2011 U.S. Geological Survey Topographic LiDAR: LiDAR for the North East

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

Simple download of data files in geographic coordinates. Vertical datum is NAVD88 instead of ellipsoid.

This graphic shows the lidar coverage for the coastal regions of ME, MA, NH, RI, CT and NY.

A map showing the Nominal Point Spacing for each area of the project

A map showing the Vertical Accuracy for each area of the project

Original metadata for the State of Massachusetts

Original metadata for the State of Connecticut (UTM Zone 18)

Original metadata for the State of Connecticut (UTM Zone 19)

Original metadata for the State of New York

Original metadata for the State of New Hampshire

Original metadata for the State of Rhode Island

Original metadata for the State of Maine

Date that the source FGDC record was last modified.

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.

Partial upload of Positional Accuracy fields only.

Partial upload to move data access links to Distribution Info.

Control Process:

James W. Sewall Company was contracted by Photo Science, Inc. to locate a total of 156 calibration control points (60 for MA, 31 for NY, 11 for CT18,

4 for CT19, 25 for NH and 25 for RI) used in the post processing of the LiDAR data as well as 20 quality assurance check points for each state. The points

were located on relatively flat terrain on surfaces that generally consisted of grass, gravel or bare earth. See Final Survey Reports for

additional collection parameters and methodologies.

Raw Flight Line Process:

Applanix software was used in the post processing of the airborne GPS and inertial data that is critical to the

positioning and orientation of the sensor during all flights. POSPac MMS provides the smoothed best estimate of trajectory (SBET) that is

necessary for Optech's post processor to develop the point cloud from the LiDAR missions. The point cloud is the mathematical three dimensional

collection of all returns from all laser pulses as determined from the aerial mission. At this point this data is ready for analysis,

classification, and filtering to generate a bare earth surface model in which the above ground features are removed from the data set. The point

cloud was manipulated within the Optech or Leica software; GeoCue, TerraScan, and TerraModeler software was used for the automated data classification,

manual cleanup, and bare earth generation from this data. Project specific macros were used to classify the ground and to remove the side overlap

between parallel flight lines.

All data was manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler.

Classified LAS Process:

All ground (ASPRS Class 2) LiDAR data inside of the Lake Pond and Double Line Drain hydro flattening breaklines were then classified to water

(ASPRS Class 9) using TerraScan macro functionality. A buffer of 1 meter 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 Double Line Drain Island features were

checked to ensure that the ground (ASPRS Class 2) were reclassified to the correct classification after the automated classification was completed.

A new class has been added to the dataset to represent the bare water of the ocean areas collected throughout the project area. ASPRS Class 14 is

being used to represent the bare water ocean surface. While attempts were made to remove all extraneous features above the surface of the water, there

may be above surface features classified to this class. Some islands below the required collection specifications have been classified to this class as

well. This class was also used during the creation of the ERDAS Imagine Raster DEM files. The Ocean Shoreline and Ocean Island breaklines were used to

complete the automated classification of these classes within the final LAS files.

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 to Class 17 (USGS Overlap Default), Class 18 (USGS Overlap Ground), Class 25 (USGS Overlap Water), and Class 30

(USGS Overlap Bare Water). These classes were created through automated processes only and were not verified for classification accuracy. Due to software

limitations within TerraScan, these classes were used to trip the Withheld bit within various software packages. These processes were reviewed and accepted

by USGS through multiple conference calls and pilot study areas.

Data was then run through additional macros to ensure deliverable classification levels matching the ASPRS LAS Version 1.2 Classification structure. GeoCue

functionality was then used to ensure correct LAS Versioning. In-house software was used as a final QA/QC check to provide LAS Analysis of the delivered tiles.

QA/QC checks were performed on a per tile level to verify final classification metrics and full LAS header information.

Hydro Flattening Breakline Process:

Class 2 LiDAR was used to create a bare earth surface model. The surface model was then used to heads-up digitize 2D breaklines of inland streams and rivers

with a 30 meter nominal width and Inland Ponds and Lakes of 8,000 sq. meters or greater surface area.

Ocean Shoreline and Ocean Island features were collected at appropriate elevations on an overall review of the surface models to determine the land water breaklines.

These features were used to determine the classification within the Classified LAS files. These features can be used to represent a flat water surface, but were not

run through the same project quality control procedures as the inland water body features. Elevation differences between ocean shoreline and ocean islands will be found.

This is due in large part to the coastal water elevation changes, found between missions, as well as flightline to flightline.

Elevation values were assigned to all Inland Ponds and Lakes, Inland Pond and Lake Islands, Inland Stream and River Islands, Ocean Shoreline and Ocean Islands using

TerraModeler functionality.

Elevation values were assigned to all Inland streams and rivers using Photo Science proprietary software.

All ground (ASPRS Class 2) LiDAR data inside of the collected inland breaklines were then classified to water (ASPRS Class 9) using TerraScan macro functionality. A buffer

of 1 meter was also used around each hydro flattened feature. These points were moved from ground (ASPRS Class 2) to Ignored Ground (ASPRS Class 10).

The breakline files were then translated to ESRI Shapefile format using ESRI conversion tools.

Raster DEM Process:

Using automated scripting routines within ArcMap, the ground (ASPRS Class 2) and bare water (USGS Class 14) were combined with the Hydro Flattened Breaklines (excluding

the Ocean Shoreline and Ocean Island line types) to create the 1 meter DEM. Final DEM tiles were clipped to the project tile boundary to provide a seamless dataset.

ERDAS IMG files were then created as the project deliverable.

A manual QA review of the tiles was completed in ArcMap and Global Mapper to ensure full coverage with no gaps or slivers within the project area.

The NOAA Office for Coastal Management (OCM) received the topographic files in .LAS format from USGS and the Maine Office of GIS. The classified .LAS files contained lidar elevation and intensity measurements. The data were received in UTM Zone 18N/19N, NAD83 coordinates and were vertically referenced to NAVD88 using the Geoid09 model. The vertical units of the data were meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. The topographic .LAS files were compressed using LAStools' laszip software.

2. The topographic .LAS files were converted from a Projected Coordinate System (UTM Zone 18N/19N) to a Geographic Coordinate system (NAD83).

3. The topographic .LAS files were converted from orthometric NAVD88 to NAD83 ellipsoidal heights using Geoid09.