U.S. Geological Survey
Unknown
2LPK642430. 2012 Multispectral Color Orthophotography at .30m GSD, UTM z2S projection, GeoTIFF file format for American Samoa.
1.0
Remote-sensing image
Reston, VA
Reston, VA
The 2012 American Samoa aerial photography project produced 1' (.30m) GSD multispectral digital orthoimagery for approximately 85 square miles of the American Samoa islands of Tutuila, Aunu'u, Ofu, Olosega, and Ta'u.
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, thus it combines the image characteristics of a photograph with the geometric qualities of a map.
The digital orthoimagery is both high resolution and spatially accurate, and can serve as a raster base image for mapping
projects as well as a data source to support the derivation of new raster and vector data sets.
Digital aerial imagery was obtained in August 2012 using a large format Microsoft Vexcel Ultracam,
equipped with Airborne GPS/IMU. A total of three areas consisting of 26 flight lines with 671 frames were acquired under a single task order, in multispectral
(RGB and NIR) 8 bits per band format. The imagery was acquired with a 100.5 mm focal length at an altitude of 9,000' above
mean terrain, to yield a raw pixel resolution of 1' (.30m) suitable for photogrammetric mapping and orthophoto production. The 'leaf condition' was not a concern
but imagery was collected in the summer of 2012 under conditions free from flooding and excessive soil moisture. Within populated areas, no more than 5% clouds,
cloud shadows, smoke, and haze are permitted. In the uninhabited areas of the islands 10% of clouds, cloud shadows, smoke, and haze may exist. There is no tide coordination.
The sun angle threshold was 30 degrees. The imagery consisted of panchromatic, blue, green, red and near infrared bands.
The three color bands and near infrared bands were pan sharpened and archived as frame imagery. All 4 bands were used in the orthophoto production.
The two mission baseline information are as follows: August 2, 2012 minimum baseline length is 0.476km; maximum baseline length is 32.432km; and mean baseline length is 12.358km. August 3, 2012 minimum baseline length is 0.022km; maximum baseline length is 40.399km; and mean baseline length is 14.860km.
20120803
Ground condition
Unknown
-169.6841203
-169.6701437
-14.1841442
-14.1977801
None
rectified photograph
rectified image
orthophoto
natural color orthophoto
orthoimage
image map
U.S. Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions (Federal Information Processing Standard (FIPS) 10-4): Washington, D.C., National Institute of Standards and Technology.
US
U.S. Department of Commerce, 1987, Codes for the Identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard (FIPS) 5-2): Washington, D.C., National Institute of Standards and Technology.
AS
None
American Samoa
Tutuila
Aunu'u
Ofu
Olosega
Ta'u
None
The United States Geological Survey shall not be held liable for any errors in this data. This includes errors of omission, errors of commission, content errors, and relative and positional accuracy errors in the data. This data should not be construed to be a legal document. Primary sources from which this data was compiled must be consulted for verification of information contained in this data. This data is in the public domain, and may not be resold.
Mike Duncan
United States Geological Survey
mailing and physical
1400 Independence Road
Rolla
MO
65401
U.S.
573-308-3579
573-308-3810
e-mail: jduncan@usgs.gov
0800-1700 M-F EST
Email is preferred.
Orthophotos were produced for USGS by Photo Science under the USGS Geospatial Production and Services Contract, Contract Number G10PC00026, Task Order G12PD00480.
Radiometry was verified by visual inspection of the digital orthophotos. 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 was performed over a group of images during the mosaicking process in order to lighten or darken adjacent images for better color tone matching.
All GeoTIFF tagged data and image file sizes were validated using commercial GIS software to ensure proper loading before being archived. This validation procedure ensured correct physical format and field values for tagged elements. Seam lines and tile edges were visually inspected.
The 'leaf condition' was not a concern
but imagery was collected in the summer of 2012 under conditions free from flooding and excessive soil moisture. Within populated areas, no more than 5% clouds,
cloud shadows, smoke, and haze are permitted. In the uninhabited areas of the islands 10% of clouds, cloud shadows, smoke, and haze may exist. There is no tide coordination. The sun angle threshold was 30 degrees. To ensure complete coverage, photography was collected for all
tiles that intersected the islands of American Samoa (Tutuila, Aunnu'u, Ofu, Olosega, and Ta'u). Orthoimages were visually inspected for completeness to ensure
that no gaps or image misplacements exist within and between adjacent images.
This 0.30m Ground Sample Distance (GSD) digital ortho imagery was compiled to meet a 1.52 meter (5') horizontal accuracy at 95% confidence level(0.88-meters Root Mean Squared (RMSE) Error XY (0.62 meter RMSE X or Y) based on NSSDA testing guidelines. This accuracy requirement is not applicable in areas where the ground is obscured on the aerial imagery by foliage, prevalent smoke, or dense shadow.
0.709
RMSE at CE95 in meters. Please see Accuracy Analyst report.
There is no vertical component for orthophotos.
Photo Science
Unpublished material
Raw Aerial Imagery
1.0
Remote-sensing image
None
None
External Hard Drive
20120828
Ground condition
IMG1
The digital aerial imagery was obtained using a large format Microsoft Vexcel Ultracam. Aerial imagery was supplemented with the simultaneous acquisition of airborne GPS/IMU data, which captured the ground coordinate for the nadir point of each photograph. Aerial imagery was exposed at an altitude of 9,000' above mean terrain yielding an approximate GSD of 1 foot. A minimum of 70% forward gain and 40% sidelap was collected to ensure full stereo coverage. The aerial images are used in the production of orthophotos.
Photo Science
Unpublished material
Georeferenced Aerial Imagery
1.0
Remote-sensing image
None
None
External Hard Drive
2012
Ground condition
CONT
Targeted ground control was collected for use in the Aerotriangulation process. Sixty-five (65) photo identifiable ground control points were selected and surveyed to adequately cover the entire state. Details of each point can be found in the full control report.
Photo Science
Unknown
LiDAR_DEM
1.0
Vector digital data
None
None
External
2012
Ground condition
LiDAR_DEM
Photo Science developed classified, bare earth, .LAS LiDAR data at a 1-meter nominal post spacing with a fundamental 15 cm vertical accuracy at 95% confidence interval. Some areas of Ta'u were missing LiDAR so a stereocompiled DEM was created from the imagery.
Photo Science
Unknown
Exterior Orientation File
1.0
ASCII Text File
None
None
disc
2012
Ground condition
EOFILE
Exterior Orientation (EO) Parameters (x,y,z,omega,phi,kappa) were produced to provide precise photocenter locations for each frame of imagery. The two mission baseline information are as follows: August 2, 2012 minimum baseline length is 0.476km; maximum baseline length is 32.432km; and mean baseline length is 12.358km. August 3, 2012 minimum baseline length is 0.022km; maximum baseline length is 40.399km; and mean baseline length is 14.860km. Aerotriangulation was necessary to achieve the accuracy requirements of the project.
Photo Science
Unknown
SoftCopy Aerotriangulation
1.0
ASCII Report File
None
None
disc
2012
Ground condition
ATSOL
SoftCopy Aerotriangulation is a computer process of densifying the ground control network from locations in a few of the digital images to numerous points in each digital image that is to be used in the mapping process. This process is dependent on the location and coordinate positions of the ABGPS and GPS photo control points as well as a precise camera calibration for the Microsoft Vexcel Ultracam camera used to capture the images.
Photo Science
Unknown
Tile definition
1.0
Vector digital data
none
none
disc
2012
Ground condition
TLDEF
The tile definition was used to cut orthorectified imagery into manageable, usable images in UTM projection. The UTM deliverables defined by this tile definition were modeled after the U.S. National Grid and references NAD83 UTM projection, units of Meters. Each tile is 1500 X 1500 meters.
Photo Science
Unpublished material
Stereo Imagery
1.0
Remote-sensing image
None
None
External Hard Drive
2012
Ground condition
StereoIMG
The stereoimages are the product of the processed stereo imagery frames and the Aerotriangulation solution. Digital imagery was produced in TIF file format, 4-band, 8-bit stereo pairs.
Photo Science
Unpublished material
Orthorectified Image
1.0
Remote-sensing image
None
None
disc, DVD or online
2012
Ground condition
OIMG
Orthorectified images were geometrically corrected to achieve a uniform scale. Each frame was adjusted for topographic relief, lens distortion and camera tilt.
Photo Science
Unpublished material
Tiled Orthophoto
1.0
Remote-sensing image
None
None
disc, DVD or online
2012
Ground condition
OIMGTILE
The tiled orthophoto was the result of mosaicking orthorectified imagery and using the tile definition to cut the data into manageable, usable orthophotos. 173 ortho tiles for delivery to USGS were created.
Sixty-five (65) photo identifiable control locations were selected and surveyed to adequately cover the entire state. Details of each point can be found in the full control report. Accuracies of 10cm or better (horizontally and vertically) were required.
None
2012
CONT
New digital aerial imagery was obtained in the spring of 2012 using a large format Microsoft Vexcel Ultracam equipped with Airborne GPS/IMU. A total of 22 flight lines with 671 frames were collected in multispectral (RGB and NIR) 12 bits per band format. The imagery was acquired with a 100.5 mm focal length at an altitude of 9,000' above mean terrain, to yield a raw pixel resolution of 1' (.30 m) suitable for photogrammetric mapping and orthophoto production. The 'leaf condition' was not a concern but imagery was collected in the summer of 2012 under conditions free from flooding and excessive soil moisture. Within populated areas, no more than 5% clouds, cloud shadows, smoke, and haze are permitted. In the uninhabited areas of the islands 10% of clouds, cloud shadows, smoke, and haze may exist. There is no tide coordination. The sun angle threshold was 30 degrees. To ensure complete coverage, photography was collected for all tiles that intersected the islands of American Samoa (Tutuila, Aunnu'u, Ofu, Olosega, and Ta'u). Orthoimages were visually inspected for completeness to ensure that no gaps or image misplacements exist within and between adjacent images.
None
2012
IMG1
Imagery and AGPS/IMU data is downloaded from the hard drive on the plane to the hard drive on the ground. AGPS/IMU mission data is processed together with continuously collected ground-based CORS GPS base station data in forward and reverse directions. This precisely determines the aerial camera's position and orientation in the terrain (project) coordinate system and allows for correct orientation of the imagery.
None
2012
EOFILE
The EOFILE, raw frames, and control points were input into ISAT in order to complete the SoftCopy Aerotriangulation, described in ATSOL source contribution, and assembled into a block. A second degree block adjustment is run along with the full least squares bundle adjustment. Once the last set of blunders and adjustments are complete, a final block bundle adjustment is run to produce the final solution. The final adjustment of the block is accomplished by using a rigorous simultaneous least squares bundle adjustment. The general procedure is to remove all blunders from the data using automatic blunder detection. The bundle adjustment is then run with minimal ground control to test the photogrammetric measurements for consistency. Next, the full ground control data set, including ABGPS data, is added to the adjustment. The horizontal control is then tightened and the effect on the vertical control and the photogrammetric residuals are inspected. The final adjustment makes sure that all of the measurements are in balance with each other and properly represent the actual conditions.
IMG1
ATSOL
CONT
2012
StereoIMG
The rectification process required as input a digital elevation model (LiDAR_DEM), imagery (IMG1) and soft copy aerotriangulation solution (ATSOL). The orthorectified imagery was produced using Intergraph Orthopro software. It used ImageStation Photogrammetric Manager (ISPM) for photogrammetry project setup, file management, and importing triangulation data from a user defined ASCII file (ATSOL). The ortho project records all the operations, including all the parameters that are defined through the OrthoPro workflow, such as the project area coordinates, pixel size, rotation angle, ISPM project and its unorthorectified source images, product areas (TLDEF) orthorectification settings, seamlines and so on. The results are single frame images that have yet to be mosaicked into manageable tiled orthos. The single frame orthos were checked for accuracy against the surveyed ground control before further image editing.
IMG1, LiDAR_DEM, ATSOL
2012
OIMG1
Orthorectified imagery was mosaicked, locally color-balanced and cut to the tile definition boundaries (TLDEF) using Intergraph Orthopro software. Tiled orthophotos then went through a rigorous manual QC process to evaluate for remaining hotspots (sun reflectance over water), tone quality, color balance and the feathering area along seamlines. Any imperfections at this point were manually edited. Clouds and cloud shadows were attempted to be minimized by using alternate views from adjoining frames. The tiled images were then converted to the required file format (GeoTIFF) and transferred to external hard drives for delivery to USGS.
OIMG1, TLDEF
2012
OIMGTILE
Raster
Pixel
1500
1500
0.300000
0.300000
8
4
GCS_North_American_1983
NAD_1983_HARN_UTM_Zone_2S
coordinate pair
meters
0.30
0.30
Universal Transverse Mercator
2
0.999600
-171.00000000
0.000000
500000.000000
10000000.00000000
North American Datum of 1983 HARN
Geodetic Reference System 80
6378137.000000
298.257222101000020000
These digital orthophotos are composed of 4 bands or channels of information. Each band comprises a grid of pixels containing digital numbers ranging from 0-255, and representing colors in the red, green, blue (RGB) or near infrared (NIR) portions of the electromagnetic spectrum.
None
20121121
Mike Duncan
United States Geological Survey
mailing and physical
1400 Independence Road
Rolla
MO
65401
U.S.
573-308-3579
573-308-3810
e-mail: jduncan@usgs.gov
0800-1700 M-F EST
Email is preferred.
FGDC CSDGM
FGDC-STD-001-1998