USGS High Resolution Orthoimagery, Minneapolis-St. Paul, Minnesota, Spring 2006

This page last updated: 01/09/2013
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 U.S. Geological Survey
Title USGS High Resolution Orthoimagery, Minneapolis-St. Paul, Minnesota, Spring 2006
Abstract This dataset consists of 0.3-meter pixel resolution (approximately 1-foot), natural color orthoimages covering 1/3 of the Minneapolis-St. Paul urban area footprint.

An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map.

[Note: this metadata record was reformatted at the Minnesota Geospatial Information Office from the record provided by USGS - several of the fields were changed to reflect MnGeo's seamless WMS data delivery]
Purpose The data depicts geographic features on the surface of the earth. It was created to provide easily accessible geospatial data which is readily available to enhance the capability of Federal, State, and local emergency responders, as well as plan for homeland security efforts. This data also supports The National Map.

A digital orthoimage is a geometrically accurate photographic record of landscape conditions at the time of the corresponding aerial photography. As such, High Resolution Orthoimagery is useful for a variety of applications, such as environmental monitoring, facility engineering/maintenance, city/county planning, property line review, etc. The digital orthoimage can be used alone or as a raster basemap for corresponding vector line mapping. The detailed focus of High Resolution Orthoimagery provides emergency responders critical information in determining the best evacuation routes, alternative routes and safe access to aid. High Resolution Orthoimagery assists law enforcement personnel in determining the best locations to place surveillance cameras in high-traffic urban areas and popular attractions. The data assists Federal, State and local emergency responders in planning for homeland security efforts. This data also supports The USGS Seamless system.
Time Period of Content Date 04/2006
Currentness Reference Imagery was flown April 17 and 18, 2006.
Progress Complete
Maintenance and Update Frequency Irregular
Spatial Extent of Data Minneapolis and St. Paul, Minnesota (Twin Cities metropolitan area)
Bounding Coordinates -93.77
-92.85
45.38
44.62
Place Keywords Twin Cities metropolitan area, Minneapolis, St. Paul, Saint Paul, MN, Minnesota
Theme Keywords imageryBaseMapsEarthCover, orthophoto, air photo, aerial photo, aerial photography, image map
Theme Keyword Thesaurus ISO 19115 Category
Access Constraints Any downloading and use of these data signifies a user's agreement to comprehension and compliance of the USGS Standard Disclaimer. Insure all portions of metadata are read and clearly understood before using these data in order to protect both user and USGS interests.
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. Acknowledgment of the U.S. Geological Survey would be appreciated for products derived from these data. There is no guarantee of warranty concerning the accuracy of the data. Any user who modifies the data is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data, nor to imply that changes made were approved or endorsed by the U.S. Geological Survey. Please refer to www.usgs.gov/privacy.html for the USGS disclaimer.
Contact Person Information , Customer Services Representative
U.S. Geological Survey
USGS Earth Resources Observation and Science Center
Sioux Falls, SD  57198-0001
Phone: 605-594-6151
Fax: 605-594-6589
Email: webmapping@usgs.gov
Browse Graphic Click to view a data sample
Associated Data Sets For information on other air photos available for Minnesota, see www.mngeo.state.mn.us/chouse/airphoto/index.html

Section 2 Data Quality
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 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. Seamlines mismatches are not corrected unless the overall displacement exceeds one meter. Logical consistency is implicit in the raster image data structure. Source imagery is cloud free.
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. Photography was flown during leaf-off in deciduous vegetation regions. Coastal areas and international boundary regions may have areas without images (void areas) in parts of the coverage. These void areas have a radiometric value of either zero (black) or 128 (uniform gray).
Horizontal Positional Accuracy The design accuracy is estimated not to exceed 3-meter diagonal RMSE (2.12m RMSE in X or Y).

The estimated horizontal positional accuracy value for the dataset is 1.0 meters.

The horizontal positional accuracy and the assurance of that accuracy depend, in part, on the accuracy of the data inputs to the rectification process. The location of existing photoidentifiable ground control and aerotriangulation points were evaluated on the Geotiff image and compared with their ground values in order to determine an overall accuracy for each test block of orthoimages within the project. After image coordinate measurement was completed for each block, an RMSE for the diagonal error was calculated for the orthoimages within the block. This value is an estimate of the horizontal accuracy of the tile expressed in meters.

Citation: Federal Geographic Data Committee, 1998, Geospatial Positioning Accuracy Standard, Part 3, National Standard for Spatial Data Accuracy, FGDC-STD-007.3-1998
Vertical Positional Accuracy There is no vertical accuracy component to orthophotography.
Lineage SOURCES

1. Source Imagery, Originator: Aero-Metric, Inc.

Source imagery for orthorectification process. Source scale denominator: 21600

2. Aerotriangulation, Originator: Aero-Metric, Inc.

Aerotriangulation provides the exterior orientation parameters (X, Y, Z, omega, phi, kappa) for input to the orthorectification process.

3. Minneapolis-St. Paul, MN 10-Meter USGS DEM

Used to provide ground elevations for orthorectification process.


PROCESSING STEPS at Aero-Metric, Inc.

The rectification process requires, as input, a digital elevation model (DEM) gridded to user-specified bounds, a digital image file (PHOTO), and external orientation parameters for the aerial photograph which are typically derived from aerotriangulation (ATCONTROL).

Natural Color imagery was collected at a photo scale of 1:15000 and scanned at 18 microns to generate the raw raster scans. Airborne GPS positions were computed by Photo Science, Inc. and used as control in the aerotriangulation process. The scanned aerial images, ABGPS data, ground check point data, and camera calibration data were used as inputs to the aerotriangulaton process. ISAT 04.05 was used to perform block adjustments and generate exterior orientation parameters for each photo. The external orientation parameters were used to provide the geospatial control each photograph during orthorectification. Vertical control for the orthorectification process was obtained from existing USGS Digitial Elevation Models (DEM). During the orthorectification process, elevation data were extracted and resampled to meet user-specified intervals and bounds.

The orthorectified imagery is resampled to a 0.3-meter ground resolution with a ground extent of 1500 meters by 1500 meters, without overlap. Each 1500-meter orthoimage was generated from a mosaic created from multiple photographs. Orthoproduction was performed using the Intergraph Ortho Pro 4.4.18. Seamlines were Manually Generated and tone balanced between frames prior to cutting out into 1500-meter products. The orthorectified imagery is georeferenced to UTM zone 16, NAD83, meters.

All orthoimages are individually inspected for content, misalignments along mosaic seamlines, and void areas. Source information was collected and verified manually during the production process.

PROCESSING STEPS at EROS Data Center, USGS

In November 2006, this data was resampled to align to the USNG using the USGS Seamless system.

The metadata were imported and updated for display through the Seamless Data Distribution System.


PROCESSING STEPS at MnGeo (formerly LMIC)

USGS delivered the imagery to MnGeo in TIFF format in tiles with no overlap. MnGeo read them directly into a database and serves the images over the web via a WMS server in JPG format.

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
Cell Width 0.3
Cell Height 0.3

Section 5 Attributes
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. Areas where data is incomplete due to lack of full image coverage are represented with the numeric value of 0.
Detailed Citation U.S. Department of the Interior, U.S. Geological Survey, 1999, Standards for Digital Orthoimagery: Reston, VA
Table Detail:

Section 6 Distribution
Publisher USGS and MnGeo
Publication Date 2006
Contact Person Information Nancy Rader, GIS Data Coordinator
Minnesota Geospatial Information Office
658 Cedar Street
St. Paul, MN  55155
Phone: 651-201-2489
Fax: 651-296-3698
Email: clearing.house@state.mn.us
Distributor's Data Set Identifier Twin Cities high resolution DOQs 2006
Distribution Liability 1. USGS Disclaimer:

Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty. Data may have been compiled from various outside sources. Spatial information may not meet National Map Accuracy Standards. This information may be updated without notification. The USGS shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results.

2. MnGeo disclaimer: www.mngeo.state.mn.us/chouse/disclaimer.html
Ordering Instructions 1. MnGeo's Geospatial Image Server

The imagery is available to view via WMS (Web Mapping Service) from MnGeo's Geospatial Image Server. Click on 'Online Linkage' field below to see a webpage that provides the url to connect to the Geospatial Image Server as well as information about how to use WMS services.

2. NorthStar Mapper

View and download imagery from MnGeo's NorthStar Mapper online interactive map at: www.mngeo.state.mn.us/chouse/northstarmapper.html

After you click on "Start Mapping", find these photos as the "USGS Twin Cities Air Photos 2006" layer under "Air Photos and Basemaps"
For help using NorthStar Mapper, see: www.mngeo.state.mn.us/chouse/northstarmapper_help.html

3. EarthExplorer

USGS distributes archived air photos from their EarthExplorer site at: earthexplorer.usgs.gov
Search for Dataset Name: 200604_minneapolis-st_paul_mn_0x3000m_utm_clr under "Additional Criteria".

For help using EarthExplorer, see: earthexplorer.usgs.gov/help/
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 01/09/2013
Contact Person Information Nancy Rader, GIS Data Coordinator
Minnesota Geospatial Information Office
658 Cedar Street
St. Paul, MN  55155
Phone: 651-201-2489
Fax: 651-296-3698
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: 01/09/2013
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