Slide Menu
Search Help Show/Hide Menu
Short Citation:
OCM Partners, 2023: 2018 Town of Nantucket Lidar DEM: Nantucket Island, MA, https://www.fisheries.noaa.gov/inport/item/67488.

Item Identification

Title: 2018 Town of Nantucket Lidar DEM: Nantucket Island, MA
Status: Completed
Creation Date: 2018
Publication Date: 2018-10-15
Abstract:

Product: Bare earth Digital Elevation Model (DEM) data.

Geographic Extent: Nantucket county Massachusetts, covering approximately 91 square miles.

Dataset Description: The Nantucket project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.7 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011), State Plane, Feet and vertical datum of NAVD88 (GEOID12B), Feet. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 1,577 individual 1250 ft x 1250 ft tiles, as tiled Intensity Rasters, and as tiled bare-earth DEM; all tiled to the same 1250 ft x 1250 ft schema.

Ground Conditions: Lidar was collected in early to mid 2018, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Sanborn Map Company, Inc. established a total of 20 ground control points that were used to calibrate and validate the lidar to known ground locations established throughout the project area.

In addition to these lidar point data, the bare earth Digital Elevation Models (DEM) created from the lidar point data are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

Purpose:

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare-earth surface. This allows the user to create Intensity Images, Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 2 foot cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

Supplemental Information:

Raster File Type = TIF Bit Depth/Pixel Type = 32-bit float Raster Cell Size = 2 Foot Interpolation or Resampling Technique = Triangulated Irregular Network Required Vertical Accuracy = 0.643 ft NVA

Keywords

Theme Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > DIGITAL ELEVATION/TERRAIN MODEL (DEM)
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > OCEANS > COASTAL PROCESSES > COASTAL ELEVATION
ISO 19115 Topic Category
elevation

Spatial Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > MASSACHUSETTS
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > LAND SURFACE

Instrument Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Instrument Keywords
LIDAR > Light Detection and Ranging

Platform Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Platform Keywords
AIRCRAFT

Physical Location

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

Data Set Information

Data Set Scope Code: Data Set
Data Set Type: Elevation
Maintenance Frequency: None Planned
Data Presentation Form: Model (digital)
Distribution Liability:

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

Data Set Credit: Sanborn Map Company, Inc., Town of Nantucket

Support Roles

Data Steward

CC ID: 1177178
Date Effective From: 2022
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: 1177177
Date Effective From: 2022
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: 1177179
Date Effective From: 2022
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: 1177180
Date Effective From: 2022
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: 1177197
W° Bound: -70.3240401506
E° Bound: -69.9511498712
N° Bound: 41.3971284252
S° Bound: 41.2321234447

Extent Group 1 / Time Frame 1

CC ID: 1177196
Time Frame Type: Range
Start: 2018-05-01
End: 2018-10-15

Spatial Information

Reference Systems

Reference System 1

CC ID: 1177199

Coordinate Reference System

CRS Type: Vertical
EPSG Code: EPSG:6360
EPSG Name: NAVD88 height (ftUS)
See Full Coordinate Reference System Information

Reference System 2

CC ID: 1177205

Coordinate Reference System

CRS Type: Projected
EPSG Code: EPSG:6490
EPSG Name: NAD83(2011) / Massachusetts Island (ftUS)
See Full Coordinate Reference System Information

Access Information

Security Class: Unclassified
Data Access Procedure:

Data is available online for bulk and custom downloads.

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.

Distribution Information

Distribution 1

CC ID: 1177182
Start Date: 2022-06-29
End Date: Present
Download URL: https://chs.coast.noaa.gov/htdata/raster5/elevation/MA_Nantucket_DEM_2018_9552
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2022 - Present)
File Name: Bulk Download
Description:

Bulk download of data files in GeoTiff format, MA Island State Plane NAD83(2011) US survey feet coordinates and orthometric heights in feet.

File Type: GeoTIFF

Distribution 2

CC ID: 1177181
Start Date: 2022-06-29
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9552/details/9552
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2022 - Present)
File Name: Customized Download
Description:

Create custom data files by choosing data area, product type, map projection, file format, datum, etc. A new metadata will be produced to reflect your request using this record as a base. Change to an orthometric vertical datum is one of the many options.

File Type: Zip
Compression: Zip

URLs

URL 1

CC ID: 1177183
URL: https://coast.noaa.gov/dataviewer/
Name: NOAA's Office for Coastal Management (OCM) Data Access Viewer (DAV)
URL Type:
Online Resource
File Resource Format: HTML
Description:

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

URL 2

CC ID: 1177184
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9551/supplemental/ma2018_nantucket_m9551.kmz
Name: Browse Graphic
URL Type:
Browse Graphic
File Resource Format: KML
Description:

This graphic displays the footprint for this lidar data set.

URL 3

CC ID: 1177185
URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9551/details/9551
Name: Custom Point Download
URL Type:
Online Resource
File Resource Format: Zip
Description:

Link to custom download, from the Data Access Viewer (DAV), the lidar point data from which these raster Digital Elevation Model (DEM) data were created.

URL 4

CC ID: 1177206
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9551/supplemental/312018207_Nantucket_MA_Ortho_Lidar_Report_508OCM.pdf
Name: Lidar Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to the lidar report.

Data Quality

Vertical Positional Accuracy:

The project specifications require the accuracy (ACCz) of the derived DEM be calculated and reported in two ways: 1. The required Vertical Accuracy is: 0.643 ft at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 0.328 ft in the "bare earth" and "urban" land cover classes. This is a required accuracy. The Vertical Accuracy was tested with 20 control points located in bare earth and urban (non-vegetated) areas. The control points were distributed throughout the project area and were surveyed using GPS techniques. AccuracyZ has been tested to meet 0.643 ft or better Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.

Tested 0.215 feet at a 95% confidence level (or 3.3 cm RMSE) using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The Vertical Accuracy of the DEM was calculated using 20 control points located in the Bare Earth and Urban land cover categories.

Completeness Report:

Datasets contain complete coverage of tiles. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. There are no void areas or missing data. The raw point cloud is of good quality and data passes Vertical Accuracy specifications.

Conceptual Consistency:

Data covers the entire area specified for this project.

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
Actual or Planned Long-Term Data Archive Location: NCEI-CO
How Will the Data Be Protected from Accidental or Malicious Modification or Deletion Prior to Receipt by the Archive?:

Data is backed up to tape and to cloud storage.

Lineage

Lineage Statement:

This data was provided by Mass GIS to the NOAA OCM for custom distribution by the NOAA Digital Coast Data Access Viewer (DAV) and bulk distribution via https.

Sources

Digital Elevation Models (DEMs)

CC ID: 1177191
Contact Role Type: Originator
Contact Type: Organization
Contact Name: Mass GIS
Citation URL: https://www.mass.gov/orgs/massgis-bureau-of-geographic-information
Citation URL Name: Mass GIS

Process Steps

Process Step 1

CC ID: 1177192
Description:

The following steps describe the Raw Data Processing and Calibration process: 1) Technicians processed the raw data to LAS format flight lines using the ABGNSS/IMU solution. 2) Technicians use TerraSolid TerraMatch to calculate initial calibration adjustment angles by mission and/or block. This is accomplished by identifying ground and above ground feature observations between flight-lines and calculating the offsets. The technician then analyzed the results and made any necessary additional adjustment until it is acceptable. 3) Once the angle calculation was completed the adjusted settings were applied to all of the flight-lines of the mission and/or block and checked for consistency. The technicians utilized commercial and proprietary software packages to analyze how well flight-line overlaps match and adjusted as necessary until the results met the project specifications. 4) The technicians checked and corrected the vertical misalignment of all flight-lines and also the matching between data and ground truth. The relative accuracy was less than or equal to 6 cm RMSEz within individual swaths and less than or equal to 8 cm RMSDz or within swath overlap (between adjacent swaths). 5) The technicians ran a final vertical accuracy check of the calibrated point cloud against the surveyed check points after the z correction to ensure the requirement of NVA = 19.6 cm 95% Confidence Level (Required Accuracy) was met. Point classification was performed according to USGS Lidar Base Specification 1.2, and breaklines were collected for water features. Bare earth DEMs were exported from the classified point cloud using collected breaklines for hydroflattening.

Process Date/Time: 2018-01-01 00:00:00

Process Step 2

CC ID: 1177193
Description:

LAS Point Classification: The point classification is performed as described below. The bare-earth surface is manually reviewed to ensure correct classification on the Class 2 (Ground) points. After the bare-earth surface is edited and QC'd, it is then used to generate all hydro-breaklines through heads-up digitization. All ground (ASPRS Class 2) lidar data inside of the Lake Pond and River Pond hydro flattening breaklines were then classified to water (ASPRS Class 9) using LP360 functionality. A buffer of 0.5 meters was also used around each hydro-flattened feature to classify these ground (ASPRS Class 2) points to Ignored ground (ASPRS Class 10). All Lake Pond Island and River Stream Island features were checked to ensure that the ground (ASPRS Class 2) points were reclassified to the correct classification after the automated classification was completed. All overlap data was processed through automated functionality provided by TerraScan to classify the overlapping flight-line data to approved classes by USGS. The overlap data was classified using standard LAS overlap bit. These classes were created through automated processes only and were not verified for classification accuracy. All data was manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler. Global Mapper is used as a final check of the bare-earth dataset. GeoCue was then used to create the deliverable industry-standard LAS files for the Classified Point Cloud Data. LAStools, LP360 and TerraScan software was used to perform statistical analysis of the classes in the LAS files, on a per tile level to verify classification metrics and full LAS header information.

Process Date/Time: 2018-10-12 00:00:00

Process Step 3

CC ID: 1177200
Description:

Hydro Flattened Raster DEM Process: Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 2 foot hydro-flattened Raster DEM. Using automated scripting routines within ArcMap, an GeoTIFF TIF file was created for each tile. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface.

Process Step 4

CC ID: 1177194
Description:

The NOAA Office for Coastal Management (OCM) was provided this data set from the office of Mass GIS. The total number of files received and processed was 1619. The data were in Massachusetts Island State Plane NAD83(2011), US survey feet coordinates and NAVD88 (Geoid12B) elevations in feet. The bare earth raster files were at a 2 feet grid spacing.

OCM performed the following processing on the data for Digital Coast storage and provisioning purposes:

1. Used internal an script to assign the EPSG codes (Horizontal EPSG: 6490 and Vertical EPSG: 6360) to the GeoTiff formatted files.

2. Copied the files to https.

Process Date/Time: 2022-06-30 00:00:00
Process Contact: Office for Coastal Management (OCM)

Related Items

Item Type Relationship Type Title
Data Set (DS) Cross Reference 2018 Town of Nantucket Lidar: Nantucket Island, MA

Catalog Details

Catalog Item ID: 67488
GUID: gov.noaa.nmfs.inport:67488
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2022-06-30 18:30+0000
Metadata Record Last Modified By: Rebecca Mataosky
Metadata Record Last Modified: 2022-10-05 13:48+0000
Metadata Record Published: 2022-06-30
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-06-30
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-06-30