The Iowa LiDAR Project - LAS and ASCII Files
Metadata also available as
Metadata:
- Identification_Information:
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- Citation:
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- Citation_Information:
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- Originator: Iowa LiDAR Consortium
- Title: The Iowa LiDAR Project - LAS and ASCII Files
- Publication_Information:
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- Publisher: Iowa Lidar Consortium
- Description:
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- Abstract:
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This is collection level metadata for LAS and ASCII data files from the statewide Iowa Lidar Project. The Iowa Light Detection and Ranging (LiDAR) Project collects location and elevation (X, Y, Z) data to a set standard for the entire state of Iowa.
LIDAR is defined as an airborne laser system, flown aboard rotary or fixed-wing aircraft, that is used to acquire x, y, and z coordinates of terrain and terrain features that are both manmade and naturally occurring. LIDAR systems consist of a light-emitting scanning laser, an airborne Global Positioning System (GPS) with attendant GPS base station(s), and an Inertial Measuring Unit (IMU).
The laser scanning system measures ranges from the scanning laser to terrain surfaces by measuring the time it takes for the emitted light (LIDAR return) to reach the earth's surface and reflect back to the onboard LIDAR detector.
The airborne GPS system ascertains the in-flight three-dimensional position of the sensor, and the IMU delivers precise information about the attitude of the sensor. The LIDAR system incorporates data from these three subsystems to produce a large cloud of points on the land surface whose X, Y, and Z coordinates are known within the specified accuracy.
This collection consists of ASCII files of bare earth elevations and intensity (x,y,z,i) and, LAS (version 1.0 lidar data interchange standard) binary files that include all 1st and last returns, intensity and bare earth classification.
- Purpose:
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This digital, geographically referenced data set was developed by the Iowa
Department of Natural Resources to carry out agency responsibilities related
to management, protection, and development of Iowa's natural resources.
- Time_Period_of_Content:
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- Time_Period_Information:
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- Range_of_Dates/Times:
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- Beginning_Date: 2007
- Ending_Date: ongoing
- Currentness_Reference: ground condition
- Status:
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- Progress: Complete
- Maintenance_and_Update_Frequency: None planned
- Spatial_Domain:
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- Bounding_Coordinates:
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- West_Bounding_Coordinate: -96.684901
- East_Bounding_Coordinate: -90.069432
- North_Bounding_Coordinate: 43.557019
- South_Bounding_Coordinate: 40.332776
- Keywords:
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- Theme:
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- Theme_Keyword_Thesaurus: ISO 19115 Topic Category
- Theme_Keyword: elevation
- Theme:
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- Theme_Keyword_Thesaurus: None
- Theme_Keyword: LiDAR
- Theme_Keyword: Light Detection and Ranging
- Theme_Keyword: elevation
- Theme_Keyword: LAS file
- Theme_Keyword: ASCII file
- Place:
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- Place_Keyword_Thesaurus: GNIS
- Place_Keyword: Iowa
- Access_Constraints: None
- Use_Constraints:
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The development of the coverages in the NRGIS Library represents a major
investment of staff time and effort. As a professional responsibility, the Iowa
DNR expects to receive proper credit when these GIS coverages are utilized.
he Department also expects that the original documentation will remain with
any redistribution of these coverages.
- Point_of_Contact:
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- Contact_Information:
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- Contact_Person_Primary:
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- Contact_Person: Chris Ensminger
- Contact_Organization: Iowa Department of Natural Resources
- Contact_Address:
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- Address_Type: mailing and physical address
- Address: 502 East 9th
- City: Des Moines
- State_or_Province: IA
- Postal_Code: 50319
- Contact_Voice_Telephone: 515.281.4216
- Contact_Electronic_Mail_Address: chris.ensminger@dnr.iowa.gov
- Data_Set_Credit:
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The Iowa Lidar Consortium consists of the Iowa Department of Agriculture and Land Stewardship, Iowa Department of Natural Resources, Iowa Department of Transportation, the USDA Natural Resources Conservation Service (NRCS), and the US Geological Survey (USGS).
- Security_Information:
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- Security_Classification_System: State of Iowa Enterprise Data Classification Standard
- Security_Classification: Public
- Data_Quality_Information:
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- Logical_Consistency_Report: None
- Completeness_Report:
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Data will continue to be collected until a complete set is obtained. See the Cross-referece citations for files that track the completeness of the project.
- Positional_Accuracy:
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- Horizontal_Positional_Accuracy:
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- Horizontal_Positional_Accuracy_Report:
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LiDAR data are currently undergoing quality assurance testing by the U.S. Geological Survey (USGS).
While this testing is underway, these data are being provided as-is, with no guarantee of accuracy.
If USGS testing indicates data do not meet accuracy specs, those data will immediately be removed from distribution.
Until USGS certification is received, users should verify data accuracies for themselves.
Standard LiDAR Specifications:
-Sanborn prepares flight plans as parallel flight lines with at least one cross flight line to assure positional accuracy and quality control.
-Sanborn uses only automated filtering for Standard LiDAR products with the following minimum performance for bare earth elevation models:
-89% of artifacts or more removed depending on terrain and vegetation
-90% of all outliers removed
-90% of all vegetation removed
-93% of all buildings removed
-1.4 meter average point spacing
-Scan frequency and angles based on project area terrain and landcover
-1 meter RMSE
-No independent field verification
FEMA Compliant LiDAR Specifications:
-Sanborn flight plans are parallel flight lines with at least one cross flight line to assure positional accuracy and quality control, and collection verified with both kinematic and static collections.
-Sanborn uses automated and manual filtering for LiDAR products with the following minimum performance for bare earth elevation models:
-90% of artifacts or more removed depending on terrain and vegetation
-95% or better of all outliers removed
-95% of all vegetation removed
-98% of all buildings removed
In addition to Standard LiDAR specifications:
-Sanborn field verification
-3 classes, 20 pts. each
- Vertical_Positional_Accuracy:
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- Vertical_Positional_Accuracy_Report:
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Standard LiDAR Specifications: +/- 18 cm
Bare Earth: 18.5 cm RMSE
Vegetation: 37 cm RMSE
- Lineage:
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- Process_Step:
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- Process_Description:
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Data Collection:
Using a LH Systems ALS50 Light Detection And Ranging (LiDAR) system, flight lines of standard density (1.4 meter ground sample distance) data were collected over areas in Iowa. Multiple returns were recorded for each laser pulse along with an intensity value for each return. During the LIDAR campaign, the Sanborn field crew conducted a GPS field survey to establish final coordinates of the ground base stations for final processing of the base-remote GPS solutions.
- Process_Date: Unknown
- Process_Contact:
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- Contact_Information:
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- Contact_Person_Primary:
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- Contact_Person: Jamie Young
- Contact_Organization: Sanborn Map Company, Inc.
- Contact_Position: LiDAR Manager
- Contact_Address:
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- Address_Type: mailing and physical address
- Address: 1935 Jamboree Drive #100
- City: Colorado Springs
- State_or_Province: CO
- Postal_Code: 80920
- Contact_Voice_Telephone: 719.264.5602
- Contact_Facsimile_Telephone: 719.264.5637
- Contact_Electronic_Mail_Address: jyoung@sanborn.com
- Process_Step:
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- Process_Description:
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Airborne GPS Processing:
Airborne GPS data was differentially processed and integrated with the post processed IMU data to derive a smoothed best estimate of trajectory (SBET). The SBET was used to reduce the LiDAR slant range measurements to a raw reflective surface for each flight line. The overlap between flight lines was removed to provide a homogeneous coverage, and the coverage was classified to extract a bare earth digital elevation model (DEM).
Airborne GPS is differentially processed using the GrafNAV V7.50 software by Waypoint Consulting of Calgary, Alberta, Canada. The PDOP and distance separation is as follows:
IMU data is processed using the PosPac V4.2 software by Applanix Corporation of Richmond Hill, Ontario, Canada.
The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia.
The classification and quality control (QC) of LiDAR data is carried out using TerraScan software by Terrasolid Limited of Helinski, Finland.
- Process_Date: Unknown
- Process_Step:
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- Process_Description:
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IMU data Processing:
IMU data provides information concerning roll, pitch and yaw of collection platform during collection event. IMU information allows the pulse vector to be properly placed in 3D space allowing the distance from the aircraft reference point to be properly positioned on the elevation model surface. IMU data is processed using the PosPac V4.2 software by Applanix Corporation of Richmond Hill, Ontario, Canada.
- Process_Date: Unknown
- Process_Step:
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- Process_Description:
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LIDAR Point Classification
The classification and quality control (QC) of LiDAR data is carried out using TerraScan software by Terrasolid Limited of Helinski, Finland.
- Process_Date: Unknown
- Process_Step:
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- Process_Description:
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Output LAS Files and ASCII
The product output of LiDAR data is carried out using TerraScan software by Terrasolid Limited of Helinski, Finland.
- Process_Date: Unknown
- Spatial_Reference_Information:
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- Horizontal_Coordinate_System_Definition:
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- Planar:
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- Grid_Coordinate_System:
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- Grid_Coordinate_System_Name: Universal Transverse Mercator
- Universal_Transverse_Mercator:
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- UTM_Zone_Number: 15
- Transverse_Mercator:
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- Scale_Factor_at_Central_Meridian: 0.999600
- Longitude_of_Central_Meridian: -93.000000
- Latitude_of_Projection_Origin: 0.000000
- False_Easting: 500000.000000
- False_Northing: 0.000000
- Planar_Coordinate_Information:
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- Planar_Coordinate_Encoding_Method: coordinate pair
- Coordinate_Representation:
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- Abscissa_Resolution: 0.001024
- Ordinate_Resolution: 0.001024
- Planar_Distance_Units: meters
- Geodetic_Model:
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- Horizontal_Datum_Name: North American Datum of 1983
- Ellipsoid_Name: Geodetic Reference System 80
- Semi-major_Axis: 6378137.000000
- Denominator_of_Flattening_Ratio: 298.257222
- Vertical_Coordinate_System_Definition:
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- Altitude_System_Definition:
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- Altitude_Datum_Name: North American Vertical Datum of 1988
- Altitude_Distance_Units: meters
- Altitude_Encoding_Method:
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Explicit elevation coordinate included with horizontal coordinates
- Distribution_Information:
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- Distributor:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: University of Northern Iowa, GeoTREE Center
- Resource_Description: Downloadable Data
- Distribution_Liability:
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All data available on this site are currently undergoing quality assurance testing by the U.S. Geological Survey (USGS). While this testing is underway, this data are being provided as-is, with no guarantee of accuracy. If USGS testing indicates data do not meet accuracy specs, those data will immediately be removed from this site. Until USGS certification is received, users should verify data accuracies for themselves.
- Standard_Order_Process:
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- Digital_Form:
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- Digital_Transfer_Information:
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- Format_Name: ASCII and LAS files
- File_Decompression_Technique: 7zip
- Digital_Transfer_Option:
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- Online_Option:
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- Computer_Contact_Information:
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- Network_Address:
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- Network_Resource_Name: <http://geotree2.geog.uni.edu/lidar/>
- Fees: None
- Turnaround: Immediate
- Metadata_Reference_Information:
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- Metadata_Date: 20090129
- Metadata_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Iowa Geological Survey, DNR
- Contact_Person: GIS Librarian
- Contact_Address:
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- Address_Type: Mailing and Physical
- Address: 109 Trowbridge Hall
- City: Iowa City
- State_or_Province: IA
- Postal_Code: 52242-1319
- Contact_Voice_Telephone: 319-335-1575
- Contact_Electronic_Mail_Address: gis_library@igsb.uiowa.edu
- Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
- Metadata_Standard_Version: FGDC-STD-001-1998
- Metadata_Time_Convention: local time
- Metadata_Access_Constraints: None
- Metadata_Use_Constraints: None
- Metadata_Extensions:
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- Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>
- Profile_Name: ESRI Metadata Profile
Generated by mp version 2.9.6 on Thu Jan 29 10:39:54 2009