2018 USGS Lidar: Ottawa NF, MI

Product: This lidar data set includes classified LAS 1.4 files, with unclassified (1), ground (2), low vegetation (3), medium vegetation (4), high vegetation (5), building (6), noise (7), water (9), ignored ground (10), withheld (11), and bridge (17).

Geographic Extent: Four counties in Michigan, covering approximately 2,563 total square miles.

Dataset Description: The Ottawa National Forest, MI, 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 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.2. The data were developed based on a horizontal projection/datum of NAD83 (2011), State Plane Michigan North FIPS 2111, Intl feet and vertical datum of NAVD88 (GEOID12B), Intl feet. LiDAR data were delivered as processed Classified LAS 1.4 files formatted to 11,799 individual 2,500 feet x 2,500 feet tiles, as tiled intensity imagery, and as tiled bare earth DEMs; all tiled to the same 2,500 feet x 2,500 feet schema. Continuous breaklines were produced in Esri file geodatabase format.

Ground Conditions: LiDAR was collected in spring of 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, Quantum Spatial, Inc. utilized a total of 59 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 143 independent accuracy checkpoints, 81 in Bare Earth and Urban landcovers (81 NVA points), 62 in Tall Weeds categories (62 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

Tiled and mosaicked hydro-flattened bare-earth DEMs, continuous breaklines, and tiled and mosaicked intensity imagery are available from USGS National Map.

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 2.5-foot 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. G16PC00016, Task Order No. 140G0218F00167; CONTRACTOR: Quantum Spatial, Inc.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Specification v1.2",

"ldrsens" : "Leica ALS70",

"ldrmaxnr" : "4",

"ldrnps" : "0.6",

"ldrdens" : "2.8",

"ldranps" : "0.6",

"ldradens" : "2.8",

"ldrfltht" : "2000",

"ldrfltsp" : "150",

"ldrscana" : "18",

"ldrscanr" : "56",

"ldrpulsr" : "278",

"ldrpulsd" : "4",

"ldrpulsw" : "0.44",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1300",

"ldrswato" : "26",

"ldrgeoid" : "GEOID12B",

"ldrcrs" : "NAD83 (2011) State Plane Michigan North FIPS 2111, Intl feet"

},

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Specification v1.2",

"ldrsens" : "Leica ALS80",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.62",

"ldrdens" : "2.63",

"ldranps" : "0.62",

"ldradens" : "2.63",

"ldrfltht" : "1900",

"ldrfltsp" : "160",

"ldrscana" : "19",

"ldrscanr" : "53.3",

"ldrpulsr" : "282.8",

"ldrpulsd" : "4",

"ldrpulsw" : "0.42",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1308",

"ldrswato" : "35",

"ldrgeoid" : "GEOID12B",

"ldrcrs" : "NAD83 (2011) State Plane Michigan North FIPS 2111, Intl feet"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0.849",

"rawnvan" : "81"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld (ignore) points were identified in these files using the standard LAS Withheld bit",

"lasolap" : "Swath "overage" points were identified in these files using the standard LAS overlap bit",

"lasintr" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare-Earth Ground"

},

"lasclass" : {

"clascode" : "3",

"clasitem" : "Low Vegetation"

},

"lasclass" : {

"clascode" : "4",

"clasitem" : "Medium Vegetation"

},

"lasclass" : {

"clascode" : "5",

"clasitem" : "High Vegetation"

},

"lasclass" : {

"clascode" : "6",

"clasitem" : "Buildings"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "11",

"clasitem" : "Withheld/Reserved Points"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

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 or 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.

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 81 checkpoints located in bare earth and urban (non-vegetated) areas. These checkpoints 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 checkpoint. 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.

The project specifications require the accuracy (ACCz) of the derived DEM be calculated and reported in two ways: 1. The required NVA 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. This is a required accuracy. The NVA was tested with 81 checkpoints located in bare earth and urban (non-vegetated) areas. 2. Vegetated Vertical Accuracy (VVA): VVA shall be reported for "tall weeds" land cover classes. The target VVA is: 29.4 cm at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for LiDAR Data, i.e., based on the 95th percentile error in all vegetated land cover classes combined. This is a target accuracy. The VVA was tested with 62 checkpoints located in forested and tall weeds (vegetated) areas. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. 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.

Tested 0.849 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 81 independent checkpoints located in Bare Earth and Urban land cover classes.

Tested 0.845 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 DEM was calculated using 81 independent checkpoints located in the Bare Earth and Urban land cover categories.

Tested 1.37 meters VVA was calculated using 62 checkpoints located in the Forested and Tall Weeds land cover categories at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for LiDAR Data. Tested against the DEM.

All files are inspected to ensure that they conform to the specified file naming conventions, all files load in their correct geographic position, all files conform to the project specifications for file standard and content.

Data cover the entire area specified for this project.

Data is backed up to tape and to cloud storage.