New York USDA NRCS
20130125
High Resolution Digital Lidar Data Acquisition and Processing for portions of Lewis County, New York
v.01
map
LiDAR
1
Syracuse, NY
New York USDA NRCS
This data has been acquired and developed by the USDA-NRCS New York to collect and deliver topographic elevation point data derived from multiple return light detection and ranging (LiDAR) measurements for the 400 sq. mile project area. Fugro EarthData, Inc. acquired 59 flight lines in 5 lifts from November 5, 2011 to November 8, 2011. LiDAR data collection was performed with a Cessna 310 twin engine aircraft, utilizing a Leica ALS60 MPiA sensor; collecting multiple return x, y, and z as well as intensity data. The LiDAR point cloud data are delivered in LAS 1.2 format as a classified point cloud containing the following classes: 1 - unclassified, 2 - ground, 7 - low points, 8 - model keypoints, 9 - water, and 12 - overlap points; as model key LAS; as first return LAS; and as last return LAS. Specialized in-house and commercial software processes the native LiDAR data into 3-dimensional positions that can be imported into GIS software for visualization and further analysis. The horizontal datum for the data is the UTM Zone 18 North Coordinates, NAD83(2007) in meters and the vertical datum is the North American Vertical Datum of 1988 (NAVD88) in meters using GEIOD09.
To acquire, process and store multiple-return LiDAR calibrated and classified point cloud data using compliant LAS 1.2 format with the following collection conditions: during leaf-off conditions, free of snow with rivers near average heights. Free of environmental conditions such as rain, fog or smoke.
The information in this report is the result of LiDAR surveys performed on the date indicated and the general conditions at the time of flight.
20111105
20111108
ground condition
As needed
-75.723630
-75.259667
44.018851
43.476669
Keywords
LiDAR
Terrain
Model
Elevation
Surface
Geographic Names Information System
US
New York
Lewis County
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be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions.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.
New York USDA NRCS
mailing and physical address
441 S. Salina St., Suite 354
Syracuse
New York
13202
USA
315.477.6525
cathy.crotty@ny.usda.gov
9:00am - 5:00pm
New York USDA NRCS
None
Unclassified
N/A
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.6.1500
During LiDAR data collection the airborne GPS receiver was collecting data at 2 Hz frequency and the Dilution of Precision (PDOP) was monitored. One GPS base station was also running at the operation airport and was recording data at 1 Hz. The airborne GPS data was post-processed in DGPS mode together with the base station data to provide high accuracy aircraft positions. The GPS trajectory then was combined with the IMU data using loosely coupled approach to yield high accuracy aircraft positions and attitude angles. Then the LiDAR data was processed using the aircraft trajectory and raw LiDAR data. After boresighting the LiDAR data, the ground control points were measured against the LiDAR data by technicians using TerraScan and proprietary software and the LiDAR data was adjusted vertically to the ground control. Independent ground control check points were used to ensure vertical accuracy of the data. The horizontal datum for the data is the UTM Zone 18 North Coordinates, NAD83(2007) in meters and the vertical datum is the North American Vertical Datum of 1988 (NAVD88) in meters. The vertical datum was realized through the use of the published/calculated ellipsoidal heights of the base station to process the aircraft trajectory and then later applying the GEOID09 model to the processed LiDAR data to obtain orthometric heights.
Compliance with the accuracy standard was ensured by the collection of ground control and the establishment of a GPS base station at the operation airport. The following checks were performed: 1) The LiDAR data accuracy was validated by performing a full boresight adjustment and then checking it against the ground control prior to generating a digital terrain model (DTM) or other products. 2) LiDAR elevation data was validated through an inspection of edge matching and visual inspection for quality (artifact removal).
The following methods are used to ensure LiDAR data accuracy: 1) Use of a ground control network utilizing GPS survey techniques; 2) Use of airborne GPS and IMU in conjunction with the acquisition of LiDAR; and 3) Measurement of quality control ground survey points within the finished product. The following software is used for the validation: 1) Terrascan and 2) Fugro EarthData Proprietary Software.
The minimum expected horizontal accuracy was tested to meet or exceed 0.6 m RMSE (Accuracyr = 1.04 m at the 95% confidence level).
The minimum expected horizontal accuracy was tested to meet or exceed 9.2 cm RMSE (Accuracyz = 0.18m at the 95% confidence level).
Fugro EarthData, Inc.
20111121
Aerial Acquisition of Lewis County, NY LiDAR
External hard drive
20111105
20111108
ground condition
Aerial LiDAR Acquisition
Fugro EarthData, Inc. collected ALS60-derived LiDAR over the project area with a 0.7 meter, nominal post spacing using a Cessna 310 twin engine aircraft. The collection for the entire project area was accomplished between November 5, 2011 and November 8, 2011; 59 flight lines were acquired in 5 lifts. The lines were flown at an average of 5,950 feet above mean terrain using a pulse rate of 150,000 pulses per second. The collection was performed using Leica ALS60 MPiA LiDAR systems, serial number 142.
TerraSurv
20120325
Report of Control Survey Lewis county, New York
electronic mail system
20111122
20111123
Ground Condition
Ground Control
TerraSurv under contract to Fugro EarthData, Inc. successfully established ground control for the Project. A total of 17 ground control points were acquired. GPS was used to establish the control network. The horizontal datum for the data is the UTM Zone 18 North, NAD83(2007) in meters and the vertical datum is the North American Vertical Datum of 1988 (NAVD88) in meters using GEIOD09.
All acquired LiDAR data went through a preliminary review to assure that complete coverage was obtained and that there were no gaps between flight lines before the flight crew left the project site. Once back in the office, the data is run through a complete iteration of processing to ensure that it is complete, uncorrupted, and that the entire project area has been covered without gaps between flight lines. There are essentially three steps to this processing: 1) GPS/IMU Processing - Airborne GPS and IMU data was immediately processed using the airport GPS base station data, which was available to the flight crew upon landing the plane. This ensured the integrity of all the mission data. These results were also used to perform the initial LiDAR system calibration test. 2) Raw LiDAR Data Processing - Technicians processed the raw data to LAS format flight lines with full resolution output before performing QC. A starting configuration file was used in this process, which contains the latest calibration parameters for the sensor. The technician also generated flight line trajectories for each of the flight lines during this process. 3) Verification of Coverage and Data Quality - Technicians checked flight line trajectory files to ensure completeness of acquisition for project flight lines, calibration lines, and cross flight lines. The intensity images were generated for the entire lift at the required post spacing for the project. The technician visually checked the intensity images against the project boundary to ensure full coverage. The intensity histogram was analyzed to ensure the quality of the intensity values. The technician also thoroughly reviewed the data for any gaps in project area. The technician generated a few sample TIN surfaces to ensure no anomalies were present in the data. Turbulence was inspected for and if it affected the quality of the data, the flight line was rejected and reflown. The technician also evaluated the achieved post spacing against project specified post spacing.
Raw LiDAR Data
20120202
Verified LiDAR Data
Fugro EarthData, Inc.
Rich McClellan
Project Manager
mailing and physical address
7320 Executive Way
Frederick
MD
21704
USA
301.948.8550
301.963.2064
rmcclellan@fugro.com
Mon-Fri 8:30am to 5:00pm
The boresight for each lift was done individually as the solution may change slightly from lift to lift. The following steps describe the Raw Data Processing and Boresight process: 1) Technician processed the raw data to LAS format flight lines using the final GPS/IMU solution. This LAS data set was used as source data for boresight. 2) Technician first used commercial software to calculate initial boresight adjustment angles based on sample areas selected in the lift- mini project. These areas cover calibration flight lines collected in the lift, cross tie and production flight lines. These areas are well distributed in the lift coverage and cover multiple terrain types that are necessary for boresight angle calculation. The technician then analyzed the result and made any necessary additional adjustment until it is acceptable for the mini project. 3) Once the boresight angle calculation was done for the mini project, the adjusted settings were applied to all of the flight lines of the lift and checked for consistency. The technician utilized commercial and proprietary software packages to analyze the matching between flight line overlaps for the entire lift and adjusted as necessary until the results met the project specifications. 4) Once the boresight adjustment was completed for each lift individually, the technician ran a routine to check the vertical misalignment of all flight lines in the project and also compared data to ground truth. The entire dataset was then adjusted to ground control points. 5) The technician ran a final vertical accuracy check between the adjusted data and surveyed ground control points after the z correction. The result was analyzed against the project specified accuracy to make sure it meets the project requirements
Verified LiDAR Data
20120305
Boresighted Data
Fugro EarthData, Inc.
Rich McClellan
Project Manager
mailing and physical address
7320 Executive Way
Frederick
MD
21704
USA
301.948.8550
301.963.2064
rmcclellan@fugro.com
Mon-Fri 8:30am to 5:00pm
Once boresighting is complete for the project, the project was set up for classification. The LiDAR data was cut to production tiles. The flight line overlap points, Noise points and Ground points were classified automatically in this process. Fugro EarthData, Inc. has developed a unique method for processing LiDAR data to identify and re-classify elevation points falling on vegetation, building, and other above ground structures into separate data layers. The steps are as follows: 1) Fugro EarthData, Inc. utilized commercial software as well as proprietary software for automatic filtering. The parameters used in the process were customized for each terrain type to obtain optimum results. 2) The Automated Process typically re-classifies 90-98% of points falling on vegetation depending on terrain type. Once the automated filtering was completed, the files were run through a visual inspection to ensure that the filtering was not too aggressive or not aggressive enough. In cases where the filtering was too aggressive and important terrain features were filtered out, the data was either run through a different filter or was corrected during the manual filtering process. 3) Interactive editing was completed in 3D visualization software which also provides manual and automatic point classification tools. Fugro EarthData, Inc. used commercial and proprietary software for this process. Vegetation and artifacts remaining after automatic data post-processing were reclassified manually through interactive editing. The hard edges of ground features that were automatically filtered out during the automatic filtering process were brought back into ground class during manual editing. Auto-filtering routines were utilized as much as possible within fenced areas during interactive editing for efficiency. The technician reviewed the LiDAR points with color shaded TINs for anomalies in ground class during interactive filtering. 4) All LAS tiles went through peer review after the first round of interactive editing was finished. This helps to catch misclassification that may have been missed by the interactive editing. 5) Upon the completion of peer review and finalization of bare earth filtering, the classified LiDAR point cloud work tiles went through a water classification routine based on the collected water polygons. 6) The time stamps for all points were converted to Adjusted Standard GPS time using proprietary software developed by Fugro EarthData, Inc. The data collection date and the current GPS time stamp were used in calculating the Adjusted Standard GPS time. 7) The classified point cloud data were packaged into UTM Zone 18 North Coordinates, NAD83(2007) in meters and the North American Vertical Datum of 1988 (NAVD88) in Meters using GEIOD09 for delivery. The data was also cut to the approved tile layout and clipped to the approved project boundary. The technician checked the output LAS files for coverage and format; d) the technician then QC’d the dataset for quality assurance and enhanced the Bare Earth classification in the project area for consistent data quality; ie) these final LiDAR tiles were then used in the hydro flattening process. 8) The classified LiDAR point cloud data were delivered in LAS 1.2 format: 1 – unclassified, 2 – ground, 7 – low points, 8 – model keypoints, water, 9 – water, and 12 – overlap points.
Boresighted Data
20130110
Classified LiDAR Point Cloud Data
Fugro EarthData, Inc.
Rich McClellan
Project Manager
mailing and physical address
7320 Executive Way
Frederick
MD
21704
USA
301.948.8550
301.963.2064
rmcclellan@fugro.com
Mon-Fri 8:30am to 5:00pm
0
Point
Point
Universal Transverse Mercator
18
0.999600
-75.000000
+00.000000
500000.000000
0.000000
coordinate pair
1
1
Meters
North American Datum of 1983 (National Spatial Reference System 2007)
Geodetic Reference System 80
6378137.000000
298.257222
North American Vertical Datum of 1988
1
Meters
Explicit elevation coordinate included with horizontal coordinates
Leica ALS60 MPiA sensor; 0.7m nominal post spacing
see process steps within this record
New York USDA NRCS
mailing and physical address
441 S. Salina St., Suite 354
Syracuse
New York
13202
USA
315.477.6525
cathy.crotty@ny.usda.gov
9:00am - 5:00pm
Downloadable Data
Any conclusions drawn from the analysis of this information are not the responsibility of the New York USDA NRCS or its partners.
20130125
20130125
New York USDA NRCS
mailing and physical address
441 S. Salina St., Suite 354
Syracuse
New York
13202
USA
315.477.6525
cathy.crotty@ny.usda.gov
9:00am - 5:00pm
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
None
None