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Summary
Item Identification
Keywords
Physical Location
Data Set Info
Support Roles
Extents
Spatial Info
Access Info
Distribution Info
URLs
Data Quality
Data Management
Lineage
Related Items
Catalog Details

Summary

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Short Citation
OCM Partners, 2024: 2022 City of Philadelphia Lidar DEM: Philadelphia, PA, https://www.fisheries.noaa.gov/inport/item/70174.
Full Citation Examples

Abstract

This dataset is raster digital elevation model (DEM) data covering the City of Philadelphia, PA. The data were collected for the City of Philadelphia in April 2022. DEMs were generated from the raw data. This lidar point cloud data covers approximately 239 square miles total. At the time of capture ground conditions were leaf-off, snow free, and water was at normal levels.

The lidar mapping requirements and deliverables meet Quality Level One (QL1) standards for final deliverables as outlined in the USGS-NGP Lidar Base Specification 2021, Revision A (https://www.usgs.gov/3DEP/lidarspec). QL1 lidar specifications suggest a pulse density of greater than or equal to 8 pulses per square meter Aggregate Nominal Pulse Density (ANPD), and pulse spacing of less than or equal to 35 centimeters Aggregate Nominal Pulse Spacing (ANPS). Additionally, lidar capture over the city center has increased point density of 16 ppsm.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV).

The NOAA Office for Coastal Management (OCM) downloaded 1 raster DEM file in GeoTiff format from the PASDA (Pennsylvania Spatial Data Access) site.

The data were processed to the NOAA Digital Coast Data Access Viewer (DAV) to make the data available for bulk and custom downloads. In addition to these bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEM data were created from, are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

Distribution Information

  • 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.

  • GeoTIFF

    Bulk download of data files in Pennsylvania South State Plane NAD83(2011) US Survey Feet coordinates and elevations in NAVD88 (Geoid18) feet.

Access Constraints:

None

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.

Controlled Theme Keywords

COASTAL ELEVATION, DIGITAL ELEVATION/TERRAIN MODEL (DEM), elevation, TERRAIN ELEVATION

Child Items

No Child Items for this record.

Contact Information

Point of Contact
NOAA Office for Coastal Management (NOAA/OCM)
coastal.info@noaa.gov
(843) 740-1202

Metadata Contact
NOAA Office for Coastal Management (NOAA/OCM)
coastal.info@noaa.gov
(843) 740-1202

Extents

Geographic Area 1

-75.337789° W, -74.939567° E, 40.158785° N, 39.81252° S

Time Frame 1
2022-03-29

Item Identification

Title: 2022 City of Philadelphia Lidar DEM: Philadelphia, PA
Status: Completed
Creation Date: 2022
Publication Date: 2022
Abstract:

This dataset is raster digital elevation model (DEM) data covering the City of Philadelphia, PA. The data were collected for the City of Philadelphia in April 2022. DEMs were generated from the raw data. This lidar point cloud data covers approximately 239 square miles total. At the time of capture ground conditions were leaf-off, snow free, and water was at normal levels.

The lidar mapping requirements and deliverables meet Quality Level One (QL1) standards for final deliverables as outlined in the USGS-NGP Lidar Base Specification 2021, Revision A (https://www.usgs.gov/3DEP/lidarspec). QL1 lidar specifications suggest a pulse density of greater than or equal to 8 pulses per square meter Aggregate Nominal Pulse Density (ANPD), and pulse spacing of less than or equal to 35 centimeters Aggregate Nominal Pulse Spacing (ANPS). Additionally, lidar capture over the city center has increased point density of 16 ppsm.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV).

The NOAA Office for Coastal Management (OCM) downloaded 1 raster DEM file in GeoTiff format from the PASDA (Pennsylvania Spatial Data Access) site.

The data were processed to the NOAA Digital Coast Data Access Viewer (DAV) to make the data available for bulk and custom downloads. In addition to these bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEM data were created from, are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

Purpose:

To provide QL1 elevation data to the City of Philadelphia Office of Innovation and Technology.

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
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 > PENNSYLVANIA
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
Airplane > Airplane

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:

The USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.

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: City of Philadelphia Office of Innovation and Technology, Merrick

Support Roles

Data Steward

CC ID: 1257087
Date Effective From: 2023
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: 1257086
Date Effective From: 2023
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: 1257088
Date Effective From: 2023
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: 1257089
Date Effective From: 2023
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: 1299421
W° Bound: -75.337789
E° Bound: -74.939567
N° Bound: 40.158785
S° Bound: 39.81252

Extent Group 1 / Time Frame 1

CC ID: 1299420
Time Frame Type: Discrete
Start: 2022-03-29

Spatial Information

Spatial Representation

Representations Used

Grid: Yes
Vector: No
Text / Table: No
TIN: No
Stereo Model: No
Video: No

Reference Systems

Reference System 1

CC ID: 1299417

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: 1299418

Coordinate Reference System

CRS Type: Projected
EPSG Code: EPSG:6565
EPSG Name: NAD83(2011) / Pennsylvania South (ftUS)
See Full Coordinate Reference System Information

Access Information

Security Class: Unclassified
Data Access Procedure:

Data is available online for bulk or 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: 1257090
Start Date: 2023-05-19
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9849/details/9849
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2023 - 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 (Deprecated): Zip
Compression: Zip

Distribution 2

CC ID: 1257091
Start Date: 2023-05-19
End Date: Present
Download URL: https://noaa-nos-coastal-lidar-pds.s3.us-east-1.amazonaws.com/dem/PA_Phil_DEM_2022_9849/index.html
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2023 - Present)
File Name: Bulk Download
Description:

Bulk download of data files in Pennsylvania South State Plane NAD83(2011) US Survey Feet coordinates and elevations in NAVD88 (Geoid18) feet.

File Type (Deprecated): GeoTIFF
Distribution Format: GeoTIFF

URLs

URL 1

CC ID: 1257093
URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9848/details/9848
Name: Custom DEM Download
URL Type:
Online Resource
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 2

CC ID: 1257094
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 3

CC ID: 1257095
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9848/supplemental/pa2022_phil_m9848.kmz
Name: Browse graphic
URL Type:
Browse Graphic
File Resource Format: KML
Description:

This graphic displays the footprint for this lidar data set.

URL 4

CC ID: 1257097
URL: https://www.pasda.psu.edu/download/phillyLiDAR/2022/Metadata_and_Reports/Lidar_Report/65221207_Philadelphia_Mapping_Report.pdf
Name: Merrick Lidar Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to the Merrick lidar report.

URL 5

CC ID: 1257098
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9848/breaklines/index.html
Name: Hydro Breaklines
URL Type:
Online Resource
File Resource Format: Zip
Description:

Link to the hydro breaklines.

Data Quality

Vertical Positional Accuracy:

After hand-filtering has been completed and quality checked, a Checkpoint Report is generated to validate that the accuracy of the ground surface is within the defined accuracy specifications. Each surveyed ground check point is compared to the lidar surface by interpolating an elevation from a Triangulated Irregular Network (TIN) of the surface. The MARS derived report provides an in-depth statistical report, including an RMSE of the vertical errors; a primary component in most accuracy standards and a statistically valid assessment of the overall accuracy of the ground surface.

Based on 51 ground survey checkpoints, this dataset was tested to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10.0 cm RMSEz Vertical Accuracy Class.

Actual DEM NVA accuracy was found to be RMSEz = 2.348 cm

Actual DEM VVA accuracy was found to be plus or minus 9.931 cm at the 95th percentile

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:

Data were collected and processed by Merrick for the City of Philadelphia Office of Innovation and Technology and were made available on the PASDA site. The data were downloaded from the PASDA site by the NOAA Office for Coastal Management (OCM) where the data were processed to make it available for custom download from the NOAA Digital Coast Data Access Viewer (DAV) and for bulk download from https.

Sources

PASDA

CC ID: 1299410
Contact Role Type: Publisher
Contact Type: Organization
Contact Name: PASDA
Citation URL: https://www.pasda.psu.edu/download/phillyLiDAR/2022/Products/
Citation URL Name: Philadelphia Lidar DEM PASDA Link

Process Steps

Process Step 1

CC ID: 1299411
Description:

Lidar acquisition was collected using fixed wing aircraft and two Optech Galaxy T2000 lidar sensors staging from a variety of airports around the project area. Up to eight return values are recorded for each pulse which ensures the greatest chance of ground returns in a heavily forested area. Lidar data collection was accomplished on March 29, 2022 (dates listed are in local time NOT UTC). Each mission represents a lift of the aircraft and system from the ground, collects data, and lands again. Multiple lifts within a day are represented by Mission A, B, C, and D.

Process Date/Time: 2022-03-29 00:00:00

Process Step 2

CC ID: 1299412
Description:

GNSS/IMU Data

A five-minute IMU initialization is conducted on the ground, with the aircraft engines running, prior to flight, to establish fine alignment of the IMU. In air IMU calibration maneuvers were performed at the beginning and ending of all mission collections to ensure the best forward and reverse trajectory processing using the highest quality IMU calibration. During the data collection, the operator recorded information on log sheets which includes weather conditions, lidar operation parameters, and flight line statistics. Data is sent back to the main office for preliminary processing to check overall quality of GNSS / IMU data and to ensure sufficient overlap between flight lines. Any problematic data may be reflown immediately as required. The airborne GNSS data was post-processed using Applanix POSPac Mobile Mapping Suite version 8.x. A fixed bias carrier phase solution was computed in both the forward and reverse chronological directions. Whenever practical, lidar acquisition was limited to periods when the PDOP was less than 4.0. PDOP indicates satellite geometry relating to position. Generally, PDOPs of 3.0 or less result in a good quality solution, however PDOPs between 3.0 and 5.0 can still yield good results most of the time. PDOPs over 6.0 are of questionable results and PDOPs of over 7.0 usually result in a poor solution. Usually as the number of satellites increase the PDOP decreases. Other quality control checks used for the GNSS include analyzing the combined separation of the forward and reverse GNSS processing from one CORS station and the results of the combined separation when processed from two different CORS stations. An analysis of the number of satellites, present during the flight and data collection times, is also performed. The GNSS trajectory was combined with the raw IMU data and post-processed using POSPac Mobile Mapping Suite version 8.x. The SBET and refined attitude data are then utilized in the Optech LMS lidar processing software to compute the laser point-positions. The trajectory is combined with the laser range measurements to produce lidar point cloud data.

GNSS Controls

Virtual Ground GNSS Base Station(s) were used to control the lidar airborne flight lines. Post processed Trimble CenterPoint RTX correction service is a high-accuracy, satellite-delivered global positioning service. This technology provides high accuracy GNSS positioning without the use of traditional reference station based differential RTK infrastructure and delivers very high cm level accuracy. In addition, CORS are at times used to further QC or enhance the airborne GNSS solution.

Lidar Calibration

Merrick takes great care to ensure all lidar acquisition missions are carried out in a manner conducive to postprocessing an accurate dataset. Proper Airborne GNSS surveying techniques are always followed including pre- and post-mission static initializations. In-air IMU alignments (figure-eights) are performed both before and after on-site collection to ensure proper calibration of the IMU accelerometers and gyros. A minimum of one cross-flight is planned throughout the project area across all flightlines and over roadways where possible. The cross-flight provides a common control surface used to remove any vertical discrepancies in the lidar data between flightlines. The cross-flight is critical to ensure flightline ties across the project area. The areas of overlap between flightlines are used to boresight (calibrate) the lidar point cloud to achieve proper flightline to flightline alignment in all three axes. Each lidar mission flown is accompanied by a hands-on boresight in the office. After boresighting is complete a detailed statistical report is generated to check relative and absolute accuracies before filtering of lidar begins.

Process Date/Time: 2022-01-01 00:00:00

Process Step 3

CC ID: 1299413
Description:

The lidar filtering process encompasses a series of automated and manual steps to classify the boresighted point cloud data set. Each project represents unique characteristics in terms of cultural features (urbanized vs. rural areas), terrain type and vegetation coverage. These characteristics are thoroughly evaluated at the onset of the project to ensure that the appropriate automated filters are applied and that subsequent manual filtering yields correctly classified data. Data is most often classified by ground and unclassified, but specific project applications can include a wide variety of classifications including but not limited to buildings, vegetation, power lines, etc. A variety of software packages are used for the auto-filtering, manual filtering and QC of the classified data.

Merrick used the ASPRS LAS Specification Version 1.4 R15 (ASPRS, 2011, published 09 July 2019), Point Data Record Format 6 for this project and classified the lidar point cloud in accordance with the following classification classes and bitflags.

Merrick has developed several customized automated filters that are applied to the lidar data set based on project specifications, terrain, and vegetation characteristics. A filtering macro, which may contain one or more filtering algorithms, is executed to derive LAS files separated into the different classification groups as defined in the ASPRS classification table. The macros are tested in several portions of the project area to verify the appropriateness of the filters. Often, there is a combination of several filter macros that optimize the filtering based on the unique characteristics of the project. Automatic filtering generally yields a ground surface that is 85 - 90% valid, so additional editing (hand-filtering) is required to produce an accurate ground surface. Lidar data is next taken into a graphic environment using MARS to manually re-classify (or hand-filter) noise and other features that may remain in the ground classification after auto filter. A cross-section of the post auto-filtered surface is viewed to assist in the reclassification of non-ground data artifacts. The following is an example of re-classification of the non-ground points (elevated features) that need to be excluded from the true ground surface. Certain features such as berms, hilltops, cliffs and other features may have been aggressively auto-filtered and points will need to be re-classified into the ground classification. Data in the profile view displays non-ground (Unclassified, class 1) in grey and ground in brown/tan (Class 2). At this point, individual lidar points from the original point cloud have now been parsed into separate classifications.

Process Date/Time: 2022-01-01 00:00:00

Process Step 4

CC ID: 1299414
Description:

After hand-filtering has been completed and quality checked, a Checkpoint Report is generated to validate that the accuracy of the ground surface is within the defined accuracy specifications. Each surveyed ground check point is compared to the lidar surface by interpolating an elevation from a Triangulated Irregular Network (TIN) of the surface. The MARS derived report provides an in-depth statistical report, including an RMSE of the vertical errors; a primary component in most accuracy standards and a statistically valid assessment of the overall accuracy of the ground surface.

Process Date/Time: 2022-01-01 00:00:00

Process Step 5

CC ID: 1299415
Description:

Hydro - flattening breaklines are captured per the USGS-NGP Lidar Base Specification 2021, Revision A. Final hydro-flattened breaklines features are appropriately turned into polygons (flat elevations) and polylines (decreasing by elevation) and are used to reclassify ground points in water to water (Class 9). The lidar points around the breaklines are reclassified to ignored ground (Class 20) based on the planned collected point density. The next step in the process is the hydro-flattening breakline collection required for the development of the hydro-flattened DEMs. Merrick will capture hydro-flattening breaklines for waterbodies greater than or equal to approximately eight-tenths (~0.8) hectare (e.g., ~100-meter diameter); double-sided streams and rivers that are greater than or equal to 30 meters in (nominal) width, and; any visible islands greater than or equal to approximately four-tenths (~0.4) hectare. Criteria for Non-Tidal Boundary Waters and Tidal Waters are assumed not applicable. No single-line streams or drainages will be collected, nor will any planimetric features that could be utilized as traditional breaklines. All downstream hydro-flattening breaklines require monotonicity (e.g., streams and rivers). Closed polygonal boundaries of water will maintain a fixed (i.e., flat) elevation.

Process Step 6

CC ID: 1299416
Description:

The NOAA Office for Coastal Management (OCM) downloaded 1 raster DEM file in GeoTiff format from this PASDA site:

https://www.pasda.psu.edu/download/phillyLiDAR/2022/Products/

The data were in Pennsylvania State Plane South (NAD83 2011), US survey feet coordinates and NAVD88 (Geoid18) elevations in feet. The bare earth hydro-flattened file was at a 3 ft grid spacing. OCM converted the raster file to a cloud optimized file in GeoTiff format for Digital Coast storage and provisioning purposes.

Process Date/Time: 2023-06-16 00:00:00
Process Contact: Office for Coastal Management (OCM)

Related Items

Item Type Relationship Type Title
Data Set (DS) Cross Reference 2022 City of Philadelphia Lidar: Philadelphia, PA

Catalog Details

Catalog Item ID: 70174
GUID: gov.noaa.nmfs.inport:70174
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2023-06-16 18:15+0000
Metadata Record Last Modified By: Kirk Waters
Metadata Record Last Modified: 2024-01-10 19:30+0000
Metadata Record Published: 2024-01-10
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2023-05-19
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2024-05-19