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Oregon / Washington

GIS Metadata

BLM OR Aerial Photography Centers Point

Frequently-asked questions:

What does this data set describe?

BLM OR Aerial Photography Centers Point

ap_centers_point: This point dataset depicts the centers of the photo frames for aerial photography taken over BLM Lands in the states of Oregon and Washington.

  1. How should this data set be cited?

    Bureau of Land Management, Oregon State Office, 20151009, BLM OR Aerial Photography Centers Point.

  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -124.594198
    East: -116.467820
    North: 49.006723
    South: 41.838188

  3. What does it look like?

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

    Calendar date: 20151009
    Currentness reference:
    publication date

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

    Geospatial data presentation form: vector digital data

  6. How does the data set represent geographic features?

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

      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Entity point (366009)

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

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 2.0000000000000001e-009. Longitudes are given to the nearest 2.0000000000000001e-009. Latitude and longitude values are specified in Decimal Degrees.

      The horizontal datum used is D North American 1983.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.

  7. How does the data set describe geographic features?

    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    Number assigned to the film roll. (Source: BLM)

    The number assigned to the flight line.  Historically, R was used for reflights, G was used for Gap flights.  Flightline segments, after 1998, were numbered with decimals (14.0, 14.1, 14.2, etc.). (Source: BLM)

    Number assigned to each frame of photos. (Source: BLM)

    Letters assigned to each frame of photos in addition to numbers. (Source: BLM)

    Compilation of Roll, Flight, Exposure, and Sub_Exposure (Source: BLM)

    Date photos within a flight line were flown, if available. (Source: BLM)

    Time (Pacific Standard) photos were taken within a flight line, if available.  In the case of more recent projects, the time recorded is the time the flight line was completed.  For instance, the flight starts at 12:51 and ends at 12:43, then 12:51 is recorded as the PhotoTime. (Source: BLM)

    Project code used as a unique identifier. (Source: BLM)

    BLM District project is located within. (Source: BLM)

    USGS Quadrangle Name (Source: BLM)

    Recreation Site name  (Source: BLM)

    BLM Resource Management Area Name (Source: BLM)

    Scanned image path and name (Source: BLM)

    Longitude of approximate center of the image. (Source: BLM)

    A relative description of the photo position in the flight line; Start, Middle, End.  (Source: BLM)

    Latitude of approximate center of the image. (Source: BLM)

    Project code used as a unique identifier. (Source: BLM)

    The amount of rotation required to align the photo with north at the top as viewed. Values given in degrees. (Source: BLM)

    The status of the represented photo in the scanning process.  (Source: BLM)

    Project flight line code used as a unique identifier. (Source: BLM)

    The ratio of a distance measured on a photograph to the corresponding distance on the ground. (Source: BLM)

    Entity and attribute detail citation:
    Individual photo centers are in a point feature class, created from digital files.  
    Since 2001, contractors have collected GPS photo centers at the instant of exposure and provided them in digital form.  Where GPS obtained photo centers were not available, BLM scanned mylar or paper indexes and registered them to a projection before digitizing the photo centers.  In some cases, BLM digitized every fifth photo center and allowed a software program to interpolate the positions of the photo centers in between.  Those photo points are identified as "I" in the "Type" field of the attributes.
    Although BLM cannot verify, in each individual case, how historical indexes were made, it is presumed that the contractor who flew the photography identified the photo center positions and marked them on a mylar or paper map.
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Who produced the data set?

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

    • Bureau of Land Management, Oregon State Office

  2. Who also contributed to the data set?

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

    Corey Plank
    Bureau of Land Management
    Lead Cartographer
    P.O. Box 2965
    Portland, OR 97201

    (503) 808-6427 (voice)
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Why was the data set created?

This feature class is intended to facilitate the location and identification of BLM aerial imagery in Oregon and Washington for release to BLM district personnel, other agencies and the general public. This theme can be used to search and display photo locations as well as for the creation of flight index maps.

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How was the data set created?

  1. Where did the data come from?

  2. What changes have been made?

    Date: unknown (change 1 of 6)
    This point data was captured by the contractor who flew the project area, or by BLM Oregon/Washington State Office employees. The photos were examined and a centerpoint of each frame was located on a mylar or paper map. The map is used as an index to the project. A BLM employee scanned the index map at 300 dots per inch and then geo-registered the scanned index. The employee digitized the photocenter points in ArcMap, sometimes every point and sometimes every fifth point. The Type attribute indicates whether the point was individually located or located by a script that interpolated points in between the fifth points. The feature class has two attribute fields indicating which point locations were interpolated.

    Person responsible for change:
    Susan Nelson
    Bureau of Land Management
    Cartographer/Remote Sensing Acquisition
    P.O. Box 2965
    Portland, OR 97204

    (503) 808-6139 (voice)

    Data sources used in this process:
    • Scanned Lat Lon

    Date: not complete (change 2 of 6)
    Corrected photo location information and added additional points

    Person responsible for change:
    Corey Plank
    BLM Oregon State Office
    Lead Cartographer
    PO Box 2965
    Portland, OR 97208-2965

    503-808-6145 (voice)
    503-808-6190 (FAX)

    Date: 20120423 (change 3 of 6)
    Individual project data were aggregated into this feature class. Field names were standardized (given common names). Data was projected to GCS North American 1983 Datum.

    Person responsible for change:
    Eric Hiebenthal
    Bureau of Land Management, Oregon State Office
    GIS Data Management Specialist
    P.O. Box 2965
    Portland, OR 97208

    503-808-6565 (voice)
    503-808-6419 (FAX)

    Date: 20131220 (change 4 of 6)
    Added additional photo locations.

    Person responsible for change:
    Corey Plank
    USDI Bureau of Land Management
    Lead Cartographer - Remote Sensing
    PO Box 2965
    Portland, OR 97208-2965

    503-80-6145 (voice)

    Date: 20150518 (change 5 of 6)
    Reloaded with additional/revised data

    Person responsible for change:
    Steve Salas
    U.S. Bureau of Land Management, Oregon State Office
    GIS Specialist/ArcSDE Administrator

    Date: 20150901 (change 6 of 6)
    Added additional attributes to use for tracking, query, and display of photo points and status of scanning project.

    Person responsible for change:
    Corey Plank
    BLM Oregon State Office
    Lead Cartographer
    PO Box 2965
    Portland, OR 97208-2965

    503-808-6145 (voice)
    503-808-6190 (FAX)

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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?

    90% of the centerpoints are within 400 feet of their actual position.

  3. How accurate are the heights or depths?

    Not applicable.

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

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

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How can someone get a copy of the data set?

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

Access constraints: PUBLIC DATA. None, these data are considered public domain.
Use constraints:
These data are provided by Bureau of Land Management (BLM) "as is" and might contain errors or omissions. The User assumes the entire risk associated with its use of these data and bears all responsibility in determining whether these data are fit for the User's intended use. The information contained in these data is dynamic and may change over time. The data are not better than the sources from which they were derived, and both scale and accuracy may vary across the data set. These data might not have the accuracy, resolution, completeness, timeliness, or other characteristics appropriate for applications that potential users of the data may contemplate. The User is encouraged to carefully consider the content of the metadata file associated with these data. These data are neither legal documents nor land surveys, and must not be used as such. Official records may be referenced at most BLM offices. Please report any errors in the data to the BLM office from which it was obtained. The BLM should be cited as the data source in any products derived from these data. Any Users wishing to modify the data should describe the types of modifications they have performed. The User should not misrepresent the data, nor imply that changes made were approved or endorsed by BLM. This data may be updated by the BLM without notification.

Distributor 1 of 1

  1. Who distributes the data set?

    Eric Hiebenthal
    Bureau of Land Management
    GIS Data Management Specialist
    P.O Box 2965
    Portland, OR 97208

    503-808-6340 (voice)
    503-808-6419 (FAX)
    Contact Instructions:
    contact instructions

  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    The BLM assumes no responsibility for errors or omissions. No warranty is made by the BLM as to the accuracy, reliability, or completeness of these data for individual use or aggregate use with other data; nor shall the act of distribution to contractors, partners, or beyond, constitute any such warranty for individual or aggregate data use with other data. Although these data have been processed successfully on computers of BLM, no warranty, expressed or implied, is made by BLM regarding the use of these data on any other system, or for general or scientific purposes, nor does the fact of distribution constitute or imply any such warranty. In no event shall the BLM have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of the use or reliance on the geographic data or arising out of the delivery, installation, operation, or support by BLM.

  4. How can I download or order the data?

    • Cost to order the data: Contact distributor.

    • Special instructions:

      Data are only available through the Oregon/Washington State office of the Bureau of Land Management.

  5. Is there some other way to get the data?

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

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Who wrote the metadata?

Last reviewed: 20150202

Metadata author:
Roger Mills
Bureau of Land Management, Oregon State Office
GIS Specialist
P.O. Box 2965
Portland, OR 97208

(503) 808-6340 (voice)
(503) 808-6419 (FAX)
Hours of Service: 8:00-4:00
Contact Instructions:

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata(FGDC-STD-001-1998)

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