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A picture, a plane and the flat terrain. Please explain.

  1. Mar 24, 2015 #1
    A problem of photogrammetry

    How can be demonstrated that the terrain in front of the plane you see in the photo is flat and there is no slope going down there?


    Dec-17-1903-Flyer1TakingOffFirstFlight120Feet.jpg
    First flight, 120 feet in 12 seconds, 10:35 a.m, December 17, 1903; Kitty Hawk, North Carolina. Orville Wright at the controls.

    If it helps you can download the entire large size image (TIFF 17.2mb ) here: http://www.loc.gov/pictures/item/00652085/
     
    Last edited: Mar 24, 2015
  2. jcsd
  3. Mar 24, 2015 #2

    Simon Bridge

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    You use the clues in the photo - look at what the terrain consists of, objects on the terrain, and shadows.
    Extrapolate from apparent height of the camera. It helps if you know the dimensions of some of the objects photographed.

    In general a photograph is a 2D projection of a 3D structure, so information is lost.
    You have to use other knowledge about the situation to recover the missing data.

    The easy approach is just to look up the location the picture was taken and go there and measure (or use a geological survey).
    Since it is a natural setting, the ground is unlikely to be "flat". For the first piloted etc flight, only the launch was level, using rails, s I see no reason to suspect the ground is all that flat for the entire course. But then, I've never been to Kitty Hawk, maybe it's a noteably flat place.

    What do you need to know for?
     
    Last edited: Mar 24, 2015
  4. Mar 24, 2015 #3

    DrClaude

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    I think that what the OP is after is if the ground is level or not, which you can't tell from a picture.
     
  5. Mar 24, 2015 #4

    Simon Bridge

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    In general you cannot tell from a picture ... however in a picture of hills, to take an extreme example, it's a fair bet that the ground is not level.
    There are other possible clues - some of them in the picture above - which can help.

    But the context is important.
     
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