LiDAR Elevation, Minnesota River Basin, Southwest Minnesota, 2010

This page last updated: 04/28/2014
Metadata created using Minnesota Geographic Metadata Guidelines


Go to Section:
1. Overview
2. Data Quality
3. Data Organization
4. Coordinate System
5. Attributes
6. Distribution - Get Data
7. Metadata Reference

Section 1 Overview
Originator AeroMetric, Inc.
Title LiDAR Elevation, Minnesota River Basin, Southwest Minnesota, 2010
Abstract AeroMetric (now Quantum Spatial) acquired highly accurate Light Detection and Ranging (LiDAR) elevation data for the Minnesota portion of the Minnesota River Basin. The project area of approximately 17,260 square miles covered the following 25 Minnesota counties: Brown, Chippewa, Cottonwood, Douglas, Faribault, Jackson, Kandiyohi, Lac qui Parle, Le Sueur, Lincoln, Lyon, Martin, Murray, Nicollet, Nobles, Pipestone, Pope, Redwood, Renville, Rock, Sibley, Swift, Waseca, Watonwan, and Yellow Medicine.

LiDAR data acquisition, control and QC surveys were completed during the spring and fall leaf-off periods: April 8 - May 5 and November 2 - 19, 2010. The tiling scheme is 16th USGS 1:24,000 quadrangle tiles. Aerometric delivered the data to the Minnesota Department of Natural Resources (DNR) in several formats: LAS, geodatabase, DEM and breaklines.

DNR staff created three additional products: two-foot contours, building outlines and hillshades.

Note: This metadata record was created at the Minnesota Geospatial Information Office by combining information supplied by AeroMetric and DNR.
Purpose The data was collected as part of the Minnesota Elevation Mapping Project, managed by the Minnesota Department of Natural Resources: www.mngeo.state.mn.us/committee/elevation/mn_elev_mapping.html
Time Period of Content Date 2010
Currentness Reference LiDAR data was collected during spring and fall leaf-off periods: April 8 - May 5 and November 2 - 19, 2010.
Progress Complete
Maintenance and Update Frequency Unknown
Spatial Extent of Data 25 counties in the Minnesota River Basin in southwest Minnesota (see Place Keywords)
Bounding Coordinates -96.628762
-93.401415
46.158043
43.417905
Place Keywords Minnesota, MN, Southwest Minnesota, Minnesota River Basin, Brown, Chippewa, Cottonwood, Douglas, Faribault, Jackson, Kandiyohi, Lac qui Parle, Le Sueur, Lincoln, Lyon, Martin, Murray, Nicollet, Nobles, Pipestone, Pope, Redwood, Renville, Rock, Sibley, Swift, Waseca, Watonwan, Yellow Medicine counties
Theme Keywords elevation, LiDAR, DEM, digital elevation model, contour, topographic, topo, DTM, LAS, breakline
Theme Keyword Thesaurus ISO 19115
Access Constraints None
Use Constraints See Disclaimer field for complete use conditions.
Contact Person Information Rob Merry,
AeroMetric, Inc.
4020 Technology Parkway
Sheboygan, WI  53083
Phone: 920-457-3631
Fax: 920-457-0410
Email: rmerry@aerometric.com
Browse Graphic None available
Associated Data Sets 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.
Logical Consistency N/A
Completeness Complete
Horizontal Positional Accuracy All area data products were acquired at or below 1700 meters above mean terrain (AMT) and have a horizontal accuracy of 0.30 meters, with a nominal point spacing of 1.3 meters.

The NAD83 (NSRS2007) datum was used.
Vertical Positional Accuracy The data was to meet a 15cm Vertical RMSE which was exceeded with values better than 10cm throughout the project.

The Fundamental Vertical Accuracy (FVA) of the Classified Bare Earth for all Areas achieved is 0.07 meters at a 95% confidence level in the 'Open Terrain' land cover category. 502 control points were used in this evaluation.

The accuracy statement is based on the area 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 the vertical accuracy or better, however, derived products may be less accurate in areas of dense vegetation due to a fewer number of points defining the bare-earth in these areas.

The NAVD88, Geoid03 vertical datum was used.
Lineage The LiDAR data was captured using multiple fixed wing aircraft equipped with a LiDAR system. Each LiDAR system includes a differential GPS unit and inertial measurement system to provide superior accuracy. A total of 107 flight missions were required to cover the 25 counties. Airborne accuracy was achieved using the State of Minnesota's Department of Transportation CORS network. Smooth best estimated trajectories (sbets) were generated using Applanix's POSPAC 4.4 as well as POS MMS software packages. LAS files were created using Optech's Dashmap, ASDA, and LMS software. Survey checkpoints were collected by AeroMetric to assist with the validation of the LiDAR point cloud. Point cloud classification and deliverables were created with Terrasolid's software suite package as well as ESRI's Arc software.

Acquisition parameters:
1. Scanner - Optech Gemini
2. Flight Height - 1700 meters above mean terrain
3. Scan Angle - 40 degrees
4. Sidelap - 50%
5. Nominal Post Spacing - 1.3 meters
6. Scan Frequency - 34 Hz

GPS and IMU processing parameters:
1. Processing programs and version - Applanix - POSGPS and POSProc, versions 4.4, MMS version 5.2
2. Maximum baseline length - Not greater than 60km
3. Number of base stations during LiDAR collection - A minimum of 1
4. Max separation between base stations during LiDAR collection - 0.05m
5. IMU processing monitored for consistency and smoothness - Yes

Point Cloud Processing:
1. Program and version - Optech ASDA, Dashmap
2. Horizontal Datum - NAD83(NSRS2007)
3. Horizontal Coordinates - Universal Transverse Mercator, Zone 15, in meters
4. Vertical Datum - NAVD88
5. Geoid Model used to reduce satellite-derived elevations to orthometric heights - NGS Geoid03

LIDAR Processing by AeroMetric:

1. Processing Programs and versions - TerraSolid TerraScan (version 010.021), TerraModeler (version 010.005 and TerraMatch (version 010.012) and Intergraph MicroStation (version.08.05.02.55).

2. Point Cloud data was imported to TerraScan in a Microstation V8 (V) CAD environment on a specified tiling scheme.

3. Analyze the data for overall completeness and consistency to ensure that there are no voids in the data collection.

4. Inspect for calibration errors in the dataset using the TerraMatch software. This was accomplished by sampling the data collected across all flight lines and classifying the individual lines to ground. The software will use 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 provided Quality Assurance and Quality Control (QA/QC) data for this project. AeroMetric captured QA/QC points in the 'open terrain' land cover category that were used to test the accuracy of the LiDAR ground surface. TerraScan's Output Control Report (OCR) was used to compare the QA/QC 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 QA/QC data, a bias adjustment was determined, and the results were applied (if necessary) to the LiDAR data. A final OCR was performed with a resulting RMSE of 0.088m for the project.

8. Once the automatic processing and the testing of LiDAR was complete, AeroMetric meticulously reviewed the generated bare-earth surface data to ensure that proper classification was achieved as part of a Quality Control process.

9. Breaklines were collected for all 25 counties. The criteria for breaklines were rivers that were 100 feet or larger with double lines and ponds that were 2 acres or larger. Breaklines were delivered as an ESRI feature class (PolygonZ format). Each shapefile contains georeference information. Breakline elevations use the same coordinate reference system as the LAS point cloud. Breaklines were delivered in tile format and edgematch seamlessly both vertically and horizontally. The tiling scheme was provided by the Minnesota Department of Natural Resources and is from the USGS 16th 1:24,000 quadrangle tiles.

10. Final deliverables were generated and output to the DNR-specified tiling scheme. Details for each format:

Point Cloud
Classified point cloud data was delivered in LAS v1.2. Georeference data is located in the LAS header. Each LiDAR point has a unique timestamp. Data was delivered in tile format without overlap.

Geodatabase
An ESRI geodatabase was created on a tile basis for all 25 counties. Each geodatabase has a feature dataset named Terrain Data which contains bare earth points, bridge breaklines, and hydro breaklines (if present). Each geodatabase also has a raster DEM that was generated from the LAS points and the breaklines. The raster DEM tiling scheme was an orthogonal setup based on the original tile scheme. Each geodatabase contains georeference information. The geodatabases use the same coordinate reference system as the LAS point cloud.

DEM
Bare Earth Surfaces (raster DEMs) were generated from the classified bare earth ground LiDAR point cloud for every tile of this 25 county project. DEMs were generated using the following criteria: Cell size 1 meter, delivered in ESRI 32-bit floating raster, tiled without overlap. Georeference data was included in the raster file. Depressions (sinks), natural or man-made were not filled as specified by the job specifications. Water bodies (ponds and lakes) and wide streams and rivers were hydro-flattened within the DEMs based on the following criteria: 2-acre water bodies or larger or flowing water nominally wider than 100 feet.

Breaklines
Breaklines were collected for all 25 counties. The criteria for breaklines were rivers that were 100 feet or larger with double lines and ponds that were 2 acres or larger. Breaklines were delivered as an ESRI feature class (PolygonZ format). Each shapefile contains georeference information. Breakline elevations use the same coordinate reference system as the LAS point cloud. Breaklines were delivered in tile format and edge match seamlessly both vertically and horizontally.


Additional Products Generated by Minnesota DNR staff:

These products 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
Horizontal Datum NAD83
Horizontal Units meters

Section 5 Attributes
Overview The classification scheme of the LiDAR point cloud:
1 = unclassified
2 = bare earth ground
4 = vegetation
6 = buildings
7 = noise
8 = model keypoints
9 = water
10 = ignored ground
14 = bridges
Detailed Citation
Table Detail:

Section 6 Distribution
Publisher Minnesota Department of Natural Resources
Publication Date 2011
Contact Person Information Nancy Rader, GIS Data Coordinator
Minnesota Geospatial Information Office (MnGeo)
658 Cedar Street, Room 300
St. Paul, MN  55155
Phone: 651-201-2489
Fax: 651-296-6398
Email: gisinfo.mngeo@state.mn.us
Distributor's Data Set Identifier MN River Basin LiDAR 2010
Distribution Liability 1. The Minnesota Department of Natural Resources General Geographic Data License Agreement is online: www.dnr.state.mn.us/sitetools/data_software_license.html

2. MnGeo's data disclaimer is online: www.mngeo.state.mn.us/chouse/disclaimer.html
Ordering Instructions The LiDAR data provided by DNR may be viewed online or downloaded in several ways:

1. MnTOPO website: www.dnr.state.mn.us/maps/mntopo/index.html (or click the link below in the Online Linkage field)

- view data online
- download data in Esri and open formats (tiles for most data formats will be mosaicked together during download)
- see the help file for details: files.dnr.state.mn.us/aboutdnr/gis/mntopo/mntopo_help_document.pdf

2. MnGeo's FTP site
Use the tile_index.pdf maps to locate the tiles you need. Except for the county file, tiles will not be mosaicked.

a. From the county folder: ftp.lmic.state.mn.us/pub/data/elevation/lidar/county/
The county mosaics are named elevation_data.gdb.zip For details of their contents and size, see this table: geoint.lmic.state.mn.us/lidar.php

b. In the 250k tiles folder: ftp.lmic.state.mn.us/pub/data/elevation/lidar/q250k/


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
Metadata Date 04/28/2014
Contact Person Information Nancy Rader, GIS Data Coordinator
Minnesota Geospatial Information Office (MnGeo)
658 Cedar Street, Room 300
St. Paul, MN  55155
Phone: 651-201-2489
Fax: 651-296-6398
Email: gisinfo.mngeo@state.mn.us
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


This page last updated: 04/28/2014
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