Metadata for Montana 2011 Color NAIP Orthophotos, 24-Kilometer Tiles

Identification Information
Data Quality Information
Spatial Reference Information
Entity and Attribute Information
Distribution Information
Metadata Reference Information

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Identification Information:

Citation:

Originator: Surdex Corporation
Publication date: 2012
Title: Montana 2011 Color NAIP Orthophotos, 24-Kilometer Tiles
Online linkage: http://apps.msl.mt.gov/Geographic_Information/Data/Aerial_Photos/naip_2011_default.aspx

Browse graphic file name: ftp://ftp.geoinfo.msl.mt.gov/Documents/Maps/Individual/20110301_688_NAIP_2011_dates.gif
Browse graphic file description: Map showing aerial photography dates

Abstract:

These data are digital aerial photos of the entire state of Montana, taken in the year 2011. They consist of 715 24x24-kilometer orthorectified natural-color MrSID images (version MG2) with a ground resolution of 1 meter, and they are registered to the Montana State Plane coordinate system, NAD83 High Accuracy Reference Network, units meters.

The data were created for the U.S. Farm Services Agency National Agricultural Imagery Program (http://www.apfo.usda.gov) by Surdex Corporation. A version of the data in Montana State Plane Coordinates was provided to the State Library as a collection of 6022 TIFF images. The State Library mosaiced, compressed, and clipped the data to form the 24-kilometer tiles. Data in TIFF format are available from the Farm Services Agency and by request from the State Library. The TIFF images are 4-band images that include a near-infrared band.

An ESRI shapefile showing the dates the images were collected is available at ftp://ftp.geoinfo.msl.mt.gov/Data/Spatial/MSDI/Imagery/2011_NAIP/24_km_tiles/00_naip_2011_dates.zip and a shapefile showing the extents and names of the 24-kilometer tiles is at ftp://ftp.geoinfo.msl.mt.gov/Data/Spatial/MSDI/Imagery/2011_NAIP/24_km_tiles/00_naip_2011_tile_index.zip.

Purpose:

These aerial photographs were captured to support various governmental, municipal, tribal, and emergency management Geographic Information System activities. Orthorectified aerial photographs can be used to determine the geographic location of objects visible on the photos.

The original imagery was acquired to meet USDA program requirements including conservation planning and soil survey.

Time period of content:

Calendar date: 2011
Currentness reference: Ground Condition

Status:

Maintenance and update frequency:: For information on future updates of the NAIP, see the Aerial Photography Field Office web site.

Access constraints: None

Use constraints:

The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time.

Point of contact:

Montana State Library
P.O. Box 201800
Helena, Montana 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: 406-444-4799
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov

Data Quality Information:

Horizontal Positional Accuracy Report:

Farm Services Agency Digital Orthophoto Specifications. The specified accuracy for 1-meter imagery such as this is 5 meters.

Lineage:

Source information:

Originator: Surdex Corporation
Publication date: 2012
Title: Aerial Photography
Beginning date: 07/15/2011
Ending date: 09/21/2011

Process step:

Cessna Conquest aircraft were used for acquisition of the aerial images. Multiple Intergraph Digital Mapping Camera (DMC) systems where utilized in the data capture. The DMC is a digital frame camera that produces a central perspective image with a nominal focal length of 120mm projecting an image on a virtual CCD measuring 13,824 by 7,680 pixels. The pixels are 12um by 12 um. Images from four panchromatic cameras modules, each with a 120mm lens projecting an image on a 7,168 by 4,096 CCD, are assembled to create the virtual frame. The targeted flight altitude was approximately 30,000 feet above ground level. Images captured simultaneously from four 3,072 by 2,048 pixel multispectral (MS) cameras with 30mm lenses produce red, green, blue and near infrared images. These MS images are matched to the Pan virtual image using the Post Processing Software from Intergraph. All DMC systems used for capture have been calibrated by the manufacturer. The calibration includes measuring the radiometric and geometric properties of each camera. These data are used in the Post Processing Software to eliminate the radiometric and geometric distortion.

The raw captured pixel resolution of the panchromatic virtual frame ranges from 0.60m to 1.04m across the project area depending on terrain height. Each pixel is assigned a 12 bit digital number (DN) by the analog to digital conversion performed after each exposure. Each pixel is resampled during orthorectification to an output resolution of 1m at a bit depth of 8 for each image band. Four bands of data were captured for each image; Blue: 400-580 nm, Green: 500-650 nm, Red: 590-675 nm and Near infrared: 675-850 nm.

All aerial imagery was collected with associated GPS data. When possible most imagery will also include IMU data collection. GPS/IMU data were captured with either an Applanix POS 510 system or IGI AEROControl. The GPS data was utilized to control the aerial triangulation process. All imagery was processed through an aerial triangulation in which the airborne GPS data was constrained to expected limits. Analysis was performed to assure that all image frames fit within a strip and between strips by evaluating the image and airborne GPS residuals. The final adjustments assure a high quality relative adjustment and a high quality absolute adjustment limited to the airborne GPS data accuracy. This process assures the final absolute accuracy of all geopositioned imagery.

Both signalized and photo identified ground control were used to QC and control the IMU/GPS based aerial triangulation bundle block solution. For each project area the latest NED was downloaded from the USGS National Map Seamless Server website in late Spring2011. Thirty Meter NED was used in all cases, and preferred over the available 10 meter spacing to minimize image smearing and distortions that are exacerbated by a finer, but not more accurate DEM. A visual inspection of the NED using color cycled classification by elevation and a shaded relief was performed to check for gaps, corruption and gross errors. When available the NED was compared to known higherquality elevation sources to detect flaws.

Between 20-60 construction points per frame derived from conjugant image measurements performed during aerial triangulation were projected to the NED. The predicted horizontal error for each point was added as an attribute in the SURDEX enterprise database. An operator reviewed ortho seams in areas these predicted errors indicated horizontal error in excess of the contract specifications. Any imagery errors introduced by source NED required patching from an alternate DEM or frame of photography with a different perspective. Hardware used included the DMC, various brands of L1/L2 Survey grade GPS receivers, various brands and models of computers, RAID5 storage, solid state storage, NEC brand calibrated monitors, various brands of monitor calibration colorimeters. Software included Intergraph Post Processing Software (PPS) to handle camera raw images processed to virtual frame panchromatic images and four band multispectral images. SURDEX software was used to color correct and remove bidirectional reflectance, vignetting and other illumination trends.

USDA APFO Image Metrics are measured and images corrected to conform to the Image Metrics using SURDEX software. SURDEX software was then used to fuse the high resolution pan with the lower resolution multispectral image. This image was upsampled to match the pan resolution using bilinear interpolation and converted to a high resolution image via the Brovey Transform. GPS/IMU data was reduced to projected coordinates in the appropriate UTM zone using the Applanix or IGI office software. Aerial Triangulation was performed using Intergraph ImageStation Automatic Triangulation (ISAT), ImageStation Digital Mensuration (ISDM) and Photo-T bundle adjustment. SURDEX software was used to determine the weak points in the AT construction point distribution. SURDEX software was used to orthorectify the images.

SURDEX software was used to compare overlapping orthoimages and correct for minor radiometric variation between adjacent images. SURDEX software was used to calculate the optimal seam path, check seam topology and create master tiles. SURDEX ortho software generates occlusion/smear polygons used during seam review to cut in the best view of steep terrain. SURDEX software was used to visually inspect master tiles for seam and image defects. For Radiometry, SURDEX Grouping Tool was used to display large groups of images, display individual and group histograms, and develop color correction parameters to adjust image DN. Grouping Tool provides real-time updates of the USDA APFO Image Metrics. The image technician adjusts image correction parameters to bring the radiometric characteristics of large groups of raw images within the Image Metrics ranges. Grouping Tool was used again after DOQQ to provide a quality assurance check.

Individual images may not meet the USDA APFO Image Metrics ranges due to land cover. The goal was to have the state as a whole meet the Image Metrics. To validate the accuracy of the block adjustment derived from GPS, IMU, camera parameters and conjugate point measurements photo identifiable ground control points will be surveyed within each State. In Montana 2011, a total of 65 points were utilized. These points will be surveyed by GPS techniques to produce coordinates that are accurate to +/- 0.25 meters RMSE in X,Y,Z. The GPS surveying techniques utilized will assure that the coordinates are derived in the required project datum and relative to an approved National Reference System like OPUS. A report was generated to document the point locations, their description, the final adjusted values and the derived positional accuracy. The field surveying techniques may consist of static OPUS observations, static GPS observations, real time differential GPS observations and VRS observations. The control points were measured on multiple photographs, initially solved as check points and the bundle was rerun including all points as control. After the checkpoint run the residual errors were reviewed to determine the quality of the solution with only GPS and IMU based initial exterior orientation. If the block does not fit the control points within specifications the pass and tie points were reviewed for blunders and weak areas. If, after these corrections were made, the block still does not fit the control well the GPS and IMU processing were reviewed. Once the block has proper statistics and fits the control to specifications the final bundle adjustment was made. SURDEX software was used to predict the horizontal error that results from DEM error using AT construction points projected to the NED ground elevation. As AT points are frequently on man-made and other vertical features not includedin the DEM these ortho points can only be used to indicate regions of error by the clusters of points that predict excessive horizontal displacement. All products are reviewed by independent personnel prior to delivery.

Process contact:

Tim Bohn
Surdex Corporation
520 Spirit of Saint Louis Boulevard
Chesterfield, MO 63005
Telephone: 636-368-4400
E-Mail: TimB@surdex.com

Process step:

A 24x24-kilometer tile system was set up for Montana, and a Python macro was written for the ESRI arcpy module that compared the extent of each tile with the extent of the TIFF images. This macro produces an XML file formatted to be loaded as a project by GeoExpress, a software package produced by Lizard Tech (http://www.lizardtech.com) that manipulates image data and produces MrSID images. The GeoExpress project compresses data from the appropriate TIFF images that cover each tile clips the data to the extent of the tile.


Process date: 02/07/2012

Spatial Reference Information:

Horizontal coordinate system definition:

Grid coordinate system name: State Plane Coordinate System 1983

SPCS zone identifier: 2500

Lambert conformal conic:

Standard parallel: 45
Standard parallel: 49
Longitude of central meridian: -109.5
Latitude of projection origin: 44.25
False easting: 600000.00000
False northing: 0.00000

Planar distance units: meters

Geodetic model:

Horizontal datum name: North American Datum of 1983
Ellipsoid name: Geodetic Reference System 80
Semi-major axis: 6378137
Denominator of flattening ratio: 298.257

Entity and Attribute Information:

Entity and attribute overview:: 24-bit pixels, 3 band color (RGB) represent brightness values 0 - 255

Distribution Information:

Distributor:

Montana State Library
PO Box 201800
Helena, MT 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: 406-444-4799
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov

Resource description: Downloadable Data

Distribution liability:

Standard order process:

Digital form:

Format name: MrSID Generation 2
Online option:

Metadata Reference Information:

Metadata date: 10/28/2013

Metadata review date: 07/19/2013

Metadata review date: 04/17/2013

Metadata review date: 02/07/2011

Metadata contact:

Montana State Library
P.O. Box 201800
Helena, Montana 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: 406-444-4799
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov