2019 USGS Lidar: City of Champaign, IL

Product: These lidar data are processed Classified LAS 1.4 files, formatted to 301 individual 1000 meter x 1000 meter tiles; used to create intensity images, 3D breaklines and hydro-flattened DEMs as necessary.

Geographic Extent: Champaign City Illinois, covering approximately 116 square miles. Cities included are Champaign and Urbana, Illinois. A lidar survey was collected over one (1) area of interest (AOI) in Illinois identified as the Option 1 AOI.

Dataset Description: Champaign City Illinois 2019 Lidar project called for the planning, acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.354 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.3; Quality Level 1. The data was developed based on a horizontal projection/datum of NAD83 (2011), Albers Equal Area, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 301 individual 1000 x 1000 meter tiles, as 301 tiled Intensity Imagery, and as 301 tiled bare earth DEMs; all tiled to the same 1000 x 1000 meter schema. The vegetation classes are: Low vegetation = 0.5-5 feet, Medium vegetation = 5-20 feet, High vegetation >20 feet. Vegetation classes may also include buildings or parts of buildings that automated filters did not detect.

Ground Conditions: Lidar was collected on April 16, 2019, 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, Surveying and Mapping, LLC (SAM) established a total of 9 ground control points, 8 of which were located inside the Option 1 AOI and were used to calibrate the lidar to known ground locations established throughout the project area. An additional 13 independent accuracy checkpoints, 13 in Bare Earth and Urban landcovers (13 NVA points), 8 in tall Grass/tall weeds/crops, Brush lands/short trees, Forested categories (8 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the Entwine Point Tiles (EPT) hosted by USGS on Amazon Web Services.

To acquire QL1+ lidar detailing surface elevation data, vegetation, and buildings for use to support the 3DEP mission, the Natural Resources Consevation Services (NRCS), Federal Emergency Management (FEMA) Risk Mapping, Assessment, and Planning (MAP) program, and Illinois State Geological Survey's Height Modenization Program. 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 this lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 0.5 meter cell size. These lidar point cloud data were used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

USGS Contract No. G17PC00007 CONTRACTOR: Aerial Services, Inc. Lidar data were acquired and calibrated by the prime contractor. PRIME: Aerial Services, Inc. manually edited bare earth surface and building rooftop cleanup, preformed hydro collection, flattening, produced bare earth DEMs for the Option 1 AOI. All follow-on processing was completed by the prime contractor.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Lidar Specification v1.3",

"ldrsens" : "Leica ALS70-HP",

"ldrmaxnr" : "4",

"ldrnps" : "0.354",

"ldrdens" : "8",

"ldranps" : "0.354",

"ldradens" : "8",

"ldrfltht" : "1100",

"ldrfltsp" : "150",

"ldrscana" : "60",

"ldrscanr" : "60",

"ldrpulsr" : "246",

"ldrpulsd" : "4",

"ldrpulsw" : "1.22",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.24",

"ldrswatw" : "589",

"ldrswato" : "30",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12B"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0",

"rawnvan" : "0",

"clsnva" : "0",

"clsnvan" : "0",

"clsvva" : "0",

"clsvvan" : "0"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

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

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

},

"lasclass" : {

"clascode" : "20",

"clasitem" : "Ignored Ground"

}

}}

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 and 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. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.

This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class.

USGS Determined Vertical Accuracy:

Non-Vegetated Vertical Accuracy (NVA) = 5 cm RMSE

Vegetated Vertical Accuracy (VVA) = 12.08 cm at 95th Percentile

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.

Data covers the entire area specified for this project.

Data is backed up to tape and to cloud storage.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS Entwine Point Tile (EPT) file hosted on Amazon Web Services (AWS) into the Digital Coast Data Access Viewer (DAV). The DAV accesses the point cloud as it resides on AWS under the usgs-lidar-public-container.