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Washington County, MN - Orthoimages

This page last updated: 04/18/2017 
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Metadata Summary

Originator	Survey Division - Washington County Public Works
Abstract	This task order consists of digital orthophoto production covering the Washington County, Minnesota area. The data set consists of 0.5-foot pixel resolution three band orthoimages. The data is projected in NAD 1983 Washington County Coordinate System 1986 - US Survey Feet
Browse Graphic	none available
Time Period of Content Date
Currentness Reference	ground condition
Access Constraints	None
Use Constraints	None. However, 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be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions.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.
Distributor Organization
Ordering Instructions
Online Linkage	none available

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Full Metadata

Washington County, MN - Orthoimages

Go to Section:
1. Identification Information
2. Data Quality Information
3. Spatial Data Organization Information
4. Spatial Reference Information
5. Entity and Attribute Information
6. Distribution Information
7. Metadata Reference Information

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Section 1	Identification Information			Top of page
Originator	Survey Division - Washington County Public Works
Title	Washington County, MN - Orthoimages
Abstract	This task order consists of digital orthophoto production covering the Washington County, Minnesota area. The data set consists of 0.5-foot pixel resolution three band orthoimages. The data is projected in NAD 1983 Washington County Coordinate System 1986 - US Survey Feet
Purpose	This data depicts geographic features on the surface of the earth.
Time Period of Content Date
Currentness Reference	ground condition
Progress	Complete
Maintenance and Update Frequency	irregular
Spatial Extent of Data	Dates of Acquisition: Imagery was collected on April 14, 2016, April 15, 2016; April 23, 2016; April 30, 2016; May 2, 2016; May 3, 2016. The imagery for this project was flown at a nominal acquisition altitude (AGL) of 6,800 feet. Differential baseline lengths were kept to a minimum by the use of the nearest available CORS stations to the project area. GPS coordinates were referenced to the National Spatial Reference System (NSRS) through connections to active CORS and/or passive monumented control stations. The digital camera was calibrated by the manufacturer and the camera parameters refined through in-situ proprietary procedures.
Bounding Coordinates	-93.0463817980985 -92.7184328285402 45.2984718935024 44.7299076459292
Place Keywords	US
Theme Keywords	0.5 foot orthoimage
Theme Keyword Thesaurus	None
Access Constraints	None
Use Constraints	None. However, 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.
Contact Person Information	John Baer, Survey Project Coordinator Survey Division - Washington County Public Works 11660 Myeron Road North Stillwater, MN 55082 Phone: 651-430-6883 FAX: E-mail: john.baer@co.washington.mn.us
Browse Graphic	none available
Browse Graphic File Description
Associated Data Sets
Section 2	Data Quality Information		Top of full metadata	Top of page
Attribute Accuracy	Radiometry is verified by visual inspection of the digital orthophoto. Slight systematic radiometric differences may exist between adjacent orthoimage files; these are due primarily to differences in source image capture dates and sun angles along flight lines. These differences can be observed in an image's general lightness or darkness when it is compared to adjacent orthoimage file coverages. Tonal balancing may be performed over a group of images during the mosaicking process which may serve to lighten or darken adjacent images for better color tone matching.
Logical Consistency	Orthophotos conform to the specifications set forth by Washington County for this contract. Data cover the entire area specified for this project. All GeoTIFF tagged data and image file sizes are validated using commercial GIS software to ensure proper loading before being archived. This validation procedure ensures correct physical format and field values for tagged elements. Seamlines and tile edges are visually inspected. Seamline mismatches are not corrected unless the overall displacement exceeds one meter.
Completeness	Orthoimages are visually inspected for completeness to ensure that no gaps or image misplacements exist within and between adjacent images. These images are derived by mosaicking multiple images to ensure complete coverage. Source imagery is cloud free.
Horizontal Positional Accuracy	The horizontal accuracy of the orthorectified images is mainly determined by the quality of the DEM. The elevation data was existing LiDAR data provided by the state of Minnesota website. Airborne GPS/IMU data was used. All photo identifiable checkpoints were measured and compared to the surveyed checkpoints to determine the RMSE. All rectified chip overlap was checked for mismatch. Final imagery was cut into client supplied tiles for delivery.
Lineage	Digital aerial imagery was obtained using a large format Leica ADS 100 camera equipped with Airborne GPS/IMU covering the AOI. The imagery was collected during leaf off conditions in the spring of 2016 under conditions free from clouds and cloud shadows, smoke, fog, haze, light streaks, snow, ice on water bodies, foliage, flooding, and excessive soil moisture. The sun angle threshold was 30 degrees. The imagery consisted of panchromatic, blue, green, red and near infrared bands. The three color bands and near infrared bands have been pan sharpened and archived as frame imagery.
Source Scale Denominator
Section 3	Spatial Data Organization Information		Top of full metadata	Top of page
Native Data Set Environment	Leica MissionPro; PhotoShop; MicroStation; ArcGIS 10.3; MicroStation Version 8; TerraScan; TerraModeler; GeoCue; Esri ArcGIS; Global Mapper 16; Leica Cloud Pro 1.2; Windows 10 Operating System
Geographic Reference for Tabular Data
Spatial Object Type
Vendor Specific Object Types
Tiling Scheme
Section 4	Spatial Reference Information		Top of full metadata	Top of page
Horizontal Coordinate Scheme
Ellipsoid	GRS 1980
Horizontal Datum
Horizontal Units	Foot_US
Distance Resolution
Cell Width	0.5
Cell Height	0.5
Map Projection Name	NAD 1983 Washington County Coordinate System 1986 - US Survey Feet
Section 5	Entity and Attribute Information		Top of full metadata	Top of page
Entity and Attribute Overview	Natural color orthoimagery is organized in three color bands or channels which represent the red, green, and blue portions of the spectrum. Each image pixel is assigned a triplet of numeric values, one for each color band. Numeric values range from 0 to 255. There are no void areas.
Entity and Attribute Detailed Citation	U.S. Department of the Interior, U.S. Geological Survey, 1996, Standards for Digital Orthophotos: Reston, VA.
Section 6	Distribution Information		Top of full metadata	Top of page
Publisher	Washington County, Minnesota
Publication Date	2016
Contact Person Information	, Phone: FAX: E-mail: none available
Distributor's Data Set Identifier
Distribution Liability
Transfer Format Name
Transfer Format Version Number
Transfer Size
Ordering Instructions
Online Linkage	none available
Section 7	Metadata Reference Information		Top of full metadata	Top of page
Metadata Date	07/27/2016
Contact Person Information	John Baer, Survey Project Coordinator Survey Division - Washington County Public Works 11660 Myeron Road North Stillwater, MN 55082 Phone: 651-430-6883 FAX: E-mail: john.baer@co.washington.mn.us
Metadata Standard Name
Metadata Standard Version	FGDC-STD-001-1998
Metadata Standard Online Linkage

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This page last updated: 04/18/2017