Quantum Spatial, Inc.
20171215
Arkansas 2016 QL2 LiDAR; Swath Point Cloud; Lift: 20161218-A2_C-FVZM_SN7229
Lidar point cloud
Product: These lidar data are unclassified swath LAS 1.4 files, used to create classified LAS 1.4 files and subsequent data.
Geographic Extent: Twenty counties in northern Arkansas and southeastern Oklahoma, covering approximately 11,421 total square miles.
Dataset Description: Arkansas 2016 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 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data for counties in the eastern AOIs were developed based on a horizontal projection/datum of NAD83 (2011), UTM Zone 15, meters and vertical datum of NAVD88 (GEOID12B), metes. Lidar data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS 1.4 files formatted to 13,708 individual 1,500-meter x 1,500-meter tiles, as tiled intensity imagery, and as tiled bare earth DEMs; all tiled to the same 1,500-meter x 1,500-meter schema. Continuous breaklines were produced in Esri file geodatabase format. Building footprints were created in Esri file geodatabase format.
Ground Conditions: Lidar was collected in winter/spring of 2016/2017, 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, Quantum Spatial, Inc. established a total of 225 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 379 independent accuracy checkpoints, 219 in Bare Earth and Urban landcovers (219 NVA points), 160 in Forested, Brushland/Trees, and Tall Weeds/Crops categories (160 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 intensity images, breaklines and raster DEMs. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened digital elevation models (DEMs) with a 1-meter cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.
USGS Contract No. G10PC00016 Task Order No. G17PD00010. CONTRACTOR: Quantum Spatial, Inc. SUBCONTRACTOR: Keystone Aerial Surveys, Inc., Airborne Imaging, Inc., and Atlis Geomatics, Inc. Lidar data were acquired by Keystone Aerial Surveys, Inc. Airborne Imaging, Inc., and Atlis Geomatics, Inc. All follow-on processing was completed by the prime contractor.
USGS-NGP Base Specification v1.2
Leica ALS 70
Unlimited
0.7
2.04
0.7
2.04
1900
160
40
53
284
4
0.22
1064
1
0.22
1200
30
GEOID12B
NAD 1983 (2011) UTM Zone 15 meters
0
0.089
216
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
0
Never processed
20161218
ground condition
None planned
-93.4425332051
-93.1952113918
36.5068679504
35.8200201102
None
Model
LAS Point Cloud
Remote Sensing
Elevation Data
Lidar
Hydrology
None
Arkansas
Baxter County
Boone County
Carroll County
Cleburne County
Fulton County
Independence County
Izard County
Johnson County
Lawrence County
Madison County
Marion County
Newton County
Searcy County
Sharp County
Stone County
Van Buren County
Oklahoma
Adair County
Le Flore County
McCurtain County
Sequoya County
No restrictions apply to this 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 its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.
Data covers the entire area specified for this project.
These raw 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.
The project specifications require that only Non-Vegetated Vertical Accuracy (NVA) be computed for raw lidar point cloud swath files. The required accuracy (ACCz) is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in the "bare earth" and "urban" land cover classes. The NVA was tested with 216 checkpoints located in bare earth and urban (non-vegetated) areas. These check points were not used in the calibration or post processing of the lidar point cloud data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the unclassified lidar surface were measured for the x,y location of each check point. Elevations interpolated from the lidar surface were then compared to the elevation values of the surveyed control points. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.
0.089
Tested 0.089 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the raw lidar point cloud swath files was calculated against TINs derived from the final calibrated and controlled swath data using 216 independent checkpoints located in Bare Earth and Urban land cover classes.
Raw Data and Boresight Processing: 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) Technicians 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) Technicians first used Quantum Spatial, Inc. proprietary and commercial software to calculate initial boresight adjustment angles based on sample areas selected in the lift. 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 results and made any necessary additional adjustment until it is acceptable for the selected areas. 3) Once the boresight angle calculation was completed for the selected areas, the adjusted settings were applied to all of the flight lines of the lift and checked for consistency. The technicians utilized commercial and proprietary software packages to analyze how well flight line overlaps match for the entire lift and adjusted as necessary until the results met the project specifications. 4) Once all lifts were completed with individual boresight adjustment, the technicians checked and corrected the vertical misalignment of all flight lines and also the matching between data and ground truth. The relative accuracy was less than or equal to 7 cm RMSEz within individual swaths and less than or equal to 10 cm RMSEz or within swath overlap (between adjacent swaths). 5) The technicians ran a final vertical accuracy check of the boresighted flight lines against the surveyed check points after the z correction to ensure the requirement of NVA = 19.6 cm 95% Confidence Level (Required Accuracy) was met.
2017
Point
Universal Transverse Mercator
15
0.9996
-93.0
0.0
500000.0
0.0
coordinate pair
0.01
0.01
meters
North American Datum of 1983 (2011)
Geodetic Reference System 80
6378137.0
298.257222101
North American Vertical Datum of 1988 (GEOID12B)
0.01
meters
Explicit elevation coordinate included with horizontal coordinates
20171215
Quantum Spatial
mailing and physical
523 Wellington Way
Lexington
KY
40503
USA
859-277-8700
859-277-8901
Monday through Friday 8:00 AM to 5:00 PM (Eastern Time)
If unable to reach the contact by telephone, please send an email. You should get a response within 24 hours.
FGDC Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998
None.
None.
None.
Unclassified
NONE