2018 NYS Lidar: Cayuga and Oswego Counties, NY

Product: Calibrated LiDAR version 1.4 .las tiles, classified to bare earth for subsequent derivatives.

Geographic Extent: Cayuga and Oswego County, New York, covering approximately 1,720 square miles.

Dataset Description: Cayuga and Oswego County, New York 2018 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 1.3. The data was developed based on a horizontal projection/datum of NAD83(2011), Universal Transverse Mercator Zone 18 N, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 1,980 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 the spring 2018, 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 48 ground control points that were used to calibrate the lidar to known ground locations established throughout the Cayuga and Oswego County, New York project area. An additional 125 independent accuracy checkpoints, 69 in Bare Earth and Urban landcovers (69 NVA points). 56 in Tall Grass and Brushland/Low Trees categories (56 VVA points) were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

The NOAA Office for Coastal Management (OCM) downloaded this data set from this USGS site:

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects

Folders downloaded:

1. USGS_LPC_NY_CayugaOswego_2018_LAS_2019/ Number of files: 1921

2. USGS _LPC_NY_CayugaOswego_TL_2018_LAS_2019/ Number of files: 124

These files were processed to the Data Access Viewer (DAV) and https. The total number of files downloaded and processed was 2045.

Hydro breaklines are also available. These data are available for download at the link provided in the URL section of this metadata record. Please note that these products have not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

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, 3D breaklines, hydro-flattened DEMs as necessary.

USGS Contract No. G18AC00040 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.

Any conclusions drawn from the analysis of this information are not the responsibility of Axis Geospatial, LLC, New York Office of Information Technology Services, USGS, NOAA, the Office for Coastal Management or its partners.

Data is available online for bulk and custom downloads.

None

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.

Non-Vegetated Vertical Accuracy (NVA) Check Points and Vegetated Vertical Accuracy (VVA) Check Points were independently surveyed and compared to the DEM data. For the NVA checkpoints, the overall RMSEz is 3.1 centimeters. This compares favorably to the USGS specification of < 10 cm. (USGS “LiDAR Base Specification vers. 1.3”, Page 4, Table 4;). The NVA at the 95% confidence level is 6.1 centimeters which is within the USGS specification of < 19.6 cm. (USGS “LiDAR Base Specification vers. 1.3”, Page 24, Table 4;)

Vegetated Vertical Accuracy (VVA) Check Point RMSEz is 6.6 centimeters and the VVA at the 95th percentile is 11.9 centimeters. The USGS specification for VVA at the 95th percentile is < 29.4 cm. (USGS “LiDAR Base Specification vers.1.3”, Page 24, Table 4;)

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. You may see data voids where caused by areas of low near infrared reflectivity, such as asphalt or composition roofing. We have seen these dropouts on building rooftops throughout this project. Also, there are extreme positive and negative Z values within the LiDAR pointcloud. We have classified these points as Class 7 (Low Point) and/or Class 18 (High Point) to accommodate for these values. Partially elevated water bodies may be present where use of Class 20 (Ignored Ground) next to the hydro breaklines has eliminated ground points on a small berm or raised bank.

Data covers the entire area specified for this project except there is a known data gap on the southeast corner of tile 4335081050. Partially elevated water bodies may be present where use of Class 20 (Ignored Ground) next to the hydro breaklines has eliminated ground points on a small berm or raised bank.

Data is backed up to tape and to cloud storage.