LiDAR Elevation, McLeod County, Minnesota, 2007

This page last updated: 08/15/2012
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 McLeod County Highway Department
Title LiDAR Elevation, McLeod County, Minnesota, 2007
Abstract One-foot contours in ESRI file geodatabase format divided into files sized approximately to 1/4 township areas. Bare-earth and first-return LiDAR data divided into 5000' X 5000' sheet tiles named according to the Lower Left XY coordinate value in LAS format. Five foot posted raster bare-earth DEM divided into 5000' X 5000' sheet tiles. Raster DEM in ArcGrid format, Countywide breaklines compiled as needed using synthetic stereopairs generated from the LiDAR intensity data in ESRI file geodatabase and ESRI shape file format.

The LiDAR data for McLeod County was collected under contract by the county. Thus, the data format is not entirely consistent with some of the other LiDAR data collected by the State of Minnesota. Specifically, the McLeod County collect required classification of only Bare Earth in the LiDAR LAS files, so there is no information on buildings, vegetation, or model key points.

The LAS data used for this process were acquired from the USGS.

No breaklines were available for processing this data.

Note: This metadata record was created at the Minnesota Geospatial Information Office using information supplied by McLeod County and the Minnesota Department of Natural Resources.
Purpose The bare-earth data and breakline data was utilized to produce terrain surface models for the generation of the one-foot contours and the raster DEM.
Time Period of Content Date 2007
Currentness Reference
Progress Complete
Maintenance and Update Frequency Unknown
Spatial Extent of Data McLeod County, Minnesota
Bounding Coordinates -94.506402
-93.977849
44.982573
44.625869
Place Keywords McLeod County, Minnesota
Theme Keywords elevation, LiDAR, DEM, digital elevation model, contour, topographic, topo, DTM, LAS, breakline
Theme Keyword Thesaurus ISO 19115
Access Constraints None.
Use Constraints The topographic data represents the results of data collection/processing for McLeod County and indicates the existing general conditions. As such, they are only valid for their intended use, content, time and accuracy specifications. The user is responsible for the results of any application of data other than its intended purposes.

See Disclaimer field for complete use conditions.

Contact Person Information Christy Christensen, GIS Director
McLeod County
1400 Adams St. SE
Hutchinson, MN  55350
Phone: 320-234-0230
Email:
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 LiDAR DEM Quality Control Report
Logical Consistency LiDAR was classified and stereo-pairs were generated from LiDAR intensity data which were used to collect breaklines. A surface was generated from the bare earth LiDAR DTM and the collected breakline data to produce one-foot contours and raster DEM at a 5-foot resolution.
Completeness Data collection of the survey area resulted in a total of 124 flightlines including re-flights and supplemental flights as well as four control lines covering the project area. The range files, flight logs, raw air and ground GPS files were then processed using REALM, a LIDAR processing software package from Optech. Processing began by downloading these files into a REALM database. For redundancy and accuracy purposes, the airborne GPS data were processed from two base stations using POSGPS from Applanix, Inc. The agreement between a minimum of two solutions checked or combined between a minimum of two stations was better than 10 cm in each of X, Y, and Z. These trajectories were used in the processing of the inertial data. The inertial data were processed using POSProc from Applanix, Inc. This software produces an SBET ('smooth best estimate of trajectory') using the GPS trajectory from POSGPS and the roll, pitch and heading information recorded by the POS (Position Orientation System). REALM uses the SBET to generate a set of data points for each laser return in the LAS file format. Each data point is assigned an echo value so it can be segregated based on the first and last pulse information. This project's data were processed in strip form, meaning each flight line was processed independently. Processing the lines individually provides the data analyst with the ability to QC the overlap between lines.
Horizontal Positional Accuracy
Lineage Vendor Processing Steps:

Strips were imported into a project using TerraScan (Terrasolid, Ltd.) and the project management tool GeoCue (GeoCue Corp.). By creating a project the various flightlines are combined while breaking the dataset as a whole into manageable pieces. This process also converted the dataset from geographic coordinates to the Minnesota County Coordinate System (NAD83), McLeod Co utilizing NADCON. The ellipsoid height values were converted to NAVD88 orthometric values using Geoid03, provided by NGS. Individual lines were then checked against adjacent lines to ensure a cohesive dataset. The data from each line were then combined and a classification routine was then run to determine the initial surface model. This initial surface model was then reduced using Optimal Geomatics' proprietary methods to create the final bare-earth dataset. A Triangular Irregular Network (TIN) was generated using the final surface data. Contours were then created from the TIN. The bare-earth data were then checked against the validation points across the project area. The results of these checks showed the DEM fitting the validation points well (see LIDAR DEM Quality Control Report for results). Stereo pairs were generated from the LIDAR intensity data using Geocue and LIDAR1CuePac (Geocue Corp.). LIDARgrammetry was then utilized to collect breaklines where necessary along hydro features to support the contour generation. These breaklines were collected as a 3D element in the MicroStation (Bentley Systems, Inc.) environment utilizing ISSD (Z/I Imaging). The deliverables constituted: LIDAR bare-earth in .LAS format, LIDAR first-return in .LAS format, raster bare-earth DEM in ESRI ArcGRID format at 5-foot resolution, and an ArcGIS File Geodatabase containing one-foot topographic contour data, breaklines, and control points as 3D feature classes.


Minnesota Department of Natural Resources Processing Steps:

1) LAS files were projected from County Coordinates to UTM Zone 15, NAD83
2) LAS point Z values were scaled from feet to meters
3) LAS files were retiled into the state tile scheme (1/16 of a USGS 1:24,000 scale quadrange)
4) Breakline features were merged together into a single feature class
5) Breakline features were projected from County Coordinates to UTM Zone 15, NAD83
6) Breakline Z Values were scaled from feet to meters
7) LAS Bare Earth Points and breaklines were used to create a Terrain data type
8) 1-meter DEM was derived from Terrain using natural neighbors interpolation option (DEM01)
9) Hillshade was derived from 1-meter DEM (DEM01HS)
10) 3-meter DEM was derived from Terrain using natural neighbors interpolation option (DEM03)
11) Hillshade was derived from 3-meter DEM (DEM03HS)
12) Aspect was derived from 3-meter DEM (DEM03ASPECT)
13) Slope in degrees was derived from 3-meter DEM (DEM03SLOPE_DEGREES)
14) Slope in percent was derived from 3-meter DEM (DEM03SLOPE_PERCENT)
15) DEM03 was smoothed using a 3x3 mean smoothing filter
16) 2-foot contours were created from the smoothed 3-meter DEM


All processing was done using ArcGIS V10 and LP360 Extensions

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 Item Name: Type Definition: String,50
Item Name: Fcode Double, Scale 0
Item Name: Elevation Double, Scale 3

Index Contour: Every Fifth Contour of the One Foot Contour Dataset
Intermediate Contour: Contours depicted between Index Contours.
Index Depression Contour: Every Fifth Depression Contour of the One Foot Contour Dataset
Intermediate Depression Contour: Depression Contours depicted between Index Contours.
Detailed Citation
Table Detail:

Section 6 Distribution
Publisher
Publication Date
Contact Person Information Nancy Rader, GIS Data Coordinator
Minnesota Geospatial Information Office
658 Cedar Street
St. Paul, MN  55155
Phone: 651-201-2489
Email: clearing.house@state.mn.us
Distributor's Data Set Identifier Downloadable Data
Distribution Liability The digital vector data represents the results of data collection/processing for McLeod County, MN and indicates the general conditions existing at the time of flight. As such, it is only valid for its intended use, content, time and accuracy specifications. The user is responsible for the results of any application of the data other than for its intended purpose.

MnGeo's data disclaimer is online: www.mngeo.state.mn.us/chouse/disclaimer.html
Ordering Instructions The LiDAR data provided by DNR may be downloaded from an FTP site maintained by MnGeo by clicking on the link below (recommended) or from DNR's FTP site which is not as fast. DNR provides the data as well as numerous help files on the site to assist with understanding LiDAR data and using it with GIS software.

For more help with Minnesota's LiDAR data, including a link to DNR's FTP site, 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 08/15/2012
Contact Person Information Nancy Rader, GIS Data Coordinator
Minnesota Geospatial Information Office
658 Cedar Street
St. Paul, MN  55155
Phone: 651-201-2489
Email: clearing.house@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: 08/15/2012
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