Orthorectified Photomosaic FAQ Metadata
Frequently-anticipated questions:
- Title: Sunset Crater Volcano National Monument Vegetation Mapping Project - Orthorectified Photomosaic
- Abstract:
-
Orthophotos combine the image characteristics of a
photograph with the geometric qualities of a map. The
primary digital orthophotoquad (DOQ) is a 1-meter ground
resolution, quarter-quadrangle (3.75-minutes of latitude by
3.75-minutes of longitude) image cast on the Universal
Transverse Mercator Projection (UTM) on the North American
Datum of 1983 (NAD83).The geographic extent of the DOQ is
equivalent to a quarter-quad plus The overedge ranges a
minimum of 50 meters to a maximum of 300 meters beyond the
extremes of the primary and secondary corner points. The
overedge is included to facilitate tonal matching for
mosaicking and for the placement of the NAD83 and secondary
datum corner ticks. The normal orientation of data is by
lines (rows) and samples (columns). Each line contains a
series of pixels ordered from west to east with the order of
the lines from north to south. The standard, archived
digital orthophoto is formatted as four ASCII header
records, followed by a series of 8-bit binary image data
records. The radiometric image brightness values are stored
as 256 gray levels ranging from 0 to 255. The metadata
provided in the digital orthophoto contain a wide range of
descriptive information including format source information,
production instrumentation and dates, and data to assist
with displaying and georeferencing the image. The standard
distribution format of DOQs will be JPEG compressed images
on CD-ROM by counties or special regions. The reconstituted
image from the CD-ROM will exhibit some radiometric
differences when compared to its uncompressed original but
will retain the geometry of the uncompressed DOQ.
Uncompressed DOQs are distributed on tape.
- How should this data set be cited?
U.S. Geological Survey, 2004, DOQQ Basemap: Sunset Crater Volcano National Monument: U.S. Geological Survey, Reston, VA.
Online Links:
This is part of the following larger work.
M. Hansen, J. Coles, K.A. Thomas, D. Cogan, M. Reid, J. Von Loh, K. Schultz, 2004., USGS-NPS National Vegetation Mapping Program: Walnut Canyon National Monument, Arizona, Vegetation Classification and Distribution, Final Project Report.
- What geographic area does the data set cover?
- West_Bounding_Coordinate: -124.7333
- East_Bounding_Coordinate: -067.9500
- North_Bounding_Coordinate: 49.3833
- South_Bounding_Coordinate: 24.5333
- Description_of_Geographic_Extent: Sunset Crater Volcano National Monument and the environs.
- What does it look like?
- Does the data set describe conditions during a particular time period?
- Beginning_Date: 22-Feb-1994
- Ending_Date: present
- Currentness_Reference: ground condition
- What is the general form of this data set?
- Geospatial_Data_Presentation_Form: remote-sensing image
- How does the data set represent geographic features?
- How are geographic features stored in the data set?
This is a Raster data set.
It contains the following raster data types:
- Dimensions 28442 x 23513 x 1, type Pixel
- What coordinate system is used to represent geographic features?
- Grid_Coordinate_System_Name: Universal Transverse Mercator
- Universal_Transverse_Mercator:
-
- UTM_Zone_Number: 10-19
- Transverse_Mercator:
-
- Scale_Factor_at_Central_Meridian: .09996
- Longitude_of_Central_Meridian: -123 00 00
- Latitude_of_Projection_Origin: 0.0
- False_Easting: 500000.
- False_Northing: 0.0
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 1.000000
Ordinates (y-coordinates) are specified to the nearest 1.000000
Planar coordinates are specified in meters
The horizontal datum used is North American Datum 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257.
- How does the data set describe geographic features?
- Band_1
- Raster
(Source: ESRI)
- ObjectID
- Internal feature number.
(Source: ESRI)
Sequential unique whole numbers that are automatically generated.
- Value
- Panchromatic 8-bit gray-scale value. A value of 0 represents the color black and the value 255 represents the color white. All values between 0 and 255 are represented as a shade of gray varying from black to white.
(Source: U.S. Department of the Interior, U.S. Geological Survey, Standards for digital orthophotos: Reston, VA (<http://rockyweb.cr.usgs.gov/nmpstds/doqstds.html>))
None.
- Count
- The number of pixels that represent each of the unique 0 to 255 color values.
(Source: U.S. Department of the Interior, U.S. Geological Survey, Standards for digital orthophotos: Reston, VA (<http://rockyweb.cr.usgs.gov/nmpstds/doqstds.html>))
Unique counted number.
- Entity_and_Attribute_Overview:
-
For DOQ's from panchromatic source each pixel contains an
8-bit gray-scale value between 0-255. A value of 0
represents the color black while a value of 255 represents
the color white. All values between 0 and 255 are repesented
as a shade of gray varying from black to white. For
color-infrared and natural color DOQs' a digital number from
0 to 255 will also be asssigned to each pixel but that
number will refer to a color look-up table which will
contain the RGB red, blue and green (RGB) values, each from
0 to 255, for that digital number. Areas where the
rectification process is incomplete due to incomplete data
(i.e., lack of elevation data, gaps), are represented with
the numeric value of 0.
- Entity_and_Attribute_Detail_Citation:
-
U.S. Department of the Interior, U.S. Geological Survey,
guide for digital orthophotos: Reston, VA.
A pdf version is available at: URL:
<http://rockyweb.cr.usgs.gov/nmpstds/doqstds.html>
U.S. Department of the Interior, U.S. Geological Survey,
1992, Standards for digital orthophotos: Reston, VA.
- Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
- Who also contributed to the data set?
- To whom should users address questions about the data?
Dan Cogan and Kathryn Thomas
USBR Remote Sensing and GIS Group and USGS Southwest Biological Science Center Colorado Plateau Research Station
Cogan: Physical Scientist; Thomas: PhD Ecologist
Cogan: POB 25007 Bldg 56 D-8260 Denver Federal Center Denver, CO 80225; Thomas: USGS Southwest Biological Science Center Colorado Plateau Research Station P.O. Box 5614 Flagstaff, Arizona 86011
Denver, CO 80225
USA
Cogan: 303-445-2291; Thomas: 928-556-7327 (voice)
303-445-6337 (FAX)
dcogan@do.usbr.gov; kathryn_a_thomas@usgs.gov
- Hours_of_Service: 8:00 - 5:00 MST
- Contact_Instructions:
-
For GIS questions contact Cogan, for ecological questions contact Thomas
DOQ's serve a variety of purposes, from interim maps to
field references for earth science investigations and
analysis. The DOQ is useful as a layer of a geographic
information system and as a tool for revision of digital
line graphs and topographic maps.
- From what previous works were the data drawn?
- DEM1 (source 1 of 4)
-
U.S. Geological Survey, Unknown, digital elevation model: U.S. Geological Survey, Reston, VA.
- Type_of_Source_Media: cartridge tape
- Source_Scale_Denominator: Unknown
- Source_Contribution:
-
Elevation data in the form of an ortho-DEM regridded to
user-specified intervals and bounds.
- PHOTO1 (source 2 of 4)
-
U.S. Geological Survey, Unknown, photo ID number: U.S. Geological Survey, Reston, VA.
- Type_of_Source_Media: cartridge tape
- Source_Scale_Denominator: 40000
- Source_Contribution:
-
Panchromatic black and white (or color infra-red) NAPP
or NAPP-like photograph. NAPP photographs are centered
on the DOQ coverage area.
- CONTROL_INPUT (source 3 of 4)
-
U.S. Geological Survey, Unpublished material, project ground and photo control: U.S. Geological Survey, Reston, VA.
- Type_of_Source_Media: various media
- Source_Scale_Denominator: Unknown
- Source_Contribution:
-
Horizontal and vertical control used to establish
positions and elevations for reference and correlation
purposes.
- CAMERA_INPUT (source 4 of 4)
-
U.S. Geological Survey, Unpublished material, report of calibration: U.S. Geological Survey, Reston, VA.
- Type_of_Source_Media: disc, paper
- Source_Scale_Denominator: Unknown
- Source_Contribution: camera calibration parameters
- How were the data generated, processed, and modified?
- Date: Unknown (process 1 of 3)
-
The production procedures, instrumentation, hardware
and software used in the collection of standard USGS
DOQ's vary depending on systems used at the contract,
cooperator or USGS production sites. The majority of
DOQ datasets are acquired through government contract.
The process step describes, in general, the process
used in the production of standard USGS DOQ data sets.
The rectification process requires, as input, a user
parameter file to control the rectification process, a
digital elevation model (DEM1) gridded to user
specified bounds, projection, zone, datum and X-Y
units, a scanned digital image file (PHOTO1) covering
the same area as the DEM, ground X-Y-Z point values
(CONTROL_INPUT) and their conjugate photo coordinates
in the camera coordinate system, and measurements of
the fiducial marks (CAMERA_INPUT) in the digitized
image.
The camera calibration report (CAMERA_INPUT) provides
the focal length of the camera and the distances in
millimeters from the camera's optical center to the
camera's 8 fiducial marks. These marks define the frame
of reference for spatial measurements made from the
photograph. Ground control points (CONTROL_INPUT)
acquired from ground surveys or developed in
aerotriangulation, are third order class 1 or better,
and meet National Map Accuracy Standard (NMAS) for
1:12,000-scale. Ground control points are in the
Universal Transverse Mercator or the State Plane
Coordinate System on NAD83. Horizontal and vertical
residuals of aerotriangulated tie-points are equal to
or less than 2.5 meters. Standard aerotriangulation
passpoint configuration consists of 9 ground control
points, one near each corner, one at the center near
each side and 1 near the center of the photograph, are
used. The conjugate positions of the ground control
points on the photograph are measured and recorded in
camera coordinates.
The raster image file (PHOTO_1) is created by scanning
an aerial photograph film diapositive with a precision
image scanner. An aperture of approximately 25 to 32
microns is used, with an aperture no greater than 32
microns permitted. Using 1:40,000-scale photographs, a
25-micron scan aperture equates to a ground resolution
of 1-meter. The scanner converts the photographic image
densities to gray scale values ranging from 0 to 255
for black and white photographs. Scan files with ground
resolution less than 1 meter or greater than 1 meter
but less than 1.28 meters are resampled to 1 meter.
The principal elevation data source (DEM1) are standard
DEM datasets from the National Digital Cartographic
Data Base (NDCDB). DEM's that meet USGS standards are
also produced by contractors to fulfill DOQ production
requirements and are subsequently archived in the
NDCDB. All DEM data is equivalent to or better than
USGS DEM standard level 1. The DEM used in the
production of DOQ's generally has a 30-meter grid post
spacing and possesses a vertical RMSE of 7-meters or
less. A DEM covering the extent of the photograph is
used for the rectification. The DEM is traversed from
user-selected minimum to maximum X-Y values and the DEM
X-Y-Z values are used to find pixel coordinates in the
digitized photograph using transformations mentioned
above. For each raster image cell subdivision, a
brightness or gray-scale value is obtained using
nearest neighbor, bilinear, or cubic convolution
resampling of the scanned image. The pixel processing
algorithm is indicated in the header file . An inverse
transformation relates the image coordinates referenced
to the fiducial coordinate space back to scanner
coordinate space. For those areas for which a
7.5-minute DEM is unavailable and relief differences
are less than 150 feet, a planar-DEM (slope-plane
substitute grid) may be used.
Rectification Process: The photo control points and
focal length are iteratively fitted to their conjugate
ground control points using a single photo space
resection equation. From this mathematical fit is axes
obtained a rotation matrix of constants about the three
of the camera. This rotation matrix can then be
used to find the photograph or camera coordinates of
any other ground X-Y-Z point. Next a two dimensional
fit is made between the measured fiducial marks on the
digitized photograph and their conjugate camera
coordinates. Transformation constants are developed
from the fit and the camera or photo coordinates are
used in reverse to find their conjugate pixel
coordiates on the digitized photograph.
Quality Control: All data is inspected according to a
quality control plan. DOQ contractors must meet DOQ
standards for attribute accuracy, logical consistency,
data completeness and
- Date: Unknown (process 2 of 3)
-
I&M Process: All data has a header file (.hdr) created
based upon the information given within the header
of the actual quarter quad. No information is changed.
This allows the data to be brought up within ArcView as
an image. Data is also renamed based upon standard I&M
vernacular. These names consist of a six letter
abbreviation of the quad along with the two letters
which represent the quadrant the image represents.
- Date: Unknown (process 3 of 3)
-
Metadata imported.
Data sources used in this process:
- C:\DOCUME~1\hwn\LOCALS~1\Temp\xml24.tmp
- What similar or related data should the user be aware of?
- How well have the observations been checked?
During photographic reproduction of the source photography,
limited analog dodging is performed to improve image
quality. Analog dodging consists of holding back light from
certain areas of the sensitized photographic material to
avoid overexposure. The diapositive is inspected to insure
clarity and radiometric uniformity. Diapositive image
brightness values are collected with a minimum of image
quality manipulation. Image brightness values may deviate
from brightness values of the original imagery due to image
value interpolation during the scanning and rectification
processes. Radiometry is verified by visual inspection of
the digital orthophoto quadrangle with the original
unrectified image to determine if the digital orthophoto has
the same or better image quality as the original unrectified
input image. Slight systematic radiometric differences can
be detected between adjacent DOQ files due primarily to
differences in source photography capture dates and sun
angles of aerial photography along flight lines. These
differences can be observed in an image's general lightness
or darkness when compared to adjacent DOQ file coverages.
- How accurate are the geographic locations?
The DOQ horizontal positional accuracy and the
assurance of that accuracy depend, in part, on the
accuracy of the data inputs to the rectification
process. These inputs consist of the digital elevation
model (DEM),aerotriangulation control and methods, the
photo source camera calibration, scanner calibration,
and aerial photographs that meet National Aerial
Photography Program (NAPP) standards. The vertical
accuracy of the verified USGS format DEM is equivalent
to or better than a USGS level 1 or 2 DEM, with a root
mean square error (RMSE) of no greater than 7.0 meters.
Field control is acquired by third order class 1 or
better survey methods sufficiently spaced to meet
National Map Accuracy Staandards (NMAS) for
1:12,000-scale products. Aerial cameras have current
certification from the USGS, National Mapping Division,
Optical Science Laboratory. Test calibration scans are
performed on all source photography scanners.
- How accurate are the heights or depths?
- Where are the gaps in the data? What is missing?
All DOQ imagery is visually inspected for completeness to ensure
that no gaps, or image misplacement exist in the 3.75' image area
or in overedge coverage. DOQ images may be derived by mosaicking
multiple images, in order to insure complete coverage. All DOQ's
are cloud free within the 3.75' image area. Some clouds may, very
infrequently, be encountered only in the overedge coverage.
Source photography is leaf-off in deciduous vegetation regions.
Void areas having a radiometric value of zero and appearing black
may exist. These are areas for which no photographic source is
available or result from image transformation from other
planimetric systems to the Universal Transverse Mercator (UTM).
In the latter case, the void sliver areas are on the outside
edges of the overedge area. The data set field content of each
DOQ header record element is validated to assure completeness
prior to archiving in the NDCDB.
- How consistent are the relationships among the observations, including topology?
All DOQ header data and image file sizes are validated by the
Tape Validation System (TVS) software prior to archiving in the
National Digital Cartographic Data Base (NDCDB). This validation
procedure assures correct physical format and field values for
header record elements. Logical relationships between header
record elements are tested.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
-
None. Acknowledgement of the U.S. Geological Survey would be
appreciated in products derived from these data.
- Who distributes the data set? (Distributor 1 of 1)
USGS/CSS/Core Science Analytics and Synthesis
c/o USGS-NPS Vegetation Mapping Program Coordinator
Denver Federal Center, Building 810, Room 8000, MS 302
Denver, Colorado 80225
(303) 202-4220 (voice)
303-202-4219 (FAX)
gs-b-npsveg@usgs.gov
- What's the catalog number I need to order this data set?
Downloadable Data
- What legal disclaimers am I supposed to read?
The U.S. Geological Survey and the National Park Service shall not be held liable for improper or incorrect use of the data described and/or contained herein. These data and related graphics (if available) are not legal documents and are not intended to be used as such.
The information contained in these data is dynamic and may change over time. The data are not better than the original sources from which they were derived. It is the responsibility of the data user to use the data appropriately and consistent within the limitations of geospatial data in general and these data in particular. Any related graphics (if available) are intended to aid the data user in acquiring relevant data; it is not approriate to use the related graphics as data.
The U.S. Geological Survey and the National Park Service gives no warranty, expressed or implied, as to the accuracy, reliability, or completeness of these data. It is strongly recommended that these data are directly acquired from an U.S. Geological Survey and National Park Service servers and not indirectly through other sources which may have changed the data in some way. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the utility of the data on another system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is also strongly recommended that careful attention be paid to the contents of the metadata file associated with these data. Mention of trade names or commercial products in this metadata report does not constitute endorsement or recommendation for use by the U. S. Department of the Interior, U. S. Geological Survey and National Park Service.
- How can I download or order the data?
- Availability in digital form:
- Cost to order the data: None
- Dates:
- Last modified: 08-Feb-2004
Last Reviewed: 15-Jun-2010
- Metadata author:
-
USGS/CSS/Core Science Analytics and Synthesis
c/o USGS-NPS Vegetation Mapping Program Coordinator
Denver Federal Center, Building 810, Room 8000, MS 302
Denver, Colorado 80225
(303) 202-4220 (voice)
303-202-4219 (FAX)
gs-b-npsveg@usgs.gov
- Metadata standard:
- FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata (FGDC-STD-001.1-1999)
- Metadata extensions used:
-
Generated by mp version 2.9.12 on Tue Jun 15 13:06:41 2010
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