject to liability for human error, error due

to software conversion, defect, or failure of machines, or any material used in the connection with the machines, including tapes,

disks, CD-ROMs or DVD-ROMs and energy. The Department of Natural Resources shall not be liable for any lost profits, consequential

damages, or claims against the Department of Natural Resources by third parties. The liability of the Department of Natural Resources

for damage regardless of the form of the action shall not exceed any distribution fees that may have been paid in obtaining Spatial


Distribution Information

Distribution 1

CC ID: 741315
Download URL:
File Name: Customized Download

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

Distribution 2

CC ID: 741316
Download URL:
File Name: Bulk Download

Simple download of data files.

Activity Log

Activity Log 1

CC ID: 677014
Activity Date/Time: 2016-05-23

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 677013
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: 718352
Activity Date/Time: 2018-02-08

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 741317
Activity Date/Time: 2018-03-13

Partial upload to move data access links to Distribution Info.

Technical Environment


A variety of specialized hardware and software platforms were used to collect, process and quality assess

these data. Typically, Intel machines running Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4.

Data Quality


There are four (4) attributes in the Bare Earth Mass Points files, representing the horizontal coordinates

(easting and northing) and vertical position observed and vertical assigned (see process description). Random inspections were made

to assure that each line in the file contained 4 values.

Horizontal Positional Accuracy:

The horizontal coordinate values were designed to meet NSSDA accuracy for data at 1:2400 scale.

Vertical Positional Accuracy:

The RMSE value of 9.3 cm at the 95% confidence level was determined by an independent accuracy

assessment conducted by Dewberry LLC according to the contract specifications. These specifications followed FEMA Appendix A

guidelines regarding assessing vertical accuracy. For data accurate to within 18.5 cm RMSE, the guidelines recommended a minimum

of 20 independent check points be located in each of 5 different land cover categories: Grass/Ground, High Grass/Crops, Brush/Low

Trees, Forest, and Urban/Pavement. A total of 100 points were used for the assessments. These points were surveyed by a licensed

land surveyor and provided a positional location and elevation with an accuracy that exceeded the predicted accuracy of the LIDAR

data. The entire accuracy reports can be found at

; Quantitative Value: 9.3 meters, Test that produced the value:

The RMSE value is 9.3 cm. See the Vertical Positional Accuracy Report section for more


Completeness Measure:

Cloud Cover: 0

Completeness Report:

Spatial Systems Associates performed various inspections of the data to ensure: that each file contained the

points located within that tile; that tiles were completely filled; that the point density per tile was within expected ranges,

and that the tiles were correctly named.

Conceptual Consistency:

Computational Consulting Services, the LIDAR processing vendor used proprietary algorithms to remove

features and artifacts in the First and Last Return data that did not reflect true ground elevation. Subsequent quality assurance

testing by Dewberry determined that the data met FEMA and MD DNR specifications for both vertical accuracy and other consistencies

with accepted standards. The QA report can be accessed at


Process Steps

Process Step 1

CC ID: 1135339

LIDAR Data Acquisition. Airborne 1, Inc. flew the project area with the LIDAR sensor. In an effort to permit

correlation of the point values with tidal gauge stations, Airborne 1, Inc. was required to fly tidal shoreline areas during

the low tide cycle (slack water - low tide - slack water) as predicted by local tide stations. The LIDAR sensor collected raw

data that was referenced in UTM. The flight plan on this project included the following specifications to meet the project

requirements: *Single pass density - 1.544 square meters per sample; *Average area sampling density -1.52 square meters per sample;

*Swath width - 891.32 meters; *Flight altitude -1371 meters (4500 ft); *Flight line spacing - 445.66 meters w/50% overlap;

*Scan frequency - 22 Hz; *Firing rate - 25 kHz; *Scan angle - 18 degrees; *Ground speed - 130 knots. When complete, the raw data

was delivered to Spatial Systems.

Process Date/Time: 2005-04-24 00:00:00

Process Step 2

CC ID: 1135340

LIDAR Data Processing. Computational Consulting Systems. The First and Last Return data was delivered to CCS

in large blocks of data. CCS processed the data using both the First and Last Returns, removed artifacts using automated and manual

techniques, and reprojected the data into the client-specified X, Y, Z text files using the 1200 meter x 1800 meter tiles, NAD 83

meters, NAVD 88 meters. CCS also generated the Intensity Imagery using the client-specified USGS 3.75' tiling scheme. The data

products were delivered to SSA for quality assurance testing, formatting and final delivery.

Process Date/Time: 2005-08-30 00:00:00

Process Step 3

CC ID: 1135341

LIDAR Data Post Processing. Spatial Systems Associates. SSA digitized the shoreline from the Intensity Imagery

for the purposes of delineating a shoreline. Any LIDAR points that fell seaward of this shoreline were assigned the value of

zero (0). In addition to the shoreline, SSA delineated upland ponds using the same technique and assigned all LIDAR points that

fell within the water area the value of the lowest observed point close to the shore. The observed elevation values were not lost;

a fourth field in the data file was added for the assigned value. SSA also performed a variety of QA procedures to determine if

the point density was within expected ranges; that each tile was completely filled; that all tiles were accounted for, and that

the tiles were named in accordance with client specifications.

Process Date/Time: 2005-09-30 00:00:00

Process Step 4

CC ID: 1135342

LIDAR Data Check Point Surveys. NXL Construction Services. NXL was contracted to acquire the check-points in

the 5 different land cover classes. SSA provided NXL with maps of each area where a check-point was to be located. The points

were scattered throughout the project area. NXL was permitted the latitude to select the exact location based on field conditions,

provided the points were generally within a 1 mile radius of the chosen location and that the land cover class was the same as the

one specified. The land cover classes were: Grass/Ground, High Grass/Crops, Brush/Low Trees, Forest, and Urban/Pavement.

Process Date/Time: 2005-06-30 00:00:00

Process Step 5

CC ID: 1135343

LIDAR Data Quality Assurance. Dewberry LLC was provided with the check-point and LIDAR Bare Earth Mass Points

data to perform their independent quality assurance work. They performed detailed analyses to determine if the vertical accuracy

was within specifications and examined the data for flight, data collection and processing inconsistencies. Neither the flight

vendor (Airborne 1) nor the processing vendor (CCS) was given access to the check-point data. The entire accuracy report can be

found at

Process Date/Time: 2005-09-30 00:00:00

Process Step 6

CC ID: 1135344

The NOAA Office for Coastal Management (OCM) received LAS files containing the point cloud elevation data from

Earth Data, Inc. OCM performed the following processing on the data to make it available within the Lidar Data Retrieval Tool


1. Variable length header records were added to the LAS files to identify projection, datum and sort order.

2. The LFIT files were sorted by latitude.

3. Lfit files were exported to xyz ASCII text.

Process Date/Time: 2006-11-01 00:00:00

Catalog Details

Catalog Item ID: 49783
GUID: gov.noaa.nmfs.inport:49783
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-15 15:22+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2022-08-09 17:11+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