2017 Lidar: Wayne County, MI

This metadata record describes the Classified Point Cloud (LAS) for the 2017 Michigan LiDAR project covering approximately 612 square miles, covering Wayne County.

The NOAA Office for Coastal Management (OCM) downloaded this data set from this USGS site:

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_MI_WayneCo_2017_LAS_2018/

These files were processed to the Data Access Viewer (DAV) and https. The total number of files downloaded and processed was 2901.

Hydro breaklines are also available. These data are available for download at the link provided in the URL section of this metadata record. Please note that this product has not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments, and hydrologic modeling. LAS data products are suitable for 1 foot contour generation. USGS LiDAR Base Specification 1.2, QL2. 19.6 cm NVA.

Project Projection, Datums and Units. Projection - State Plane Michigan South. Horizontal datum - North American Datum of 1983 (NAD83 (2011)). Vertical datum - North American Vertical Datum of 1988 (NAVD88) using the latest geoid (Geoid12B) for converting ellipsoidal heights to orthometric heights. Units - intl feet

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS Base Specification 1.2, QL2 meeting 19.6cm NVA",

"ldrsens" : "Leica ALS70",

"ldrmaxnr" : "4",

"ldrnps" : "0.67",

"ldrdens" : "2.2",

"ldranps" : "0.67",

"ldradens" : "2.2",

"ldrfltht" : "2345",

"ldrfltsp" : "130",

"ldrscana" : "38",

"ldrscanr" : "47.3",

"ldrpulsr" : "235",

"ldrpulsd" : "10",

"ldrpulsw" : "0.53",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.3",

"ldrswatw" : "1615",

"ldrswato" : "30",

"ldrcrs" : "NAD_1983_2011_StatePlane_Michigan_South_FIPS_2113_Ft_Intl",

"ldrgeoid" : "NGS Geoid12B"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0.13",

"rawnvan" : "185",

"clsnva" : "0.13",

"clsnvan" : "185",

"clsvva" : "0.20",

"clsvvan" : "132"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld points were identified in these files with the withheld flag",

"lasolap" : "Overlap points were identified in these files with the overlap flag",

"lasintr" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare earth"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground (Breakline Proximity)"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridges"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

USGS Base Specification 1.2, QL2 meeting 19.6 cm NVA

The State of Michigan Geographic Information Systems digital data have been tested and their documentation carefully reviewed. However, the State of Michigan and its representatives make no warranty or representation, either expressed or implied, with respect to the digital data and their documentation, their quality, performance, merchantability, or fitness for a particular purpose. The digital data are distributed on "as is" basis, and the user assumes all risk to their quality, the results obtained from their use, and the performance of the data. In no event will the State of Michigan or its representatives be liable for any direct, indirect, special, incidental or consequential damages resulting from and defect in the State of Michigan or in their documentation. This disclaimer of warranty is exclusive and in lieu of all others, oral or written, express or implied. No agent or employee is authorized to make any modification, extension, or addition to this warranty.

Any conclusions drawn from the analysis of this information are not the responsibility of the State of Michigan, USGS, 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.

Microsoft Windows 7; ESRI ArcCatalog 9.3.1.1850

Horizontal positional accuracy for Wayne is dependent upon the quality of the GPS/INS solution, sensor calibration and ground conditions at the time of data capture. The standard system results for horizontal accuracy meet or exceed the project specified 1.0 meter RMSE. This value is computed by comparing ground control to a DEM derived from the classified LiDAR data and represents the RMSE of residuals on controls within the project area.

For the DEM data derived from the classified point cloud, the NVA and VVA were computed. The vertical accuracy was tested with independent survey check points located in various terrain types within the 12 county control area. These check points were not used in the calibration or post processing of the lidar point cloud data. The survey check points were distributed throughout the block area. Specifications for this project require that the NVA be 19.6 cm or better @ 95 percent confidence level.

The raw NVA was tested using 185 independent survey check points located in flat terrain types within the 12 county area. The survey checkpoints were distributed throughout the block area. The 185 independent check points were surveyed using static GPS base stations collecting point location for 20 minute intervals. Elevations were measured for the x,y,z location of each check point. Elevations interpolated from the surface were then compared to the elevation values of the surveyed control. The RMSEz was computed to be 0.066m. AccuracyZ has been tested to meet 10 cm Nonvegetated Vertical Accuracy at 95 Percent 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)/ASPRS Guidelines.

The NVA was tested using 185 independent survey check points located in bare earth terrain types within the 12 county area. The 185 independent check points contained all NVA points and were surveyed using static GPS base stations collecting point location for 20 minute intervals. Elevations were measured for the x,y,z location of each check point. Elevations interpolated from the DEM surface were then compared to the elevation values of the surveyed control. The RMSEz was computed to be 0.066m, or 0.13m @ 95 percent confidence level defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.

The VVA was tested using 132 independent survey check points located in various vegetation terrain types within the 12 county area. The 132 independent check points were surveyed using static GPS base stations collecting point location for 20 minute intervals. Elevations were measured for the x,y,z location of each check point. Elevations interpolated from the DEM surface were then compared to the elevation values of the surveyed control. The RMSEz was computed to be 0.104m, or 0.20m @ 95th Percentile defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.

LiDAR data is collected for the project area. Post processing of the simultaneously acquired GPS/INS is performed and applied to the laser returns to output a point cloud in the specified project coordinate system and datums. The point cloud data is then subjected to automated classification routines to assign all points in the point cloud to ground, water, overlap and unclassified point classes. Anomalous laser returns that occur infrequently are removed entirely from the data set. Once clean bare earth points are established, DEMs are created using bare earth points and hydro features. The DEM surface is then compared to the survey checkpoints. These accuracies must pass the Non-Vegetated and Vegetated Vertical Accuracy specifications.

LiDAR data is collected within the project area and processed. After all of the deliverables were created, the dataset was verified against control. The control points were compared to the following counties and reported as one accuracy assessment: Tuscola, Huron, Sanilac, St. Clair, Macomb, Oakland, Jackson, Washtenaw, Wayne, Hillsdale, Lenawee, Monroe.

Data is backed up to tape and to cloud storage.