New York Office of Information Technology Services
Unpublished Material
Southwest 17 - Spring, New York Lidar; Classified Point Cloud
Lidar point cloud
Product: Calibrated LiDAR version 1.4 .las tiles, classified to bare earth for subsequent derivatives.
Geographic Extent: Chautauqua and Cattaraugus County, New York, covering approximately 1,722 square miles.
Dataset Description: Chautauqua and Cattaraugus County, New York 2017 Lidar project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.7 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83(2011), Universal Transverse Mercator Zone 17 N, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS 1.4 files, formatted to 1982 individual 1500 m x 1500 m tiles, as tiled bare earth DEMs; all tiled to the same 1500 m x 1500 m schema.
Ground Conditions: Lidar was collected in early 2017, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, New York Office of Information Technology Services established a total of 32 ground control points that were used to calibrate the lidar to known ground locations established throughout the Chautauqua and Cattaraugus County, New York project area. An additional 128 independent accuracy checkpoints, 75 in Bare Earth and Urban landcovers (75 NVA points). 53 in Tall Grass and Brushland/Low Trees categories (53 VVA points) were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.
To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 1 meter cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, hydro-flattened DEMs as necessary.
USGS Contract No. G17AC00096 CONTRACTOR: New York Office of Information Technology Services. SUBCONTRACTOR: Axis Geospatial, LLC Lidar data were acquired and calibrated by Axis GeoSpatial, LLC. All follow-up processing was completed by the prime contractor. This material is based upon work supported by the Natural Resources Conservation Service, U.S. Department of Agriculture, under number 68-2C31-17-099.
USGS-NGP Base Lidar Specification v1.2
Riegl Q1560 LiDAR System (Axis GeoSpatial LLC)
7
.76
2.87
.71
2.0
2469
145
58.52
84.3
766
5
.60
1064
1
0.25
2561
20
NAD 1983(2011) UTM Zone 17N Meters
National Geodetic Survey (NGS) Geoid12B
0.3887
0.048
75
1.4
6
Withheld (ignore) points were identified in these files using the standard LAS Withheld bit.
Swath "overage" points were identified in these files using the standard LAS overlap bit.
16
1
Processed, but Unclassified
2
Bare Earth Ground
7
Low Noise
9
Water
10
Ignored Ground
17
Bridge Decks
18
High Noise
20170418
20170509
ground condition
None planned
-79.768477
-78.718362
42.581543
41.985952
None
LAS Point Cloud
Elevation Data
Lidar
None
New York
Chautauqua County
Cattaraugus County
No restrictions apply to these 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 the limitations of the data. Acknowledgement of New York Office of Information Technology Services would be appreciated for products derived from these data. The data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of the 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.
Data covers the entire area specified for this project.
These LAS data files include 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 Non-Vegetated Vertical Accuracy specifications. Points with extreme elevations (negative values, or positive values well above the expected maximum) are present in this dataset. These points are classified as low or high noise in classified point cloud tiles.
LAS Point Classification: The point classification is performed as described below. The bare earth surface is manually reviewed to ensure correct classification on the Class 2 (Ground) points. After the bare-earth surface is finalized, it is then used to generate all hydro-breaklines through digitization. All ground (ASPRS Class 2) lidar data inside of 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) points were reclassified to the correct classification after the automated classification was completed. All overlap data was processed through automated functionality provided by LasTools to appropriately bit flag overlapping flight line data per USGS specifications. All data was manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler. Global Mapper was used as a final check of the bare earth dataset. LP360 was then used to create the deliverable industry-standard LAS files for both the All Point Cloud Data and the Bare Earth. New York Office of Information Technology Services proprietary software was used to perform final statistical analysis of the classes in the LAS files, on a per tile level to verify final classification metrics and full LAS header information.
2017
Point
Universal Transverse Mercator
17
0.9996
-81.00
0.0
500000
0.0
coordinate pair
0.01
0.01
meters
North American Datum of 1983 (2011)
Geodetic Reference System 80
6378137
298.257222101
North American Vertical Datum of 1988 (Geoid12B)
0.01
meters
Explicit elevation coordinate included with horizontal coordinates
20171115
New York Office of Information Technology Services
mailing and physical
10B Airline Drive
Albany
NY
12235
USA
(518)242-5061
FGDC Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998