2015 NYSGPO Lidar: Warren, Washington, and Essex Counties, NY

Axis Geospatial has contracted Atlantic to obtain professional services related to the development of Light Detection and Ranging (LiDAR) data between April 2015 and June 2015. This data set is consisting of LiDAR Point Cloud, Classified LiDAR, Digital Elevation Model, and LiDAR Intensity Images which all pieces encompasses the entire 2,424 Square miles (6,278 km) of the NY_WarrenWashingtonEssex_Spring2015 project area. The project area spans 5 counties including Warren, Washington, Essex, Hamilton, and Franklin. This data set consists of LiDAR point cloud with nominal pulse spacing of 0.5557 m, and tiled Las files. Each LAS file contains LiDAR point information, which has been calibrated, controlled, and classified.

Ground Conditions: water at normal levels; no unusual inundation; no snow; leaf off

The calibrated point cloud data from the laser sensor was merged to produce processed (*.las) files including but not limited to 3D position, intensity, and time-stamp. A filtering methodology was utilized to produce a multi-return surface elevation model dataset with bare-earth conditions. GeoCue, TerraScan, and TerraModel software was used for the initial batch processing and manual editing of the (*.las) point clouds. The errors (noise columns) in classification were corrected by identifying the areas of dense noise in the point cloud and manually removing the incorrectly classified ground surfaces and above ground features.The Withheld and Overlap flags were utilized for the final LAS v1.4 file production. These classified LiDAR points were then used in the creation of other deliverables such as Bare-Earth Digital Elevation Models (DEMs) and LiDAR Intensity images. The final deliverables include 2783 tiles.

How the Withheld Points are Identified: Withheld (ignore) points were identified in the files using the standard LAS Withheld bit.

Class Code:0

Class Item: Never Classified

Class Code:1

Class Item: Undetermined/Unclassified

Class Code:2

Class Item: Ground

Class Code:7

Class Item:Low Point (Noise)

Class Code:17

Class Item:Bridge Deck

Class Code:18

Class Item:High Noise

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.

This LiDAR elevation data and its derivatives including high resolution Bare Earth DEMs and LiDAR Intensity imagery will be used for conservation planning, design, research, floodplain mapping, wetlands identification, dam safety assessments, hydrologic modelling, subsidence monitoring, and general spatial analyst.

All Lidar data was acquired, calibrated, and used in the creation of Lidar derived products by Atlantic.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "

USGS-NGP Base Lidar Specification v1.2

",

"ldrsens" : "

Leica ALS70-HP

",

"ldrmaxnr" : "

Unlimited

",

"ldrnps" : "

0.6

",

"ldrdens" : "

2.5

",

"ldranps" : "

0.5557

",

"ldradens" : "

3.24

",

"ldrfltht" : "

2260

",

"ldrfltsp" : "

125

",

"ldrscana" : "

40

",

"ldrscanr" : "

34.4

",

"ldrpulsr" : "

252.0

",

"ldrpulsd" : "

4

",

"ldrpulsw" : "

0.46

",

"ldrwavel" : "

1064

",

"ldrmpia" : "

1

",

"ldrbmdiv" : "

0.15

",

"ldrswatw" : "

1565

",

"ldrswato" : "

20

",

"ldrgeoid" : "

National Geodetic Survey (NGS) Geoid12A

"

},

"ldraccur" : {

"ldrchacc" : "

0.196

",

"rawnva" : "

0.074

",

"rawnvan" : "

290

",

"clsnva" : "

0.077

",

"clsnvan" : "

294

",

"clsvva" : "

0.099

",

"clsvvan" : "

379

"

},

"lasinfo" : {

"lasver" : "

1.4

",

"lasprf" : "

6

",

"laswheld" : "

Withheld (ignore) points were identified in the files using the standard LAS Withheld bit.

",

"lasolap" : "

Swath overage points were identified in these files using the standard LAS overlap bit.

",

"lasintr" : "

32

",

"lasclass" : {

"clascode" : "0",

"clasitem" : "Never Classified"

},

"lasclass" : {

"clascode" : "1",

"clasitem" : "Undetermined/Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Deck"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

LiDAR Tiles and associated derived products for Axis Geospatial New York AOI

The data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose.

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

Data is available online for bulk and custom downloads.

None

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.

CloudPro 1.2.0 Build 85620; GeoCue Version 2014.1.21.2; Windows 7 Operating System

Horizontal error in lidar derived elevation data is largely a function of positional error as derived from the Global Navigation Satellite System (GNSS), attitude (angular orientation) error (as derived from the INS) and flying altitude; and can be estimated based on these parameters. As described in Section 7.5 of the ASPRS Positional Accuracy Standards for Digital Geospatial Data the horizontal errors in lidar data are largely a function of GNSS positional error, INS angular error, and flying altitude. Therefore lidar data collected with GNSS error of 0.05m and the IMU error of 0.03492 degrees at an altitude of 2300m; the expected radial horizontal positional error will be RMSEr = 0.130 m.

Vertical Accuracy of the point cloud and bare-earth lidar data was assessed and reported in accordance with the ASPRS Positional Accuracy Standards for Digital Geospatial Data;

Six-Hundred and Seventy-Three (673) surveyed points were measured for the purpose of assessing the accuracy of the NY_WarrenWashingtonEssex_Spring2015 project data. (294 NVA + 379 VVA). Both data sets, Lidar and Digital Elevation Models (DEMs) have been tested for individual vertical accuracy levels. The Lidar was tested by using interpolation while the DEMs where tested by extracting the elevation of a pixel containing the checkpoint. All DEM Vertical accuracy results are reported in the DEM metadata reports while this project wide metadata file is reporting the vertical accuracy results from the the source Lidar. This data set was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10.0 (cm) RMSEz Vertical Accuracy Class.

Actual NVA accuracy of the classified point cloud was found to be RMSEz = 0.077 m, equating to +/- 0.152 m at 95% confidence level.

Actual VVA accuracy was found to be RMSEz = 0.099 m, equating to +/- 0.178 m at 95% confidence level.

The raw LAS data files included all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Fundamental Vertical Accuracy specifications.Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header.

Aerial LiDAR data covers the entire 2,424 square mile area for the NY_WarrenWashingtonEssex_Spring2015 project task. All LiDAR Point Cloud tiles show no edge artifacts or mismatches from tile to tile. Void areas (i.e. areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header. Data cover the entire area specified for this project.

Data is backed up to tape and to cloud storage.

Data were collected and processed by Atlantic for the New York State GIS Program Office (NYSGPO) and posted to their ftp site. The NOAA Office for Coastal Management (OCM) downloaded the data from the ftp site and processed it to make it available for custom download from the Data Access Viewer (DAV) and bulk download from https.