Slide Menu
Search Help Show/Hide Menu
Short Citation:
OCM Partners, 2022: 2006 URS Corporation Bare Earth Topographic Lidar: Shawsheen River, Massachusetts, https://www.fisheries.noaa.gov/inport/item/49771.

Item Identification

Title: 2006 URS Corporation Bare Earth Topographic Lidar: Shawsheen River, Massachusetts
Short Name: ma2006_urs_shawsheen_m2576_metadata
Status: Completed
Publication Date: 2013-10
Abstract:

URS Corporation contracted EarthData International to aquire topographic elevation data for 82 square miles in Essex

and Middlesex Counties, Massachusetts during 2006. Products generated include lidar point clouds, 3D hydro breaklines,

and lidar bare-earth elevation models in LAS format using lidar collected with a Leica ALS-50 Aerial Lidar Sensor.

Lidar Sensor Specifications:

Sensor: Leica ALS-50 Aerial Lidar Sensor (s/n ALS036)

Airspeed: ~ 130 knots

Laser Pulse Rate: 38,000 Hz

Field of View: 35 Degrees

Scan Rate: 20 Hz

Average Swath Width: 1537 meters

Nominal Post Spacing 3 meters

Purpose:

The purpose of these data is to provide elevation data capable of supporting generation of two foot contours and

defining target drainage channel geometry.

Notes:

10415

Supplemental Information:

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

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2576/supplemental/ma2006_urs_shawsheen_footprint.KMZ

Keywords

Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category
elevation
UNCONTROLLED
None LAZ

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 (ASPRS Class 2)

Entity Attribute Detail Citation:

none

Distribution Liability:

Any conclusions drawn from the analysis of this information are not the responsibility of URS Corporation, EarthData International, NOAA,

the Office for Coastal Management or its partners.

Data Set Credit: Please credit URS Corporation and EarthData International for all products derived from this data.

Support Roles

Data Steward

CC ID: 676359
Date Effective From: 2013-10
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Distributor

CC ID: 676361
Date Effective From: 2013-10
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Metadata Contact

CC ID: 676362
Date Effective From: 2013-10
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Point of Contact

CC ID: 676360
Date Effective From: 2013-10
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Extents

Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1134722
W° Bound: -71.308999
E° Bound: -71.122943
N° Bound: 42.725917
S° Bound: 42.443801

Extent Group 1 / Time Frame 1

CC ID: 1134721
Time Frame Type: Discrete
Start: 2006-12-16

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:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2576

;

Data Access Constraints:

None

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: 741252
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2576
Distributor:
File Name: Customized Download
Description:

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

Distribution 2

CC ID: 741253
Download URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2576/index.html
Distributor:
File Name: Bulk Download
Description:

Simple download of data files.

URLs

URL 1

CC ID: 741255
URL: https://coast.noaa.gov/dataviewer
URL Type:
Online Resource

URL 2

CC ID: 741256
URL: https://coast.noaa.gov
URL Type:
Online Resource

URL 3

CC ID: 741257
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2576/supplemental/ma2006_urs_shawsheen_footprint.KMZ
Name: Browse Graphic
URL Type:
Browse Graphic
File Resource Format: kmz
Description:

This graphic shows the lidar coverage for Essex and Middlesex Counties, Massachusetts.

Activity Log

Activity Log 1

CC ID: 676380
Activity Date/Time: 2016-05-23
Description:

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 676379
Activity Date/Time: 2017-11-14
Description:

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

Activity Log 3

CC ID: 718338
Activity Date/Time: 2018-02-08
Description:

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 741254
Activity Date/Time: 2018-03-13
Description:

Partial upload to move data access links to Distribution Info.

Data Quality

Accuracy:

1. The bare-earth points have a Fundamental Vertical Accuracy of 1.2 ft. (36.3 cm) or better at the 95% confidence level in open terrain,

after correction of systematic errors, computed by multiplying the RMSEz by 1.9600. This is equivalent to a vertical RMSE of 0.6 ft.

(18.5 cm) or less in open terrain, equivalent to 2 foot contours that satisfy National Map Accuracy Standards.

2. In all land cover categories combined, the bare-earth dataset has a Consolidated Vertical Accuracy of 1.6 ft. (49.0 cm) or better at the

95% confidence level, computed by the 95th percentile method of endorsement by the National Digital Elevation Program.

3. The horizontal accuracy meets or exceeds 5.68 ft. (1 meter) or less.

Horizontal Positional Accuracy:

The lidar data fully comply with FEMA guidance as published in Appendix A, April 2003.

Vertical Positional Accuracy:

Terrasurv performed a geodetic control survey in support of LIDAR mapping. The bare-earth points have a Fundamental Vertical Accuracy of

1.2 ft. (36.3 cm) or better at the 95% confidence level in open terrain, after correction of systematic errors, computed by multiplying

the RMSEz by 1.9600. This is equivalent to a vertical RMSE of 0.6 ft. (18.5 cm) or less in open terrain, equivalent to 2 foot contours that

satisfy National Map Accuracy Standards.

In all land cover categories combined, the bare-earth dataset has a Consolidated Vertical Accuracy of 1.6 ft. (49.0 cm) or better at the

95% confidence level, computed by the 95th percentile method of endorsement by the National Digital Elevation Program. The vertical accuracy

of the lidar data fully complies with FEMA guidance as published in Appendix A, April 2003 and National Standard for Spatial Accuracy (NSSDA).

; Quantitative Value: 0.185 meters, Test that produced the value: Tested Vertical Root Mean Square Error (RMSEz) in open area. Units in meters.

Completeness Report:

Two checks for completeness were performed:

1. EarthData's proprietary software, Checkedb, for verification agianst ground survey points.

2. Terrascan, for verification of automated and manual editing and final QC of products.

Conceptual Consistency:

Compliance with the accuracy standard was ensured by the placement of GPS ground control prior to the acquisition of lidar data. The following

checks were performed.

1. The ground control and airborne GPS data stream were validated through a fully analytical boresight adjustment.

2. The DTM (Digital Terrain Model) data were checked against the project control.

3. Lidar elevation data was validated through an inspection of edge matching and visual inspection for quality (artifact removal).

Lineage

Process Steps

Process Step 1

CC ID: 1134715
Description:

Terrasurv was tasked to perform a geodetic control survey in support of LIDAR mapping of the Shawsheen river area in Essex and Middlesex Counties,

Massachusetts. The Global Positioning System (GPS) was used in a static differential mode to measure the interstation vectors of the network. The

National Spatial Reference System (NSRS) was used to provide control for the network. Continuously Operating Reference Station WMTS was used, along

with two ground stations of the NSRS. Two Trimble dual frequency receivers were used on day 361 of 2006. A base receiver was set up near on C 35, at

the Lawrence Municipal Airport. This point was also used by the flight crew during the aerial data acquisition phase. The two northerly LIDAR points

(SR-1 and SR-5) were surveyed using this station as a base. The other three LIDAR stations, and benchmark V 34, were surveyed using the CORS as a

base. The horizontal datum was the North American Datum of 1983, 1996 adjustment (NAD 1983 1996), and the vertical datum was the North American

Vertical Datum of 1988 (NAVD 1988) Geoid03.

Process Date/Time: 2006-12-27 00:00:00

Process Step 2

CC ID: 1134716
Description:

URS contracted EarthData International, Inc. (EarthData) to collect and deliver high quality topographic elevation point data derived from multiple

return, light detection and ranging (Lidar) measurements for an area of interest totaling approximately 82 square miles in Essex and Middlesex

Counties, Massachusetts. Data was collected at a nominal three meter (3) meter post spacing between points at an altitude of 2438 meters (8,000 feet)

above mean terrain. This data was used to produce a bare-earth surface model and hydro-enforced breaklines for the project. The aerial acquisition

was conducted on 16 December, 2006 using and aircraft (tail number N2636P). Lidar data was captured using an ALS-50 Lidar system, s/n ALS036,

including an inertial measuring unit (IMU) and a dual frequency GPS receiver.

Process Date/Time: 2006-12-16 00:00:00

Process Step 3

CC ID: 1134717
Description:

EarthData has developed a unique method for processing lidar data to identify and remove elevation points falling on vegetation, buildings, and

other aboveground structures. The algorithms for filtering data were utilized within EarthData's proprietary software and commercial software written

by TerraSolid. This software suite of tools provides efficient processing for small to large-scale, projects and has been incorporated into ISO 9001

compliant production work flows. The following is a step-by-step breakdown of the process.

1. Using the lidar data set provided by EarthData, the technician performs calibrations on the data set.

2. Using the lidar data set provided by EarthData, the technician performed a visual inspection of the data to verify that the flight lines overlap

correctly. The technician also verified that there were no voids, and that the data covered the project limits. The technician then selected a

series of areas from the data set and inspected them where adjacent flight lines overlapped. These overlapping areas were merged and a process

which utilizes 3-D Analyst and EarthData's proprietary software was run to detect and color code the differences in elevation values and profiles.

The technician reviewed these plots and located the areas that contained systematic errors or distortions that were introduced by the lidar sensor.

3. Systematic distortions highlighted in step 2 were removed and the data was re-inspected. Corrections and adjustments can involve the application

of angular deflection or compensation for curvature of the ground surface that can be introduced by crossing from one type of land cover to

another.

4. The lidar data for each flight line was trimmed in batch for the removal of the overlap areas between flight lines. The data was checked against

a control network to ensure that vertical requirements were maintained. Conversion to the client-specified datum and projections were then

completed. The lidar flight line data sets were then segmented into adjoining tiles for batch processing and data management.

5. The initial batch-processing run removed 95% of points falling on vegetation. The algorithm also removed the points that fell on the edge of

hard features such as structures, elevated roadways and bridges.

6. The operator interactively processed the data using lidar editing tools. During this final phase the operator generated a TIN based on a desired

thematic layers to evaluate the automated classification performed in step 5. This allowed the operator to quickly re-classify points from one

layer to another and recreate the TIN surface to see the effects of edits. Geo-referenced images were toggled on or off to aid the operator in

identifying problem areas. The data was also examined with an automated profiling tool to aid the operator in the reclassification.

7. The point cloud data were delivered in LAS format.

Process Date/Time: 2007-02-28 00:00:00

Process Step 4

CC ID: 1134718
Description:

3-D breaklines were created for the creation of a completely new hydrology dataset specifically tailored to meets the needs of the users of terrain

data.

1) Breaklines were generated for all streams draining greater than approximately 1 square mile.

2) Two-dimensional lines defining the centerline and banks of those streams were manually digitized into Microstation format from the available 2002

source digital aerial imagery using lidar hillshades as an ancillary reference.

3) Breaklines were collected, unbroken through closed water bodies and culverts, as well as under roads, railroads, and bridges, in order to maintain

proper stream network connectivity.

4) The entire breakline dataset was checked to ensure integrity of the linework with respect to topologic structure, connectivity, and positive downhill

stream flow.

5) Single line streams were collected with the following criteria: Any area of drainage that did not meet the criteria to be collected as a double banked

stream or closed water body.

6) Double-banked streams were collected with the Any area of drainage that was at least 40 feet wide for a distance of greater than 540 feet, and

excluding closed water bodies. Double banked streams were delivered as linear features.

7) Artificial path lines were collected as the center line for all double banked streams and closed water bodies. Artificial paths were also created for

closed water bodies where no flow path was delineated coming into or leaving the water body, and/or where the closed water body existed as the origin

source of a flow path.

8) Artificial paths that are drawn in the two instances above go through the center of the water body and stop halfway through it. Artificial paths were

only drawn for water bodies that fell on a streamline.

9) Any islands found within water bodies were collected in instances where trees were visible on them (indicating that these are permanent features). These

islands were delivered as separate polyline features if present.

10) Any and all closed water bodies were collected, regardless of size, excluding such features as swimming pools, for the entire project area.

11) Water bodies were delivered as polygon features.

12) Single line streams, double banked streams, artificial paths and closed water bodies have unique attribution such that one feature type can be easily

distinguished from another.

13) Linework was delivered in ESRI shape file format.

14) The 3D Hydro Breaklines were developed for the sole purpose of supporting flood mapping and should not be used to generate contours

Process Date/Time: 2007-02-28 00:00:00

Process Step 5

CC ID: 1134719
Description:

The NOAA Office for Coastal Management (OCM) received topographic files las V1.1 format. The files contained lidar elevation measurements, Class 2 Points, return

information, scan angle, intensity values and GPS Week Time. The data were received in Massachusetts State Plane Mainland Zone 2001, NAD83 coordinates

and were vertically referenced to NAVD88 using the Geoid03 model. The vertical units of the data were meters. OCM performed the following processing for

data storage and Digital Coast provisioning purposes:

1. The GPS Week Time was converted to Adjusted Standard GPS Time.

2. The las files were changed from V 1.1 to V 1.2.

3. The las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid03.

4. The las files were converted from a Projected Coordinate System (MA SP Mainland) to a Geographic Coordinate System (NAD83).

5. The las files' horizontal units were converted from meters to decimal degrees.

Process Date/Time: 2013-10-01 00:00:00

Catalog Details

Catalog Item ID: 49771
GUID: gov.noaa.nmfs.inport:49771
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