| Section 1 | Overview | |||
| Originator | National Geospatial-Intelligence Agency (NGA), U.S. Geological Survey (USGS) | |||
| Title | USGS High Resolution Orthoimagery, Minneapolis - St. Paul, MN, Spring, 2004 | |||
| Abstract | This dataset consists of 0.3-meter pixel resolution (approximately 1-foot), natural color orthoimages covering 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 web mapping service (WMS) data delivery] | |||
| Purpose | These data have been created as a result of the need for having geospatial data immediately available and easily accessible in order to enhance the capability of Federal, State, and local emergency responders, as well as plan for homeland security efforts.
Data_Set_Credit: This dataset was created in support of the National Geospatial-Intelligence Agency (NGA) and the USGS. The data will support NGA's Homeland Security mission and The National Map of the USGS. The following companies produced the data to support this task - 3001, Inc. EarthData International of Maryland, LLC | |||
| Time Period of Content Date | 04/24/2004 | |||
| Currentness Reference | 2004 | |||
| Progress | Complete | |||
| Maintenance and Update Frequency | Irregular | |||
| Spatial Extent of Data | Minneapolis and St. Paul, Minnesota (Twin Cities metropolitan area) | |||
| Bounding Coordinates | -93.52 -92.75 45.26 44.74 | |||
| Place Keywords | Minnesota, MN, Twin Cities metropolitan area, Minneapolis, St. Paul, Saint Paul | |||
| Theme Keywords | imageryBaseMapsEarthCover, orthophoto, air photo, aerial photo, aerial photography, image map | |||
| Theme Keyword Thesaurus | ISO 19115 Topic 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. Acknowledgment of the National Geospatial-Intelligence Agency (NGA) and the U.S. Geological Survey (USGS) would be appreciated for products derived from these data. | |||
| Contact Person Information | Customer Services,
U.S. Geological Survey EROS Data Center, 47914 252nd Street Sioux Falls, SD 57198-0001 Phone: 800-252-4547 Fax: 6055946589 Email: custserv@usgs.gov | |||
| Browse Graphic | None available | |||
| Associated Data Sets | For information on other air photos available for Minnesota, see https://www.mngeo.state.mn.us/chouse/airphoto/index.html | |||
| Section 2 | Data Quality | |||
| Attribute Accuracy | The digital imagery for each acquisition sortie is differentially rectified to produce orthophotography for the Red, Green, and Blue channels at a resolution of 0.3-meter per pixel. As a part of the ISTAR workflow, the data from the color channels is edge sharpened using the nadir panchromatic channel. The orthophoto mosaics are inspected for accuracy issues that fall in the following categories: Aerotriangulation related digital surface model (DSM) related Accuracy issues will be investigated through review and correction of the DSM or triangulation adjustment. Once the imagery has passed quality control review, final radiometric adjustments are performed to create a uniform overall appearance. | |||
| Logical Consistency | ||||
| Completeness | ||||
| Horizontal Positional Accuracy | Horizontal_Positional_Accuracy_Report:
Compliance with the accuracy standard was ensured by the placement of photo identifiable ground control points and the collection of airborne GPS data. Using several tools that are part of the ISTAR workflow, a digital surface model (DSM) was correlated at a post spacing of 2 meter depending on terrain and land cover. The ISTAR correlation algorithm computes the X,Y,Z value for each DSM post utilizing every stereo angle that is available. A series of DSM files were created for each acquisition block, one for each stereo look angle. A mosaic was then created from the separate DSM files where the best vertical value for each posting was selected from all look angles compared against the aerotriangulation adjustment which is incorporated into the mosaic. EarthData will then edit the surface to the level required to support the orthophoto production. A root mean square (RMS) value was calculated based on the imagery utilized in the production of the tile by comparing the AT X and Y coordinates. This value represents an estimate of the accuracy of the horizontal coordinate measurements in the tile expressed in meters. The design accuracy is estimated not to exceed 3-meter diagonal RMS error (2.12m RMSE in X or Y). Horizontal_Positional_Accuracy_Value: 0.121371 Horizontal_Positional_Accuracy_Explanation: The horizontal accuracy of the orthorectified images is mainly determined by the accuracy of the aerotriangulation and digital surface model (DSM). For each rectified image (lift), an RMSE value for all of the standard errors of the tie/pass/control points located in that image (lift) and computed by the aerotriangulation solution was calculated. The DSM accuracy assessment was achieved by comparing the aerotriangulation-derived elevation with the elevation of the DSM. In addition, visual examination was employed to assess all tiles and its relative edge match. All results were examined for consistency and its compliance with the NSSDA accuracy standard. | |||
| Vertical Positional Accuracy | N/A | |||
| Lineage | USGS Processing Steps:
SOURCES 1. MN11504A Source_Contribution: Digital source imagery for tile production Originator: EarthData International of Maryland, LLC Calendar_Date: 04/24/2004 (ground condition) Source_Scale_Denominator: 50000 Type_of_Source_Media: Digital Source_Citation_Abbreviation: Imagery 2. Minneapolis - St. Paul, MN Digital Surface Model Source_Contribution: Used to provide ground elevations for the orthorectification process Originator: EarthData International of Maryland, LLC Calendar_Date: 07/06/2004 (ground condition) Type_of_Source_Media: Digital Source_Citation_Abbreviation: DSM 3. Ground Control Survey of Minneapolis-St. Paul, MN Source_Contribution: The control provides a means for referencing the project source imagery to a geodetic reference frame. Originator: 3001 Inc. Calendar_Date: 20040416 (ground condition) Type_of_Source_Media: Digital Source_Citation_Abbreviation: GPS ground control PROCESS DESCRIPTION Process_Date: 07/23/2004 Source imagery: ADS40 Digital Camera Imagery. Control: Airborne GPS/IMU supplemented with photo identifiable field control. Aerotriangulation: ISTAR software package. Elevation Model: ISTAR software package. Radiometric Balancing: ISTAR software package and COTS Software (PhotoShop). Orthorectification: ISTAR software package. Mosaic: ISTAR software package and Z/I Imaging OrthoPro software package. The following section describes the ISTAR digital image production sequence. This is a mature, stable workflow and incorporates all production components into an integrated series of tools to accomplish photogrammetric mensuration, aerotriangulation, elevation model development, ortho production and finishing. Production processes are fully documented in accordance with ISO9001 mandates. The following is a step-by-step description of the ISTAR production workflow used to develop digital orthophotography to support the Minneapolis-St. Paul, MN task: 1. The unprocessed ADS40 data and accompanying GPS and IMU data for one or more sorties is downloaded from the portable hard disks and checked to verify that no files are corrupted and that all data can be downloaded. 2. The GPS/IMU (internal measure unit) parameters for each sortie are optimized using the ground control points and the error calibration map. The horizontal and vertical positions of all ground control points in the block are observed in each channel (R,G,B, IR, S1 Pan ,S2 Pan and Nadir Pan). 3. Aerotriangulation is accomplished using the CLB tool that is a component of the ISTAR process. The ground control, GPS and IMU information is ingested and tie points between strips are identified. Normally, only three (3) tie points are needed between adjacent flight lines. 4. CLB produces a bundle adjustment for each data sortie. A digital file containing the RMSE computations of the adjustment is derived and available as a deliverable. The results of the adjustment are verified through the development of a sub-sampled panchromatic mosaic for the data sortie. The mosaic is corrected using the aerotriangulation points only. This mosaic is inspected by the photogrammetric technician to identify any gross errors in the adjustment as well as the identification of any voids or image quality problems. 5. Using several tools that are part of the ISTAR workflow, a digital surface model (DSM) is correlated at a post spacing of 2 meter depending on terrain and land cover. The ISTAR correlation algorithm computes the X,Y,Z value for each DSM post utilizing every stereo angle that is available. A series of DSM files are created for acquisition block, one for each stereo look angle. A mosaic is then created from the separate DSM files where the best vertical value for each posting is selected from all look angles compared against the aerotriangulation adjustment which is incorporated into the mosaic. EarthData will then edit the surface to the level required to support the orthophoto production. 6. The digital imagery for each acquisition sortie is differentially rectified to produce orthophotography for the Red, Green, and Blue channels at a resolution of 0.3-meter per pixel. As a part of the ISTAR workflow, the data from the color channels is edge sharpened using the nadir panchromatic channel. The orthophoto mosaics are inspected for accuracy issues that fall in the following categories: Aerotriangulation related DSM related Accuracy issues will be investigated through review and correction of the DSM or triangulation adjustment. Once the imagery has passed quality control review, final radiometric adjustments are performed to create a uniform overall appearance. The final 1500-meter X 1500-meter tiles are clipped out and the imagery is output in GeoTIFF format. GeoTIFF files will include the following GeoTIFF tags and keys: Model Tiepoint Tag Model Pixel Scale Tag GT Model Type Geo Key GT Raster Type Geo Key Projected CST Type Geo Key PCS Citation Geo Key Proj Linear Units Geo Key 7. The completed digital orthophotos are checked for image quality. Minor artifacts will be corrected using Adobe Photoshop in an interactive editing session. Digital files are assigned final names derived from the southwest corner of each tile and are based on the U.S. National Grid (USNG). 8. The project manager is responsible for coordinating and performing quality control on the Federal Geographic Data Committee (FGDC) compliant metadata. File level metadata is provided in .xml format. Land Management Information Center (LMIC) Processing Steps: USGS delivered the imagery to LMIC (now MnGeo) in TIF format in almost 800 tiles with no overlap. LMIC staff 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 | The digital imagery for each acquisition is differentially rectified to produce orthophotography for the Red, Green, and Blue channels at a resolution of 0.3-meter per pixel. | |||
| Detailed Citation | ||||
| Table Detail: | ||||
| Section 6 | Distribution | |||
| Publisher | Minnesota Geospatial Information Office (MnGeo) | |||
| Publication Date | 2004 | |||
| Contact Person Information | MnGeo, GIS Specialist
Minnesota Geospatial Information Office (MnGeo) 658 Cedar Street St. Paul, MN 55155 Phone: 651-201-2499 Email: gisinfo.mngeo@state.mn.us | |||
| Distributor's Data Set Identifier | doq_msp04, Twin Cities high resolution DOQs 2004 | |||
| 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's data disclaimer is online: https://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: https://www.mngeo.state.mn.us/chouse/northstarmapper.html After you click on "Start Mapping", find these photos as the "USGS/NGA Twin Cities Air Photos 2004" layer under "Air Photos and Basemaps" For help using NorthStar Mapper, see: https://www.mngeo.state.mn.us/chouse/northstarmapper_help.html 3. EarthExplorer USGS distributes archived air photos from their EarthExplorer site at: http://earthexplorer.usgs.gov/ For help using EarthExplorer, see: http://earthexplorer.usgs.gov/help/ | |||
| Online Linkage | I AGREE to the notice in "Distribution Liability" above. Clicking to agree will either begin the download process, link to a service, or provide more instructions. See "Ordering Instructions" above for details. | |||
| Section 7 | Metadata Reference | |||
| Metadata Date | 01/08/2015 | |||
| Contact Person Information | MnGeo, GIS Specialist
Minnesota Geospatial Information Office (MnGeo) 658 Cedar Street St. Paul, MN 55155 Phone: 651-201-2499 Email: gisinfo.mngeo@state.mn.us | |||
| Metadata Standard Name | Minnesota Geographic Metadata Guidelines | |||
| Metadata Standard Version | 1.2 | |||
| Metadata Standard Online Linkage | https://www.mngeo.state.mn.us/committee/standards/mgmg/metadata.htm | |||