2015 FEMA Lidar: Michigan - Part 3

The State of Michigan (DTMB) contracted with Sanborn to provide LiDAR mapping services for 6 counties in the State of Michigan. These counties include Cass, Genesee, Kalamazoo, Lapeer, Shiawassee, and St, Joseph. This metadata record describes the three counties of Genessee, Lapeer, and Shiawassee and 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.

Utilizing multi-return systems, Light Detection and Ranging (LiDAR) data in the form of 3-dimensional positions of a dense set of mass points was collected for the 6 counties in November of 2015. All systems consist of geodetic GPS positioning, orientation derived from high-end inertial sensors and highly-accurate lasers. The sensor is mounted inside an aircraft and emits rapid pulses of light, through an opening in the fuselage, that are used to determine distances between the plane and terrain below.

LAS data products are suitable for 1 foot contour generation. USGS LiDAR Base Specification 1.2, QL2. 19.6 cm NVA.

Genessee County: data covers approximately 650 square miles

Lapeer County: data covers approximately 663 square miles

Shiawassee County: data covers approximately 541 square miles

The purpose of this data set is the acquisition and production of high resolution elevation data for the State of Michigan. This LiDAR operation was designed to create high resolution data sets that will establish an authoritative source for elevation information for the State of Michigan to create detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments, and hydrologic modeling.

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 (Geoid12a) for converting ellipsoidal heights to orthometric heights. Units - intl feet

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "QL2 meeting USGS 1.2 specifications",

"ldrsens" : "Leica ALS70",

"ldrmaxnr" : "4",

"ldrnps" : "0.65",

"ldrdens" : "1.67",

"ldradens" : "2.2",

"ldranps" : "0.71",

"ldrfltht" : "2250",

"ldrfltsp" : "135",

"ldrscana" : "32",

"ldrscanr" : "64",

"ldrpulsr" : "167",

"ldrpulsd" : "10",

"ldrpulsw" : "3",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.3",

"ldrswatw" : "1222",

"ldrswato" : "30",

"ldrcrs" : "NAD_1983_2011_State_Plane_Michigan_South_2113_Ft_Intl",

"ldrgeoid" : "NGS Geoid12a"

},

"ldraccur" : {

"ldrchacc" : "19.6",

"rawnva" : "0.082",

"rawnvan" : "79",

"clsnva" : "0.079",

"clsnvan" : "79",

"clsvva" : "0.229",

"clsvvan" : "70"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld points were identified using the standard LAS withheld bit.",

"lasolap" : "Swath "overage" points were identified using the standard LAS overlap bit.",

"lasintr" : "10",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare-earth"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "All noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

QL2 meeting USGS 1.2 specifications

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 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 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 FVA, SVA, and CVA were computed. The vertical accuracy was tested with independent survey check points located in various terrain types within the project 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 FVA be 9.25 cm (18.13 cm or better @ 95 percent confidence level).

The NVA was tested using 79 independent survey check points located in flat terrain types within Genesee, Lapeer, and Shiawassee Counties. The survey checkpoints were distributed throughout the block area. The 79 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 RMSE was computed to be 0.042 m. AccuracyZ has been tested to meet 10 cm Non Vegetated 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)/ASRPS Guidelines.

The VVA was tested using 70 independent survey check points located in vegetated terrain types within Genesee, Lapeer, and Shiawassee Counties. The survey checkpoints were distributed throughout the block area. The 155 independent check points contained all FVA and SVA class 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 RMSE was computed to be 0.113 m, or 0.229 m @ 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 Fundamental Vertical Accuracy, Supplemental Vertical Accuracy, and Consolidated Vertical Accuracy specifications.

LiDAR data is collected within the project area and processed. After the DEMs were created, the dataset was verified against control. Control was collected for 3 adjoining counties. Results are shown for Genesee, Lapeer, and Shiawassee Counties.

Data is backed up to tape and to cloud storage.

The 2015 FEMA Michigan Part 3 lidar was ingested into the Data Access Viewer for custom product generation by leveraging USGS hosted Entwine Point Tiles.