|Originator||AeroMetric, Inc. and Minnesota Department of Natural Resources|
|Title||LiDAR Elevation, Blue Earth County, Minnesota, 2012|
|Abstract||The project vendor, AeroMetric, Inc., acquired highly accurate Light Detection and Ranging (LiDAR) elevation data for Blue Earth County in south central Minnesota in Spring 2011. The project area consists of approximately 2,260 square kilometers (862 square miles). LiDAR data are in the UTM Zone 15 coordinate system, NAD83 NAVD88 Geoid09 meters. The tiling scheme is 16th USGS 1:24,000 quadrangle tiles.
The vendor delivered the data to the Minnesota Department of Natural Resources (DNR) in several formats:
1) One-meter digital elevation model
2) Edge-of-water breaklines
3) Classified LAS formatted point cloud data
DNR staff created two additional products: two-foot contours and building outlines.
Note: This metadata record was created at the Minnesota Geospatial Information Office by combining information supplied by AeroMetric and DNR.
|Purpose||The Minnesota Elevation Mapping Project was initiated to support the development of high accuracy land surface information for the purposes of improving water quality, flood emergency preparedness and response, floodplain mapping, transportation planning and design, recreational planning and design, urban planning and to provide more efficient and effective project planning and execution. This project was funded by the Clean Water Fund of the Clean Water, Land and Legacy Amendment.
The project consisted of acquisition, post-processing, and classification of LiDAR data and creation of products derived from the acquired data.
|Time Period of Content Date||04/06/2012|
|Currentness Reference||Date LiDAR data was collected.|
|Maintenance and Update Frequency||Unknown|
|Spatial Extent of Data||Blue Earth County in south central Minnesota|
|Place Keywords||Blue Earth County, Minnesota|
|Theme Keywords||elevation, LiDAR, DEM, digital elevation model, contour, topographic, topo, DTM, LAS, breakline|
|Theme Keyword Thesaurus||ISO 19115|
|Use Constraints||Users should be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions.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. Acknowledgment of the Minnesota Department of Natural Resources would be appropriate for products derived from these data.
See Disclaimer field for complete use conditions.
|Contact Person Information||Rob Merry,
4020 Technology Parkway
Sheboygan, WI 53083
|Browse Graphic||None available|
|Associated Data Sets||1. Blue Earth County LiDAR Elevation 2005: www.mngeo.state.mn.us/chouse/metadata/lidar_blueearth2005.html
2. For more information about elevation data for Minnesota, see: www.mngeo.state.mn.us/chouse/elevation/index.html
|Section 2||Data Quality|
|Attribute Accuracy||See Vertical Positional Accuracy field|
|Horizontal Positional Accuracy||Airborne data has been compared with ground survey check points to determine positional accuracy. The dataset was acquired in four missions covering approximately 2,260 square kilometers (862 square miles) from an altitude of 2400 meters above ground level (AGL) and has a horizontal accuracy of 0.44 meters (per manufacturers system specifications).|
|Vertical Positional Accuracy||The Fundamental Vertical Accuracy (FVA) of the Classified Bare Earth for the Blue Earth data set achieved 11.4 cm (at 95% confidence level) in the "Open Terrain" land cover category. 26 control points were used in this evaluation.
Vertical accuracy was to achieve a RMSE Z of 12.5 cm (95% confidence level of less than 24.5 cm) or better in the "Open Terrain" land cover category for all areas in accordance with NDEP and ASPRS methodologies. Accuracy statement is based on areas of moderate to flat terrain. Diminished accuracies are to be expected in areas in dense vegetation. The accuracy of the LiDAR data as tested met or exceeded the vertical accuracy requirements, however, derived products may be less accurate in areas of dense vegetation due to a lesser number of points defining the bare-earth in such areas.
Minnesota Dept. of Natural Resources staff tested the vertical accuracy and concluded: "While the consolidated RMSE for this project area exceeds project standards by a small degree the data was approved due to the fact that the most egregious errors are in the forested category. Based on comparisons with aerial photography it was noted that the points most in error are in heavily forested areas. The lack of pictures of ground cover for the validation points makes it difficult to impose contract limitations. USGS specifications state that the forestry category is negotiable. Based on the quality of the other categories it was deemed acceptable." The full report is online: ftp.lmic.state.mn.us/pub/data/elevation/lidar/county/blueearth/2012/blue_earth_county_validation_report.pdf
|Lineage||LiDAR data and derivative products produced in compliance with this task order are part of the data to be obtained under Contract number E112-10821 with Minnesota Department of Natural Resources. Specifications listed below are based on National Digital Elevation Program (NDEP) and the American Society for Photogrammetry and Remote Sensing (ASPRS) and Other High Quality Digital Topography.
AEROMETRIC, INC. PROCESSING INFORMATION:
This LiDAR data set consists of approximately 2,260 square kilometers (862 square miles). The airborne GPS and IMU data were processed immediately following each mission. In addition, a sample of the LIDAR data was post-processed at the completion of each mission and the data was reviewed to ensure planned data quality and coverage.
The LiDAR data was captured using a twin engine fixed wing aircraft equipped with a LiDAR system. The LiDAR system includes a differential GPS unit and inertial measurement system to provide highly accurate positioning.
1. Scanner - Leica ALS70
2. Flight Height - 2400 meters above ground level
3. Swath Width - 40 degrees
4. Sidelap - 30 percent
5. Nominal Point Spacing - 1.4 meters
GPS and IMU processing parameters:
1. Processing Programs and version - TerraTec TerraPOS, TPAS TC GNSS/INS Processor version 3.10, IPAS Pro version 2.01.02
2. IMU processing monitored for consistency and smoothness - Yes
Point Cloud Processing:
1. Program and version - ALS Post Processor version 2.74 build#9
2. Horizontal Datum - NAD83 HARN
3. Horizontal Coordinates - UTM zone 15N, in meters
4. Vertical Datum - NAVD88
5. Geoid Model used to reduce satellite derived elevations to orthometric heights - Geoid09 (Meters)
1. Processing Programs and versions - ALS Post Processor version 2.74 build#9, TerraSolid TerraScan (version 012.010), TerraModeler (version 012.005 and TerraMatch (version 012.004) and Intergraph MicroStation (version.08.05.02.70).
2. Point Cloud data was imported to TerraScan in a Microstation V8 (V) CAD environment on a specified tiling scheme based on the US National Grid Square.
3. Analyzed the data for overall completeness and consistency. This was to ensure that there were no voids in the data collection.
4. QC (Quality Control) for calibration errors in the dataset. This was accomplished by sampling the data collected across all flight lines and classifying the individual lines to ground. The software used the ground-classified lines to compute corrections (Heading, Pitch, Roll, and Scale).
5. Orientation corrections (i.e. Calibration corrections) were then applied (if needed) to the entire dataset.
6. Automatic ground classification was performed using algorithms with customized parameters to best fit the project area. Several areas of varying relief and planimetric features were inspected to verify the final ground surface.
7. AeroMetric, Inc. provided Quality Assurance and Quality Control (QAQC) data for this project. AeroMetric processed QA/QC points in 'open terrain' land cover category that were used to test the accuracy of the LiDAR ground surface. TerraScan's Output Control Report (OCR) tool was used to compare the QAQC data to the LIDAR data. This routine searches the LIDAR dataset by X and Y coordinate, finds the closest LIDAR point and compares the vertical (Z) values to the known data collected in the field. Based on the QAQC data, a bias adjustment was determined, and the results were applied to the LIDAR data. A final OCR was performed on the entire data set to assess any adjustment and ensure that data was accurately positioned.
8. Once the automatic processing and testing of LiDAR was complete, Aerometric meticulously reviewed the generated bare-earth surface data to insure that proper classification was achieved. Each tile was reviewed for accuracy and consistency of the macro ground classification. Also during this phase, MicroStation was used to generate linework representing water bodies and rivers. Separate linework was also placed in instances where overpasses had blocked enough valid ground returns or water gave too few ground returns to reasonably portray the ground surface. A proprietary in-house software program was then run to drape the river linework in a flowing fashion. Contours were generated on the river breaklines to review monotonicity of the draped linework.
9. After the LiDAR data was finalized for vertical placement, a macro was run via TerraScan to output a dataset generated on a per swath basis as part of the final deliverables. All points of the swath were reclassified to class 0 during this step.
10. Final deliverables were generated and output to a client-specified tiling scheme set of geodatabases.
1. After review of bare-earth surface data and breakline generation was completed, final DEMs were produced to a client-specified tiling scheme.
2. Using TerraModeler, DEMs were generated in an ASCII format on a per tile basis. These DEM were reviewed using GlobalMapper for adherence and completeness to the data and tile layout used during the creation process.
3. Following review acceptance, the ASCII files were processed into a FLOAT format. These files were converted using ArcMap to the delivered IMG format.
DNR PROCESSING INFORMATION
Additional products generated by Minnesota DNR staff are in the geodatabase for each of the tiles:
1. Two-foot contours were created by resampling the 1-meter DEM to 3 meters, then smoothing the 3-meter grid using a neighborhood average routine, and then creating contours from this surface using standard ArcGIS processing tools.
2. Building outlines were created by extracting from the LAS files those points with Classification 6 (buildings), then grouping those points within 3 meters of each other into a single cluster and then creating an outline around those points. This was done using standard ArcMap tools.
3. Hillshades were created from the one- and three-meter DEMs using standard ArcMap tools. Azimuth value = 215, Altitude = 45, Z-Factor = 1
|Section 3||Spatial Data Organization (not used in this metadata)|
|Section 4||Coordinate System|
|Horizontal Coordinate Scheme||Universal Transverse Mercator|
|UTM Zone Number||15|
|Publisher||Minnesota Department of Natural Resources|
|Contact Person Information||Nancy Rader,
GIS Data Coordinator|
Minnesota Geospatial Information Office
658 Cedar Street
St. Paul, MN 55155
|Distributor's Data Set Identifier||Blue Earth LiDAR 2012|
|Distribution Liability||1. MnGeo's data disclaimer is online: www.mngeo.state.mn.us/chouse/disclaimer.html
2. Minnesota Department of Natural Resources General Geographic Data License Agreement
1) The Minnesota Department of Natural Resources (MNDNR) grants to you a non-exclusive, non-sublicensable, license to use these digital data. This License agreement applies to all digital data acquired from DNR staff, FTP sites, or other internet-based delivery systems. In the event that another license agreement issued by DNR staff is explicitly associated with a particular data set, the terms of the other license agreement prevail, and the terms expressed in this more general license agreement are nullified.
2) The MNDNR makes no representations about the suitability of these data for any purpose. The data are provided 'as is' without express or implied warranties, including warranties of merchantability and fitness for a particular purpose or non-infringement.
3) MNDNR is not obligated to provide updates to these data in the event that newer versions become available. MNDNR provides documentation when available through established distribution mechanisms.
4) The user relieves the MNDNR and its respective officers, agents, and employees of any liability for any and all damages resulting from use of mis-use of these data including, but not limited to:
a. Incidental, consequential, special or indirect damages of any sort, whether arising in tort, contract or otherwise, even if MNDNR has been informed of the possibility of such damages, or
b. For any claim by any other party. Furthermore, in States that do not allow the exclusion of limitation of incidental or consequential damages, you may not use these data.
5) When these data are used in the development of digital or analog(hardcopy) products, MNDNR must be acknowledged as having contributed data to the development of the product.
6) Although the use of these data are not restricted, they may not be sold commercially or privately without the written permission of MNDNR.
|Ordering Instructions||The LiDAR data provided by DNR may be downloaded from MnGeo's FTP site by clicking on the link below.
For more help with Minnesota's LiDAR data, see www.mngeo.state.mn.us/chouse/elevation/lidar.html
|Online Linkage||I AGREE to the notice in "Distribution Liability" above. Clicking to agree will either begin the download process or link to download information. See "Ordering Instructions" above for details.|
|Section 7||Metadata Reference|
|Contact Person Information||Nancy Rader,
GIS Data Coordinator|
Minnesota Geospatial Information Office
658 Cedar Street
St. Paul, MN 55155
|Metadata Standard Name||Minnesota Geographic Metadata Guidelines|
|Metadata Standard Version||1.2|
|Metadata Standard Online Linkage||http://www.mngeo.state.mn.us/committee/standards/mgmg/metadata.htm|