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

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Discussion Overview

The discussion revolves around the problem of determining whether the terrain depicted in a historical photograph of the Wright brothers' first flight is flat or sloped. Participants explore the challenges of photogrammetry and the limitations of visual information in photographs.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using clues from the photo, such as terrain features, objects, and shadows, to infer the flatness of the terrain.
  • Another participant emphasizes that a photograph is a 2D projection of a 3D scene, which results in lost information, necessitating additional context to recover data about the terrain.
  • It is proposed that measuring the actual location or consulting geological surveys would provide definitive answers about the terrain's flatness.
  • Some participants express skepticism about determining the levelness of the ground solely from the photograph, noting that context is crucial for interpretation.

Areas of Agreement / Disagreement

Participants generally agree that a photograph alone cannot definitively indicate whether the ground is level or not. However, there are competing views on the extent to which contextual clues can aid in this determination.

Contextual Notes

Participants acknowledge the limitations of relying on a photograph for terrain analysis, including the loss of three-dimensional information and the need for additional measurements or context to draw conclusions.

simplex1
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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/
 
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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?
 
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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.
 
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.