Metadata: Digital Orthoimagery, Twin Cities, Minnesota, Spring 2016, 1-ft Resolution

Digital Orthoimagery, Twin Cities, Minnesota, Spring 2016, 1-ft Resolution

This page last updated: 04/01/2016
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:Metropolitan Council, Surdex Corporation

Title: Digital Orthoimagery, Twin Cities, Minnesota, Spring 2016, 1-ft Resolution

Abstract: This dataset contains leaf-off, 4-band (red, green, blue, near-infrared (RGBI)) digital orthophoto imagery of the Twin Cities metropolitan area in east-central Minnesota. 268 digital orthophoto quarter quadrangle (DOQQ) tiles were produced at 30-cm (1-foot) resolution from new aerial photography captured in the spring of 2016. The counties of Hennepin, Ramsey and Washington were originally captured at 30-cm resolution. DOQQ tiles covering Anoka, Carver, Dakota and Scott counties were created from higher resolution 15-cm (6-inch) imagery and resampled down to 30-cm resulting in a uniform resolution for the entire project area.

Project partners include the Metropolitan Council, the Minnesota IT Services' Geospatial Information Office (MnGeo), the Metropolitan Mosquito Control District, and Anoka, Carver, Dakota and Scott counties.

This dataset is available for direct use via the MnGeo Geospatial Image Service (Twin Cities metro layer). More information at http://www.mngeo.state.mn.us/chouse/wms/geo_image_server.html

This metadata record was created by MnGeo using information supplied by Surdex Corporation, the Metropolitan Council and the Minnesota Department of Transportation.

Purpose: To produce four-band, leaf-off digital ortho-rectified aerial photography acquired in the spring of 2016 for the purpose of updating generalized land use data for the Twin Cities metropolitan area as well as for many other mapping and analysis functions.

Time Period of Content Date: 04/01/2016

Currentness Reference: Ground condition. Image acquisition dates: April 9, 12, 13, 15 and 22, 2016.

Progress: Complete

Maintenance and Update Frequency: The Metropolitan Council is required to collect Generalized Land Use data at the same time as the Census. The Metropolitan Council plans to acquire aerial imagery again in 2020.

Spatial Extent of Data: 7-county Twin Cities metro: Anoka, Carver, Dakota, Hennepin, Ramsey, Scott and Washington counties, Minnesota

Bounding Coordinates: -94.34
-92.62
45.75
44.43

Place Keywords: Minnesota, MN, Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, Washington, Twin Cities

Theme Keywords: imageryBaseMapsEarthCover, Orthophotography, Digital Orthophotography, Ortho, Orthophotos, Digital Orthorectified Images, Digital Orthophotos, DOQ, DOQQ, Imagery, Images, Aerial Photography, Aerial Photos, Digital Aerial Photography, Air Photo, Color Infrared, Four Band Imagery

Theme Keyword Thesaurus: ISO 19115 Topic Category

Access Constraints: None. This dataset is public domain under the Minnesota Government Data Practices Act (Minnesota Statutes Chapter 13). If the dataset is not available from the Online Linkage in Section 6, please contact the Distribution Contact Person.

Use Constraints: None. This dataset is public domain under the Minnesota Government Data Practices Act (Minnesota Statutes Chapter 13).

Contact Person Information: Tanya Mayer, GIS Specialist
Metropolitan Council
390 Robert Street North
St. Paul, MN  55101-1805
Phone: 651.602.1604
Email: tanya.mayer@metc.state.mn.us

Browse Graphic: Click to view a data sample.


Associated Data Sets: For information on other air photos available for Minnesota, see: http://www.mngeo.state.mn.us/chouse/airphoto/

Section 2: Data Quality

Attribute Accuracy: N/A

Logical Consistency: N/A

Completeness: Created using native 30-cm GSD and resampled 15-cm GSD for a complete 30-cm resolution data set over 7 counties in the metropolitan Minneapolis/St. Paul area. The counties of Anoka, Carver, Dakota and Scott were originally collected at a 15-cm GSD and resampled to 30-cm. Imagery for Hennepin, Ramsey and Washington counties were originally collected at a 30-cm GSD.

Horizontal Positional Accuracy: Meets the ASPRS horizontal accuracy standard for 30-cm GSD at Standard Mapping Accuracy of 60-cm adhering to NSSDA guidelines and specifications. Surdex collected new survey control in UTM NAD 1983(2011) Zone 15N, meters with Geoid model 12a, along with existing County Survey and Airborne GPS data at the time of image acquisition and was used exclusively to control the product to ground coordinates.

Vertical Positional Accuracy: None - this is a horizontal-only product.

Lineage: Aircraft were deployed to the Twin Cities area in April 2016 for digital image acquisition during the requested time frame. Multiple Cessna Conquest equipped with Leica ADS100 (Digital Mapping Cameras) captured 4-band imagery over the entire project area of interest with 157 north-south flight lines planned, utilizing 30 percent side-lap (38 percent side-lap in the 2 downtown areas). The dates of image acquisition were 4/9/2016, 4/12/2016, 4/13/2016, 4/15/2016 and 4/22/2016.

Imagery for Hennepin, Ramsey and Washington counties were collected at a 30-cm GSD. The counties of Anoka, Carver, Dakota and Scott were collected at a 15-cm GSD and were later resampled to 30-cm for a complete seven-county 30-cm resolution dataset. Imagery was captured at an altitude of 6,200 feet and 12,400 feet above mean terrain, allowing small amounts of cloud conditions.

Four bands (RGBI, natural color plus near infrared) of raw camera data were processed by Surdex using Leica X Pro software coupled with Surdex proprietary image handling software for color correction and dodging. Post processing of Airborne and Ground GPS data was performed with Waypoint Consulting's GrafNav software. Aerial Triangulation was completed in UTM NAD 1983(2011) Zone 15N, using Leica X Pro Automatic Triangulation and rectification of imagery to the client-supplied DEM was completed using Surdex proprietary software with LiDAR DEM provided by Minnesota IT Services. Image mosaicking, QC and final DOQQ tiled products were produced using proprietary Surdex software.

Shortly after orthoimagery production began Surdex provided two representative sample areas of data to project stakeholders for processing evaluation and standardization. This quality control pilot project allowed all subsequent processing to be controlled by client-established color balance parameters.

All post processed orthoimagery was systematically reviewed by stakeholders via Surdex's web-based Client Product Acceptance Tool (CPAT) which allowed edit calls to be communicated to the vendor online. Approximately 230 user edit call were addressed. Upon repair and reexamination of all stakeholder edit calls, Surdex physically delivered the orthoimagery data on hard drive.

Those data were then tested for horizontal positional accuracy by MnDOT's Office of Land Management Survey and Mapping Section staff. A project area accuracy measure was calculated using 252 independent survey control points, yielding an RMSE of 33.83-cm (1.11 feet), meeting the ASPRS-specified threshold for Standard Mapping and GIS work of <=60-cm (1.97-feet).

The final data is in UTM NAD83 (2011) Zone 15 projection.

The original data was delivered in GeoTIFF format only.

The imagery is available to the general public only as a web map service (WMS) on MnGeo's Geospatial Image Service (see ordering instructions below).

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

Vertical Datum:

Vertical Units:

Depth Datum:

Depth Units:

Cell Width: 0.3

Cell Height: 0.3

Section 5: Attributes

Overview: Imagery in 4 Bands with the order of Red, Green, Blue and Near Infrared.

Detailed Citation:

Table Detail:

Section 6: Distribution

Publisher: Minnesota Geospatial Information Center (MnGeo)

Publication Date:

Contact Person Information: Tanya Mayer, GIS Specialist
Metropolitan Council
390 Robert Street North
St. Paul, MN  55101-1805
Phone: 651.602.1604
Email: tanya.mayer@metc.state.mn.us

Distributor's Data Set Identifier: base_metro_orthos_2016

Distribution Liability: MnGeo's data disclaimer is online: http://www.mngeo.state.mn.us/chouse/disclaimer.html

Ordering Instructions: These ortho images are very large and thus are not provided online for download. Instead, they are available to view as a web map service (WMS), part of MnGeo's Geospatial Image Service. Click on the link below for more information about the Geospatial Image Service and how to use web map services.

Online Linkage:Download Page

Section 7: Metadata Reference

Metadata Date: 04/01/2016

Contact Person Information: Tanya Mayer, GIS Specialist
Metropolitan Council
390 Robert Street North
St. Paul, MN  55101-1805
Phone: 651.602.1604
Email: tanya.mayer@metc.state.mn.us

Metadata Standard Name: Minnesota Geographic Metadata Guidelines

Metadata Standard Version: 1.2



This page last updated: 04/01/2016
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