| Section 1 | Overview | |||
| Originator | Dakota County, Minnesota | |||
| Title | High Resolution Orthoimagery, Dakota County, MN, Spring 2013 | |||
| Abstract | This dataset consists of 0.15-meter (approximately 0.5-foot), natural color and false color infrared orthoimages covering Dakota County. Data were collected by Aerometric (now Quantum Spatial). | |||
| Purpose | The purpose of this project was to collect high resolution, orthorectified images of Dakota County. | |||
| Time Period of Content Date | 2013 | |||
| Currentness Reference | The photography was exposed on 4/29/13, 5/12/2013, 5/14/2013, 5/16/13 and 5/23/13. | |||
| Progress | Complete | |||
| Maintenance and Update Frequency | Irregular | |||
| Spatial Extent of Data | Dakota County | |||
| Bounding Coordinates | -93.33 -92.73 44.93 44.47 | |||
| Place Keywords | Minnesota, MN, Dakota County | |||
| Theme Keywords | imageryBaseMapsEarthCover, rectified photograph, rectified image, orthophoto, orthoimage, DOQ, digital orthophoto, aerial photograph, rectified image, county orthophoto | |||
| Theme Keyword Thesaurus | ISO 19115 Category | |||
| 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be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions.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 | Randy Knippel,
GIS Manager Dakota County 14955 Galaxie Ave. Apple Valley, MN 55124 Phone: 952-891-7080 Fax: 952-891-7031 Email: randy.knippel@co.dakota.mn.us | |||
| 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 | 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 Dakota County for this contract. | |||
| 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 | Orthophotos meet or exceed the standard for horizontal (X,Y) position as Root Mean Square Error = Flying Height (5000 ft) / 10,000 = 0.56 feet, with a maximum horizontal deviation of (3 x RMSE) or +/- 1.5 feet. | |||
| Lineage | Source Material
1. Minnesota LiDAR data - Used to provide ground elevations for orthorectification process. More information on the data can be found at: https://www.mngeo.state.mn.us/chouse/metadata/lidar_metro2011.html 2. Aerotriangulation Data - Used to provide photo exterior orientations for orthorectification process. Process Steps - Performed by Aerometric (now Quantum Spatial) The imagery for this project was flown at a nominal acquisition altitude (AGL) of 4,800 feet. Differential baseline lengths were kept to a minimum by the use of the nearest available CORS (Continuously Operating Reference Station) 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. Digital camera(s) were calibrated by the manufacture and the camera parameters refined through in-situ proprietary procedures. The Zeiss DMC (Digital Mapping Camera) images were aero-triangulated to support digital ortho image production for the Dakota County, MN project area. Ground check point data was provided by Dakota County. The project was referenced to the North American Datum of 1983 (HARN), UTM Zone 15 North projection horizontally and to the North American Vertical Datum of 1988 (NAVD88) vertically. Units were in meters. The images, ABGPS/IMU data, and ground check point data were used as inputs to the INPHO Match-AT softcopy program. Match-AT correlated image points and aerotriangulated the block of images to create exposure station exterior orientations. All ground points were manually measured on the imagery. These points were included in the aerotriangulation adjustments for absolute ground location verification. The scale of the aerial photos was 1"=1016'. Rectification was done in INPHO OrthoMaster using the aerotriangulation data, raw images, and existing LiDAR DEM data which was reviewed and edited by AeroMetric. These rectified images were used to automatically generate seamlines which were then fully reviewed and edited. The rectified images were mosaicked, balanced, and cut into final image tiles. The final tiles were reviewed 100% and artifacts were removed as well as other edits performed. MrSID compressed image mosaic was also generated (MG3,50:1 compression) for delivery. 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. Other software that was used includes - INPHO OrthoMASTER 5.5, INPHO Match-T 5.5, IRAS C ver 10.0, Photoshop ver CS5, Windows XP and Windows 7, INPHO OrthoVista 5.5, Global Mapper 13, Bentley MicroStation 8 | |||
| 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 | 0.15 | |||
| Cell Height | 0.15 | |||
| Section 5 | Attributes | |||
| Overview | Natural color orthoimagery is organized in four color bands or channels which represent the red, green, blue and grey (CIR) 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. | |||
| Detailed Citation | ||||
| Table Detail: | ||||
| Section 6 | Distribution | |||
| Publisher | Minnesota Geospatial Information Office (MnGeo) | |||
| Publication Date | 2013 | |||
| Contact Person Information | Nancy Rader,
GIS Data Coordinator Minnesota Geospatial Information Office (MnGeo) 658 Cedar Street St. Paul, MN 55155 Phone: 651-201-2489 Email: gisinfo.mngeo@state.mn.us | |||
| Distributor's Data Set Identifier | doq_dakota13 | |||
| Distribution Liability | MnGeo's data disclaimer is online: https://www.mngeo.state.mn.us/chouse/disclaimer.html
| |||
| Ordering Instructions | The imagery is available to view via WMS (Web Mapping Service) from MnGeo's Geospatial Image Server. The Minnesota Geospatial Image Service web pages provide the url to connect to the Geospatial Image Server as well as information about how to use WMS services. Due to file size there is currently no option to download the photos.
Access via the Minnesota Geospatial Commons by clicking on the 'Online Linkage" field below. | |||
| 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 | 03/19/2015 | |||
| Contact Person Information | Nancy Rader,
GIS Data Coordinator Minnesota Geospatial Information Office (MnGeo) 658 Cedar Street St. Paul, MN 55155 Phone: 651-201-2489 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 | |||