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Short Citation:
OCM Partners, 2023: Connecticut Statewide Lidar DEM 2016, https://www.fisheries.noaa.gov/inport/item/49408.

Item Identification

Title: Connecticut Statewide Lidar DEM 2016
Short Name: 2016_CT_DEM_m8396_metadata
Status: Completed
Publication Date: 2017-10-20
Abstract:

This metadata record describes the hydro-flattened bare earth digital elevation model (DEM) derived from the classified LiDAR data for the 2016 Connecticut Lidar project covering approximately 5,240 square miles.

Original contact information:

Contact Org: NOAA Office for Coastal Management

Phone: 843-740-1202

Email: coastal.info@noaa.gov

Purpose:

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments, and hydrologic modeling. LAS data products are suitable for 1 foot contour generation. USGS Lidar Base Specification 1.2, QL2. 19.6 cm NVA.

Notes:

12073

Supplemental Information:

Project Projection, Datums and Units: Projection - State Plane Connecticut; Horizontal datum - North American Datum of 1983 (NAD83 (2011)); Vertical datum - North American Vertical Datum of 1988 (NAVD88) using the latest geoid (Geoid12b) for converting ellipsoidal heights to orthometric heights; Units - US feet horizontal, meters vertical. This data was ingested into the Digital Coast Data Access Viewer for custom processing. If you requested this data through that system, your projection may be different and will be reflected below.

Keywords

Theme Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > TOPOGRAPHICAL RELIEF MAPS
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > OCEANS > COASTAL PROCESSES > COASTAL ELEVATION
ISO 19115 Topic Category
elevation
ISO 19115 Topic Category
oceans
UNCONTROLLED
CT ALS70
CT Bare Earth
CT Contour
CT Digital Elevation Model (DEM)
CT Digital Terrain Model (DTM)
CT First Return
CT Grid
CT ground points
CT IMG
CT Intensity return
CT LAS
CT LiDAR
CT LMS-Q680i
CT mapping
CT Overlap points
CT point cloud
CT Unclassified points
CT Water points

Temporal Keywords

Thesaurus Keyword
UNCONTROLLED
None 2016

Spatial Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > CONNECTICUT
UNCONTROLLED
CT Connecticut
CT United States

Physical Location

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

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: Unknown
Data Presentation Form: point digital data (LAS)
Entity Attribute Overview:

Bare Earth only

Classes:

2 - Bare-Earth Ground

Entity Attribute Detail Citation:

USGS Base Specification 1.2, QL2 meeting 19.6 cm NVA

Distribution Liability:

The Capitol Region Council of Governments digital data have been tested and their documentation carefully reviewed. However, the Capitol Region Council of Governments and its representatives make no warranty or representation, either expressed or implied, with respect to the digital data and their documentation, their quality, performance, merchantability, or fitness for a particular purpose. The digital data are distributed on "as is" basis, and the user assumes all risk to their quality, the results obtained from their use, and the performance of the data. In no event will the Capitol Region Council of Governments or its representatives be liable for any direct, indirect, special, incidental or consequential damages resulting from and defect in the State of Connecticut or in their documentation. This disclaimer of warranty is exclusive and in lieu of all others, oral or written, express or implied. No agent or employee is authorized to make any modification, extension, or addition to this warranty.

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

Support Roles

Data Steward

CC ID: 660969
Date Effective From: 2017-10-20
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: 660971
Date Effective From: 2017-10-20
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: 660972
Date Effective From: 2017-10-20
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: 660970
Date Effective From: 2017-10-20
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: 1151447
W° Bound: -73.745809
E° Bound: -71.782632
N° Bound: 42.063615
S° Bound: 40.971166

Extent Group 1 / Time Frame 1

CC ID: 1151446
Time Frame Type: Range
Start: 2016-03-11
End: 2016-04-16

Spatial Information

Spatial Representation

Representations Used

Grid: Yes

Access Information

Security Class: Unclassified
Data Access Constraints:

This data may be used by the requesting party at their own risk and may be re-distributed.

Data Use Constraints:

This data is for planning purposes only and should not be used for legal or cadastral purposes. Any conclusions drawn from analysis of this information are the responsibility of the user. Users should be aware that temporal changes may have occurred since this dataset was collected and some parts of this dataset may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations.

Distribution Information

Distribution 1

CC ID: 720720
Start Date: 2017
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=8396
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2017-10-20 - Present)
File Name: Customized Download
Description:

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

File Type: Zip

Distribution 2

CC ID: 720721
Start Date: 2017
End Date: Present
Download URL: https://coast.noaa.gov/htdata/raster2/elevation/CT_statewide_DEM_2016_8396
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2017-10-20 - Present)
File Name: Bulk Download
Description:

Simple download of data files.

URLs

URL 1

CC ID: 720723
URL: https://coast.noaa.gov/dataviewer
URL Type:
Online Resource

URL 2

CC ID: 720724
URL: https://coast.noaa.gov
URL Type:
Online Resource

URL 3

CC ID: 720725
URL: http://crcog.org
URL Type:
Online Resource

URL 4

CC ID: 1042840
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/8392/supplemental/Final_LiDAR_Report_CRCOG_2016.pdf
Name: Lidar Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to the Lidar Report.

Activity Log

Activity Log 1

CC ID: 661003
Activity Date/Time: 2017-10-05
Description:

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 661002
Activity Date/Time: 2017-11-14
Description:

Converted from FGDC CSDGM (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

Activity Log 3

CC ID: 718088
Activity Date/Time: 2018-02-08
Description:

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 720722
Activity Date/Time: 2018-02-13
Description:

Partial upload to move data access links to Distribution Info.

Data Quality

Accuracy:

State of Connecticut:

The LiDAR surface was evaluated using a collection of 181 GPS surveyed checkpoints for the raw NVA report. The DEM was compared to these checkpoints yielding a better result than was required for the project.

Raw NVA Control Accuracy Report (feet)

--------- Report Disclaimer ---------

This report does not guarantee accuracy. The report only reflects one statistical representation of the control points, LIDAR data and surface used. This report does not replace a thorough quality control process.

--------- Report Summary ---------

Average dz 0.004

Minimum dz -0.829

Maximum dz 0.622

Average magnitude 0.170

Root mean square 0.227

Std deviation 0.228

----------------------------------------------------------------------------------------

Attribute accuracy is tested after the LiDAR processing stage. After classification of the LiDAR data, DEMs are created using the bare earth points. The NVA report is generated from the comparison of the DEM and the ground control collected within the project area.

The DEM surface was evaluated using a collection of 181 GPS surveyed checkpoints for the NVA report. The DEM was compared to these checkpoints yielding much better result than was required for the project.

NVA Control Accuracy Report (feet)

--------- Report Disclaimer ---------

This report does not guarantee accuracy. The report only reflects one statistical representation of the control points, LIDAR data and surface used. This report does not replace a thorough quality control process.

--------- Report Summary ---------

Average dz 0.004

Minimum dz -0.778

Maximum dz 0.576

Average magnitude 0.158

Root mean square 0.207

Std deviation 0.207

----------------------------------------------------------------------------------------

Attribute accuracy is tested after the LiDAR processing stage. After classification of the LiDAR data, DEMs are created using the bare earth points. The VVA report is generated from the comparison of the DEM and the ground control collected within the project area.

The DEM was evaluated using a collection of 95 GPS surveyed checkpoints. The DEM was compared to these checkpoints yielding much better result than was required for the project.

VVA Control Accuracy Report (feet)

--------- Report Disclaimer ---------

This report does not guarantee accuracy. The report only reflects one statistical representation of the control points, LIDAR data and surface used. This report does not replace a thorough quality control process.

--------- Report Summary ---------

Average dz 0.147

Minimum dz -0.771

Maximum dz 0.625

Average magnitude 0.212

Root mean square 0.261

Std deviation 0.217

---------------------------------------------------------------------------------------- | Quantitative Value: 0 | Quantitative Test Explanation: N/A

Horizontal Positional Accuracy:

Horizontal positional accuracy for the Connecticut LiDAR is dependent upon the quality of the GPS/INS solution, sensor calibration and ground conditions at the time of data capture. The data set was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 1.0 meter RMSEx/RMSEy.; Quantitative Value: 1.0 meters, Test that produced the value: For the Connecticut, this value is computed by comparing ground control to a DEM derived from the classified LiDAR data and represents the RMSE of residuals on controls within the project area.

Vertical Positional Accuracy:

For the DEM data derived from the classified point cloud, the NVA and VVA were computed. The vertical accuracy was tested with independent survey check points located in various terrain types within Connecticut. These check points were not used in the calibration or post processing of the lidar point cloud data. The survey check points were distributed throughout the block area. Specifications for this project require that the VVA be 19.6 cm or better @ 95 percent confidence level.; Quantitative Value: 0.070 meters, Test that produced the value: Value is RMSE in meters. The raw NVA was tested using 181 independent survey check points located in flat terrain types within the state of Connecticut The survey checkpoints were distributed throughout the block area. The 181 independent check points were surveyed using static GPS base stations collecting point location for 20 minute intervals. Elevations were measured for the x,y,z location of each check point. Elevations interpolated from the DEM surface were then compared to the elevation values of the surveyed control. This data set was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10cm RMSEz Vertical Accuracy Class. Actual NVA accuracy was found to be RMSEz = 7cm, equating to +/- 13.8cm at 95% confidence level.; Quantitative Value: 0.063 meters, Test that produced the value: Value is RMSE in meters. The NVA was tested using 181 independent survey check points located in bare earth terrain types within the state of Connecticut. The 181 independent check points contained all NVA points and were surveyed using static GPS base stations collecting point location for 20 minute intervals. Elevations were measured for the x,y,z location of each check point. Elevations interpolated from the DEM surface were then compared to the elevation values of the surveyed control. This data set was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10cm RMSEz Vertical Accuracy Class. Actual NVA accuracy was found to be RMSEz = 6.3cm, equating to +/- 12.5cm at 95% confidence level.; Quantitative Value: 0.080 meters, Test that produced the value: Value is RMSE in meters. The VVA was tested using 95 independent survey check points located in various vegetation terrain types within the state of Connecticut. The 95 independent check points were surveyed using static GPS base stations collecting point location for 20 minute intervals. Elevations were measured for the x,y,z location of each check point. Elevations interpolated from the DEM surface were then compared to the elevation values of the surveyed control. This data set was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10cm RMSEz Vertical Accuracy Class. Actual NVA accuracy was found to be RMSEz = 6.3cm, equating to +/- 12.5cm at 95% confidence level. Actual VVA accuracy was found to be +/- 17cm at the 95th percentile.

Completeness Report:

LiDAR data is collected for the project area. Post processing of the simultaneously acquired GPS/INS is performed and applied to the laser returns to output a point cloud in the specified project coordinate system and datums. The point cloud data is then subjected to automated classification routines to assign all points in the point cloud to ground, water, overlap and unclassified point classes. Anomalous laser returns that occur infrequently are removed entirely from the data set. Once clean bare earth points are established, DEMs are created using bare earth points and hydro features. The DEM surface is then compared to the survey checkpoints. These accuracies must pass the NVA and VVA accuracy specifications.

Conceptual Consistency:

LiDAR data is collected within the project area and processed. After the DEMs were created, the dataset was verified against control. Well-distributed control was collected for the entire state of Connecticut. Accuracy is reported for the state as a whole.

Lineage

Sources

Classified lidar

CC ID: 1151431
Extent Type: Discrete
Extent Start Date/Time: 2016
Scale Denominator: 1200
Source Contribution:

The classified lidar point cloud is used to derive various data products such as, but not limited to, bare earth gridded DEM, triangulated irregular networks (TIN), contours, digital surface models (DSM). The output format is fully compliant LAS v1.4, Point Record Format 6 | Source Geospatial Form: Point digital data | Type of Source Media: disk

Ground control

CC ID: 1151432
Publish Date: 2010-01-01
Extent Type: Discrete
Extent Start Date/Time: 2016
Source Contribution:

Targeted ground control is used to create a digital control file and control report as well as QC check of LiDAR accuracy. Predefined points (NGS when available) within the project area are targeted. | Source Geospatial Form: tabular digital data | Type of Source Media: disc

LiDAR Data

CC ID: 1151433
Extent Type: Discrete
Extent Start Date/Time: 2016
Source Contribution:

Aerial LiDAR and GPS/IMU data are recorded for the defined project area at an altitude, flight speed, scanner swath width and scanner pulse frequency to achieve the design goals of the project. | Source Geospatial Form: Remote sensing image | Type of Source Media: disc

Post processed GPS/INS

CC ID: 1151434
Extent Type: Discrete
Extent Start Date/Time: 2016
Scale Denominator: 1200
Source Contribution:

Post processed GPS/INS is applied to the lidar point data to georeference each point in the project coordinate system | Source Geospatial Form: Tabular digital data | Type of Source Media: disk

Post processed lidar

CC ID: 1151435
Extent Type: Discrete
Extent Start Date/Time: 2016
Scale Denominator: 1200
Source Contribution:

The post processed lidar data has been projected and oriented in the specified coordinate system as an un-classified point cloud. | Source Geospatial Form: Point digital data | Type of Source Media: Disk

Tile Definition

CC ID: 1151436
Extent Type: Discrete
Extent Start Date/Time: 2016
Scale Denominator: 1200
Source Contribution:

The tile definition defines discreet non-overlapping rectangular areas used as cut lines to break up the large classified lidar dataset into smaller, more manageable data tiles. Each tile is 2500ft by 2500ft in dimension. | Source Geospatial Form: raster digital data | Type of Source Media: disk

Process Steps

Process Step 1

CC ID: 1151437
Description:

At selected locations throughout the site, accurate GPS coordinates and elevations are surveyed and the points are marked with targets. | Source Produced: Ground control

Process Date/Time: 2016-01-01 00:00:00

Process Step 2

CC ID: 1151438
Description:

New LiDAR data is captured for the project area using a Leica ALS70 LiDAR instrument an integrated IPAS20 GPS/INS system mounted within a Aero Commander twin engine airplane.

Process Date/Time: 2016-01-01 00:00:00

Process Step 3

CC ID: 1151439
Description:

The airborne GPS data is post-processed in Inertial Explorer software and LEICA CloudPro software to determine the LiDAR sensor's angle and orientation in the terrain (project) coordinate system and datums during the survey.

Process Date/Time: 2016-01-01 00:00:00

Process Step 4

CC ID: 1151440
Description:

The post processed GPS/INS solution is applied to the raw lidar data to orient and project the data points into the project area reference system as an unclassified point cloud. | Source Produced: Classified lidar

Process Date/Time: 2016-01-01 00:00:00

Process Step 5

CC ID: 1151441
Description:

The georeferenced lidar data is then classified and edited in Terrasolid Terrascan software. Data is classified to produce: Class 1: unclassified, Class 2: ground, Class 7: low point, Class 9: water, Class 10: ignored ground, Class 17: bridge deck, Class 18: high noise. | Source Produced: Classified lidar

Process Date/Time: 2016-01-01 00:00:00

Process Step 6

CC ID: 1151442
Description:

The classified lidar data is exported as 2500 X 2500 foot tiles in the LAS format with any or all classes required to produce derivative products. | Source Produced: Classified lidar

Process Date/Time: 2016-01-01 00:00:00

Process Step 7

CC ID: 1151443
Description:

The NOAA Office for Coastal Management (OCM) received the digital elevation model (DEM) files in a proprietary ESRI format. The files were extracted using GDAL to create GeoTiff files. It was found that ArcGIS could not properly read GeoTiff files with EPSG georeferencing for NAD83(2011) Connecticut State Plane. The files were translated to Imagine files using gdal_translate -a_srs EPSG:6434+5703 and at the same time converted to vertical meters. The vertical meters were a requirement for DEM ingestion into the Digital Coast Data Access Viewer. The data use the Geoid12b model.

Process Date/Time: 2017-10-01 00:00:00
Process Contact: NOAA Office for Coastal Management (NOAA/OCM)
Phone (Voice): (843) 740-1202
Email Address: coastal.info@noaa.gov

Process Step 8

CC ID: 1151444
Description:

The DEMs were converted to vertical feet after the Data Access Viewer was modified to handle feet. The vertical meter imagine format data were moved to a subdirectory vert_meters. The files were converted to Tiffs using gdal_translate and spatial referencing specified with -a_srs EPSG:6434+6360. There is a known ArcGIS bug reading that georeferencing correctly.

Process Date/Time: 2021-02-17 00:00:00
Process Contact: NOAA Office for Coastal Management (NOAA/OCM)
Phone (Voice): (843) 740-1202
Email Address: coastal.info@noaa.gov

Related Items

Item Type Relationship Type Title
Data Set (DS) Cross Reference Connecticut Statewide LiDAR 2016 - Blocks 1-7

Catalog Details

Catalog Item ID: 49408
GUID: gov.noaa.nmfs.inport:49408
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-15 15:12+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