49410
2015 City of Portland, Maine, Lidar
City_of_Portland_2015_DEM_m6270_metadata
Data Set
Published / External
49404
DEMs - partner (no harvest)
Project
Completed
2017-04-13
2015 City of Portland Maine Lidar Data Acquisition and Processing
Woolpert Order No. 75564
Contractor: Woolpert, Inc.
This task is for a high resolution data set of lidar covering approximately 21 square miles of the City of Portland, Maine.
The lidar data was acquired and processed under the requirements identified in this task order. Lidar data is a remotely sensed high resolution elevation data collected by an airborne platform. The lidar sensor uses a combination of laser range finding, GPS positioning, and inertial measurement technologies. The lidar systems collect data point clouds that are used to produce highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures, and vegetation. The task required the LiDAR data to be collected at a nominal pulse spacing (NPS) of 0.5 meters. The final products include classified LAS, four (4) feet pixel raster DEMs of the bare-earth surface in ERDAS IMG Format, and 8-bit intensity images. Each LAS file contains lidar point information, which has been calibrated, controlled, and classified. Additional deliverables include hydrologic breakline data, control data, tile index and FGDC project level metadata in .xml format. Ground conditions: Water at normal levels; no unusual inundation; no snow; leaf off. This metadata record is for the DEM data served by the NOAA Digital Coast.
The purpose of this project is to provide lidar and lidar derived products for the task order 2015 City of Portland Maine Lidar.
12079
Theme
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > TOPOGRAPHICAL RELIEF MAPS
Theme
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > OCEANS > COASTAL PROCESSES > COASTAL ELEVATION
Theme
ISO 19115 Topic Category
elevation
Spatial
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > MAINE
Theme
Project Level
Office for Coastal Management
Charleston
SC
Data Set
As Needed
Lidar
Any conclusions drawn from the analysis of this information are not the responsibility of the NOAA Office for Coastal Management, City of Portland, Woolpert, or their partners. Woolpert prepared the original data as set forth in the Scope of Services, in accordance with reasonable care and due diligence as set forth in this Agreement, however, due to the easily alterable nature of electronic media, files, documents, and other deliverables, Woolpert, Inc. makes no warranties, either expressed or implied, with respect to the accuracy, completeness, merchantability, or fitness for any particular purpose, including, but not limited to, use of any/all data as described within this metadata file, by any user of this data. Any use will be at the end-user's sole risk.
Woolpert flew and processed the original lidar data
Data Steward
2017-04-13
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Distributor
2017-04-13
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Metadata Contact
2017-04-13
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Point of Contact
2017-04-13
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Ground Condition
-70.347905
-70.237341
43.727922
43.635127
Discrete
2015-05-10
Yes
Vertical
EPSG:6360
NAVD88 height (ftUS)
North American Vertical Datum 1988
1
Gravity-related height
H
US survey foot
up
Projected
EPSG:26856
NAD83(HARN) / Maine West (ftUS)
NAD83 (High Accuracy Reference Network)
GRS 1980
20925604.4741667
298.257222101
NAD83(HARN)
SPCS83 Maine West zone (US Survey feet)
Transverse Mercator
Latitude of natural origin
42° 50' 0" N
Longitude of natural origin
70° 10' 0" W
Scale factor at natural origin
0.999966667
False easting
2952750
US survey foot
False northing
0
US survey foot
1
Easting
X
US survey foot
east
2
Northing
Y
US survey foot
north
Unclassified
This point cloud lidar data can be obtained on-line at the following URL:
https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6256.
This data can be obtained on-line at the following URL:
https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6270.
;
No restrictions apply to this data.
None. However, users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations.
2023-08-15
https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6270
2017-04-13
Organization
NOAA Office for Coastal Management
Customized Download
Create custom data files by choosing data area, product type, map projection, file format, datum, etc.
Zip
Zip
2023-08-15
https://noaa-nos-coastal-lidar-pds.s3.us-east-1.amazonaws.com/dem/MEGIS_Portland_ME_DEM_2015_6270/index.html
2017-04-13
Organization
NOAA Office for Coastal Management
Bulk Download
Simple download of data files.
GeoTIFF
GeoTIFF
https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/6256/supplemental/2015_portland_lidar_extent.kmz
Browse Graphic
Browse Graphic
kmz
This graphic shows the lidar footprint for the 2015 City of Portland, Maine, lidar project
https://coast.noaa.gov
Online Resource
https://coast.noaa.gov/dataviewer
Online Resource
2017-04-07
Date that the source FGDC record was last modified.
2017-11-14
Converted from FGDC Content Standard for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.
2018-02-08
Partial upload of Positional Accuracy fields only.
2018-02-13
Partial upload to move data access links to Distribution Info.
Compiled to meet 1.091 ft horizontal accuracy at 95 percent confidence level.; Quantitative Value: 0.333 meters, Test that produced the value: Lidar system specifications
Non-vegetated Vertical Accuracy (NVA) compiled to meet 0.297 ft NVA at a 95 percent confidence level, derived according to NSSDA, using 0.152 ft (RMSEz) x 1.96000 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines against the TIN and ground points.; Quantitative Value: 0.09 meters, Test that produced the value: Compiled to meet NVA at a 95 percent confidence level in meters.
The lidar data is visually inspected for completeness to ensure that are no void areas or missing data.
All formatted data cover the entire area specified for this project and are validated using a combination of commercial lidar processing software, GIS software, and proprietary programs to ensure proper formatting and loading prior to delivery.
Hydrologic breakline deliverable processing
2015-10-13
Discrete
2015-05-11
This data set is the project specified hydrologic breakline deliverable. | Type of Source Media: 3-d breakline dataset
Lidar acquisition
2015-10-13
Discrete
2015-05-10
This data set is the project specified acquired point cloud data. | Type of Source Media: Lidar dataset
Lidar deliverable processing
2015-10-13
Discrete
2015-05-11
This data set is the project specified lidar deliverables. | Type of Source Media: Lidar dataset
Survey Control Acquisition
2015-10-13
Discrete
2015
This data set is the project specified acquired ground control and QAQC control data. | Type of Source Media: Control dataset
Tile index and data extent
2015-10-13
Discrete
2015-05-11
This data set is the project specified tile index and data extent. | Type of Source Media: vector dataset
1
Using two Leica ALS70 (lidar) systems on board a Cessna 310 aircraft, high density data, at a nominal pulse spacing (NPS) of 0.5 meters, were collected for this task order (approximately 21 square miles). Leica Specs- AGL = 1,829 meters - Aircraft Speed = 140 Knots, Field of View (Full) = 28 degrees, Pulse Rate = 293 kHz, Scan Rate = 52.5 Hz, with an average side lap of 27.7%. Multiple returns were recorded for each laser pulse along with an intensity value for each return. One (1) mission was flown on May 10, 2015. One (1) Global Navigation Satellite System (GNSS) Base Station was used in support of the lidar data acquisition. Specific information regarding latitude, longitude, and ellipsoid height to the L1 phase center is included in the lidar processing report. Data for the task order is referenced to the NAD1983 (HARN) StatePlane Maine West FIPS 1802 in U.S. Survey Feet. The Vertical Datum is in NGVD29 with units in U.S. Survey Feet. Once the data acquisition and GPS processing phases are complete, the lidar data was processed immediately to verify the coverage had no voids. The GPS and IMU data was post processed using differential and Kalman filter algorithms to derive a best estimate of trajectory. The quality of the solution was verified to be consistent with the accuracy requirements of the project. The SBET was used to reduce the lidar slant range measurements to a raw reflective surface for each flight line. The coverage was classified to extract a bare earth digital elevation model (DEM) and separate last returns. The ALS70 calibration and system performance is verified on a periodic basis using Woolpert's calibration range. The calibration range consists of a large building and runway. The edges of the building and control points along the runway have been located using conventional survey methods. Inertial measurement unit (IMU) misalignment angles and horizontal accuracy are calculated by comparing the position of the building edges between opposing flight lines. The scanner scale factor and vertical accuracy is calculated through comparison of lidar data against control points along the runway. Field calibration is performed on all flight lines to refine the IMU misalignment angles. IMU misalignment angles are calculated from the relative displacement of features within the overlap region of adjacent (and opposing) flight lines. The raw lidar data is reduced using the refined misalignment angles.
2015-05-10T00:00:00
Lidar acquisition
2
Control used in calibration/accuracy reporting was provided by the City of Portland and delivered as ESRI shapefile
2015-01-01T00:00:00
Survey Control Acquisition
3
The individual flight lines were inspected to ensure the systematic and residual errors have been identified and removed. Then, the flight lines were compared to adjacent flight lines for any mismatches to obtain a homogeneous coverage throughout the project area. The point cloud underwent a classification process to determine bare-earth points and non-ground points utilizing "first and only" as well as "last of many" lidar returns. This process determined Default (Class 1), Ground (Class 2), Noise (Class 7), Water (Class 9), Ignored Ground (Class 10), Overlap Default (Class 17) and Overlap Ground (Class 18). The bare-earth (Class 2 - Ground) lidar points underwent a manual QA/QC step to verify the quality of the DEM as well as a peer-based QC review. This included a review of the DEM surface to remove artifacts and ensure topographic quality. Classification of water (class 9) and ignored ground (class 10) was completed via the use of the hydrologic breaklines collected for the hydro-flattening phase. The overlap classes were determined by first identifying the overlapping areas and reclassifying the LAS data by offset from a corridor. This allows the returns located on the edge of the swath to be removed from the bare earth coverage in an effort to produce a more uniform data density. The returns determined to be overlap including overlap default, ground, water, and ignored ground are then applied an overlap flag and reclassified to their respective standard classification value. The surveyed ground control points are used to make vertical adjustments to the data set and to perform the accuracy checks and statistical analysis of the lidar dataset. Supervisory QC monitoring of work in progress and completed editing ensured consistency of classification character and adherence to project requirements across the entire project area. The resulting deliverables for this task order consist of classified LAS file in LAS 1.4 format, 4 feet pixel size DEM files in ERDAS IMG format, 4 feet pixel size 8-bit Intensity files in GeoTIFF format, and Hydrologic Breakline data in ESRI shape file format.
2015-05-11T00:00:00
Lidar deliverable processing
4
The compilation procedure included use of lidar intensity, bare earth surface model, point cloud data, and open source imagery in an effort to manually compile hydrologic features in a 2-d environment. Following the compilation phase, a separate process was used to adjust the breakline data to best match the water level at the time of the lidar collection. Any ponds and/or lakes were adjusted to be at or just below the bank and to be at a constant elevation. Any streams were adjusted to be at or just below the bank and to be monotonic. Manual QAQC and peer-based QC review was performed on all delineated data to ensure horizontal placement quality and on all adjusted data to ensure vertical placement quality. The final hydrologic breakline product was delivered in ESRI shape file format and was also used in the processing of the DEM deliverable.
2015-05-11T00:00:00
Lidar deliverable processing
5
Tile Size: 5,000 ft x 5,000 ft. The tile file name was derived from the southwest corner of each tile.s
2015-05-11T00:00:00
Tile index and data extent
6
DEM data was received by NOAA/OCM from the City of Portland in Imagine format, State Plane NAD83(HARN) Maine West (zone 1802) with vertical feet referenced to NGVD29. NOAA converted the data vertical meters referenced to NAVD88. Conversion from NGVD29 to NAVD88 was done with gdal_translate and VDatum.
2017-03-16T00:00:00
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
7
Data were converted to vertical feet using gdal_translate to be consistent with the horizontal units. Data were also converted to cloud optimized geotiff format and given vertical georeferencing in the same step.
2023-08-15T00:00:00
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
gov.noaa.nmfs.inport:49410
Anne Ball
2017-11-15T15:13:00
Kirk Waters
2024-01-10T18:55:58
2024-01-10
OCM Partners
OCMP
1002
Public
No
2022-03-16
1 Year
2023-03-16