Niihau Photomosaic 2000 (115-0511) - Orthorectification and Mosaicing of Color Aerial Photography Main Eight Hawaiian Islands

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Frequently anticipated questions:


What does this data set describe?

Title:
Niihau Photomosaic 2000 (115-0511) - Orthorectification and Mosaicing of Color Aerial Photography Main Eight Hawaiian Islands
Abstract:
Habitat maps of the main Hawaiian Islands were created by visual interpretation of aerial photos and hyperspectral imagery using the Habitat Digitizer extension. Aerial photographs are valuable tools for natural resource managers and researchers since they provide an excellent record of the location and extent of habitats. However, spatial distortions in aerial photographs due to such factors as camera angle, lens characteristics, and relief displacement must be accounted for during analysis to prevent incorrect measurements of area, distance, and other spatial parameters.

These distortions of scale within an image can be removed through orthorectification. During orthorectification, digital scans of aerial photos are subjected to algorithms that eliminate each source of spatial distortion. The result is a georeferenced digital mosaic of several photographs with uniform scale throughout the mosaic. Features near land are generally georeferenced with greater accuracy while the accuracy of features away from land is generally not as good. Where no land is in the original photographic frame only kinematic GPS locations and image tie points were used to georeference the images. After an orthorectified mosaic is created, photointerpreters can accurately and reliably delineate boundaries of features in the imagery as they appear on the computer monitor using a software interface such as the Habitat Digitizer.

  1. How should this data set be cited?

    O'Mara, Greenhorne & , 20020102, Niihau Photomosaic 2000 (115-0511) - Orthorectification and Mosaicing of Color Aerial Photography Main Eight Hawaiian Islands: Greenhorne & O'Mara, Greenbelt, MD.

    This is part of the following larger work.

    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Program, 2002, Benthic Habitats of the Main Hawaiian Islands Prepared by Visual Interpretation from Remote Sensing Imagery Collected by NOAA Year 2000: NOAA's Ocean Service, National Centers for Coastal Ocean Science (NCCOS), Silver Spring, MD.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -160.2507
    East_Bounding_Coordinate: -160.1257
    North_Bounding_Coordinate: 21.9968
    South_Bounding_Coordinate: 21.8787

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2000
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: remote-sensing image

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set.

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 4
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -159
      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 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 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.

  7. How does the data set describe geographic features?


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Program
    Biogeography Team Leader, Mapping Manager
    1305 East West Highway, N/SCI-1
    Silver Spring, MD 20910

    301-713-3028 (voice)
    301-713-4388 (FAX)
    matt.kendall@noaa.gov

    Hours_of_Service: 0800-1700, Monday to Friday, EST


Why was the data set created?

The National Ocean Service is conducting research to digitally map biotic resources and coordinate a long-term monitoring program that can detect and predict change in U.S. coral reefs, and their associated habitats and biological communities.


How was the data set created?

  1. From what previous works were the data drawn?

    Hawaiian Color Aerial Photographs (source 1 of 3)
    Department of Commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Geodetic Survey (NGS), 2000, Color Aerial Photographs Main Hawaiian Islands Collected by NOAA Year 2000: NOAA's Ocean Service, National Geodetic Survey (NGS), Silver Spring, MD.

    Online Links:

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 24000
    Source_Contribution: Photographs were scanned and orthorectified.

    DEM (source 2 of 3)
    United States Geological Survey, 200111, digital elevation models: U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: cartridge tape
    Source_Contribution:
    Elevation data was used to correct for relief displacement in the photographs.

    GCPs (source 3 of 3)
    Analytical Laboratories of Hawaii, 2002, ground control points: Analytical Laboratories of Hawaii, Kailua, Hawaii.

    Type_of_Source_Media: various media
    Source_Contribution:
    Fixed ground features visible in the scanned photos were selected for GCPs which were then used to georeference the imagery

  2. How were the data generated, processed, and modified?

    Date: 2002 (process 1 of 1)
    Aerial photographs were acquired for the main Hawaiian Islands Benthic Mapping Project in 2000 by NOAA Aircraft Operation Centers aircraft and National Geodetic Survey cameras and personnel. Approximately 1,449, color 9x9 inch photos were taken of the coastal waters of the main Hawaiian Islands at a 1:24,000 scale.

    Prints and diapositives were created from the original negatives. Diapositivies were then scanned at a resolution of 500 dpi using a photogrammetric quality scanner, yielding one by one meter pixels for the 1:24,000 scale photography. All scans were saved in TIFF format for the purposes of orthorectification and photointerpretation.

    Georeferencing/mosaicing of the TIFFs was performed using a variety of softcopy photogrammetric software including Socet Set Version 4.2.1, Autometric Softplotter, PCI OrthoEngine, and Erdas OrthoBASE. First, lens correction parameters were applied to each frame to eliminate image distortion. Airborne kinematic GPS was then used, to provide first order georegistration.

    Image to image tie-points were then used to further co-register the imagery, especially for photos taken over open water when ground control points were not available. Fixed ground features visible in the scanned photos were selected for ground control points (GCPs) which were then used to georeference imagery. GCPs were measured using a Differentially-corrected Global Positioning System (DGPS). We obtained points with a wide distribution throughout the imagery, especially on peninsulas and outer islands whenever possible since this results in the most accurate registration throughout each image. Only ground control points for terrestrial features were collected due to the difficulty of obtaining precise positions for submerged features.

    Pre-existing USGS 10-meter digital elevation models were used to correct for relief displacement

    Person who carried out this activity:

    Greenhorne & O'Mara
    Attn: Bill Frohn
    Technical Director
    9001 Edmonston Rd
    Greenbelt, Maryland 20770

    301-220-2591 (voice)
    301-220-1877 (FAX)
    wfrohn@g-and-o.com

    Hours_of_Service: 0800 - 1700, Monday to Friday, EST
  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    Average spatial accuracy of individual photomosaics is reported in Chapter 3 of Benthic Habitats of the Main Hawaiian Islands. Positional accuracy was determined by solution of Softplotter generated model (RMS less than 1) and by comparison to independent ground control data. The georegistration of these photographs is at least 95% sigma RMS of 5 meters.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    No color balancing was attempted since this alters color and textural signatures in the original imagery and interferes with the photointerpreter's ability to delineate habitats. As a result mosaics have visible seams between adjacent photos. This provides the photointerpreter with "true color" imagery for maximum ability to identify and delineate benthic features.

  5. How consistent are the relationships among the observations, including topology?

    Once all of the photographs were orthorectified, the best segments of each photograph were selected for creation of the final mosaic. Segments of each photograph were selected to minimize sun glint, cloud interference, and turbidity in the final mosaic. Where possible, parts of images obscured by sun glint or clouds were replaced with cloud/glint free parts of overlapping images. As a result, most mosaics have few or no clouds or sun glint obscuring bottom features.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints: None

  1. Who distributes the data set? (Distributor 1 of 1)

    National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Program
    Biogeography Team Leader, Mapping Manager
    1305 East West Highway, N/SCI-1
    Silver Spring, MD 20910

    301-713-3028 (voice)
    301-713-4388 (FAX)
    matt.kendall@noaa.gov

    Hours_of_Service: 0800-1700, Monday to Friday, EST
  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA and NODC cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) produced this data CD-ROM. NCCOS Biogeography Program does not guarantee the accuracy of the geographic features or attributes.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    The user may utilize a variety of software to view the imagery mosaics (MrSID files), including ENVI, PCI, Arc GIS or ArcView 3.1ó or higher and the "MrSID Image Support" Extension turned on.


Who wrote the metadata?

Dates:
Last modified: 18-Sep-2014
Metadata author:
National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Program
Biogeography Team Leader, Mapping Manager
1305 East West Highway, N/SCI-1
Silver Spring, MD 20910

301-713-3028 (voice)
301-713-4388 (FAX)
matt.kendall@noaa.gov

Hours_of_Service: 0800-1700, Monday to Friday, EST
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.13 on Thu Oct 23 10:42:40 2014