2017 OLC FEMA Lidar: Grass Valley, OR

Geographic Extent: OLC Grass Valley FEMA Buffered Project Area, covering approximately 95,543 acres.

Dataset Description: The OLC Grass Valley FEMA LiDAR project called for the Planning, Acquisition, processing and derivative products of LIDAR data to be collected at a nominal pulse spacing (NPS) of 0.35 m. Project specifications are based on the U.S. Geological Survey National Geospatial Program LIDAR Base Specification, Version 1.2. The data were developed based on the Universal Transverse Mercator (UTM) 10N projection; horizontal datum of NAD83 (2011), meters; and vertical datum of NAVD88 Geoid 12A, meters. LiDAR data were delivered in RAW flight line swath format, processed to create Classified LAS 1.4 Files formatted to a 750 meter by 750 meter tiling scheme; Hydro-flattened Bare Earth DEMs tiled to the same 750 meter by 750 meter tiling scheme; and Bridge and Hydro-Flattening Breaklines in ESRI File-Geodatabase format.

Ground Conditions: LiDAR was collected in 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, Quantum Spatial established a total of 295 control points that were used to calibrate the LIDAR to known ground locations established throughout the OLC Grass Valley FEMA project area.

In addition to these lidar point data, the bare earth Digital Elevation Models (DEM) created from the lidar point data and the breakline data are also available. These data are available for download at the links provided in the URL section of this metadata record.

Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Breaklines and Raster DEM.

These raw lidar point cloud data were used to create classified lidar LAS files, 3D breaklines, and hydro-flattened DEMs as necessary.

CONTRACTOR: Quantum Spatial, Inc.

Ground Control Points were acquired and calibrated by Quantum Spatial, Inc.

All Lidar data acquisition, calibration, and follow-on processing were completed by the prime contractor.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey National Geospatial Program LIDAR Base Specification, Version 1.2",

"ldrsens" : "Leica ALS80",

"ldrmaxnr" : "unlimited",

"ldrnps" : "0.35 m",

"ldrdens" : "8 PPSM",

"ldranps" : "0.35 m",

"ldradens" : "8 PPSM",

"ldrfltht" : "1500 m",

"ldrfltsp" : "140 kts",

"ldrscana" : "30 degrees",

"ldrscanr" : "58.4 Hz",

"ldrpulsr" : "369.2 kHz",

"ldrpulsd" : "3 ns",

"ldrpulsw" : "0.25 m",

"ldrwavel" : "1064 nm",

"ldrmpia" : "1",

"ldrbmdiv" : "0.25 mrad",

"ldrswatw" : "804 m",

"ldrswato" : "60%",

"ldrcrs" : "North American Datum of 1983 (2011), UTM 10N, meters",

"ldrgeoid" : "NAVD88 Geoid 12A"

},

"ldraccur" : {

"ldrchacc" : "0.5 m",

"rawnva" : "0.076 m",

"rawnvan" : "43"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "PF 6",

"laswheld" : "Withheld points are identified as aerial distubrance, low ground noise and atmospheric distrubances.",

"lasolap" : "Swath overage points are described as one degree to either side of overlapping swath boundaries.",

"lasintr" : "12 bits",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare earth ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground Near Breakline"

},

"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 Quantum Spatial, Inc, USGS, the Oregon Lidar Consoritum (OLC), DOGAMI, 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.

LiDAR Mapping Suite 2.4, Applanix PosPac 7.1, Microstation Version 8.0, TerraScan Version 16, TerraModeler Version 16, TerraMatch Version 16, ESRI ArcGIS 10.3.1, Windows 7 Operating System

LAS data from the OLC Grass Valley FEMA project was compared to independent check points to determine the NVA of the LAS Swath and of the Bare Earth DEM.

Raw Swath Non-Vegetated Vertical Accuracy (NVA) Tested 0.076 meters non vegetated vertical accuracy at a 95 percent confidence level, derived according to NSSDA, in open terrain using (RMSEz) x 1.96000 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported against 43 NVA points using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the TIN. Swath points flagged as withheld were not included in the accuracy test. RMSE is 3.9 cm.

BareEarth DEM Non-Vegetated Vertical Accuracy (NVA) Tested 0.085 meters Non-vegetated vertical accuracy at a 95 percent confidence level, derived according to NSSDA, in open terrain using (RMSEz) x 1.96000 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported against 43 NVA points using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM.

Vegetated Vertical Accuracy (VVA): The required accuracy of the VVA at the 95th percentile according to specification is 0.294 meters. The VVA tested 0.107 meters at the 95th percentile using National Digital Elevation Program (NDEP)/ASPRS Guidelines against the DEM using 21 VVA points. No VVA errors larger than 95th percentile existed.

Data sets contain complete coverage of tiles. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness.

There are no void areas or missing data. The raw point cloud is of good quality and data passes Nonvegetated Vertical Accuracy specifications.

Classified LAS files were tested by Quantum Spatial for both vertical and horizontal accuracy. All data is seamless from one tile to the next, no gaps or no data areas.

Data is backed up to tape and to cloud storage.