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# Relative distance flashcards

to instill in people a good recognition of distance
 (+7, -1) [vote for, against]

How accurate would you be if asked to point to any object 100/500/1000 metres away, or more?

The idea is to create a selection of photographic or computer generated images, which depict a variety of common objects at a selection of set distances.
Imagine, for example, that each picture shows a man, a car and a house, each of average size for the country/community in which they are shown.
The three things are placed side by side within a vast, flat scene (perfectly simple with CGI, photographs would presumably be taken on large expanses of grass/sand/salt or whatever area is available) and would be part of a series in which each image is taken from the next set distance.

The images would be most useful within primary schools, but would still provide useful visual aids to anyone else.

Technical specifications: Some quick research suggests that the images should be produced with a lens at a focal length of about 22mm, to closely approximate the human eye.
Distances depicted in the images would be metric.

 — fridge duck, Jun 30 2009

Estimation Skills Estimation_20Skills
[phoenix, Jun 30 2009]

that would be really nice, for people with one eye. You would be teaching the brain a relatively worthless skill for anyone with any depth perception. Additionally the size of the object is almost never predictable. A short person would be much further away.
 — WcW, Jun 30 2009

//anybody with depth perception//
the over-rated depth-perception sense craps out after 50 yards or so in the average person.
 — FlyingToaster, Jun 30 2009

 // You would be teaching the brain a relatively worthless skill for anyone with any depth perception. Additionally the size of the object is almost never predictable. A short person would be much further away.//

Actually, I'd consider the ability to accurately estimate distances to be pretty useful in a lot of situations, as for the varying size of objects, it's a fair point, but as long as the viewer has at least a rough idea of what they are looking at, it can be compared to such everyday things as the people and cars in pictures.
 — fridge duck, Jun 30 2009

 I'm not sure it would work very well. For one thing, how far does the person hold the "standard image" from their face? This will be important, shirley.

 Also, it really just shifts the problem. When someone is looking at a distant car, for instance, you're asking them to say how big it looks (ie, does it look bigger or smaller than the image of a car at 500 yards), but the visual system makes it very difficult to judge this apparent size unbiasedly. The classic example is the moon which, depending on its position relative to the horizon, can look much larger or much smaller, even though it has the same objective size on the retina.

For this to work, the person would have to hold up the "reference card" (at the correct distance) next to the real object and make a direct comparison.
 — MaxwellBuchanan, Jun 30 2009

 // This sure would make sniper training easier. //

 On the graticule of many telescopic sights, there are crossbars which roughly correspond to the distance between the waist and head of a target at progressively longer ranges. The marksman aims at the belt buckle, then derives from the angular magnitude the probable range and adjusts elevation accordingly.

To work well at ranges beyond a couple of hundred metres, stereoscopic rangefinders require an inconveniently long baseline. This makes them bulky, and heavy - because to retain calibration, they need to be very stiff, like most precision optical devices.
 — 8th of 7, Jun 30 2009

 50 yards? Really? How do we ever judge larger distances when we lack referential objects?

 What are these cards going to have on them, two objects side by side?

 "If the blue house is at 100 yards, how far away is the red house"

I don't buy it. Take the example of the moon, the moon is always the same size and roughly the same distance away when visible so the inconsistency in it's perceived size is a huge blow to this idea.
 — WcW, Jul 01 2009

 //50 yards really?//That's what I was told. Makes sense though: how is your brain going to calculate parallax more than half a football field away from 2 sources 3-4 inches apart ?

Come to think of it, that number seems a bit high and probably includes non-binocular cueing (head bobbing or moving from side to side; all of which can be done with one eye).
 — FlyingToaster, Jul 01 2009

 [21Q] for once has generated a genuine smirk with his comment that they would be useful as long as terrorists dont get their hands on them.

 In actualy fact, it is rare that this would be useful as the assumption relies on the angle of view relative to the ground. It is rare that there will be no gradient, the exception being at sea where the horizon is roughly 5km away (according to QI). In this case the curvature of the earth adds additional complexity.

On the other hand, this is easily baked and would be interesting to see. Does anyone here have 3DSMAX, or even a computer game mapping tool?
 — miasere, Jul 01 2009

 //Distances depicted in the images would be metric.//

 uh-oh!

I learned to (somewhat) judge distance on a road when I was told that telephone poles are approx. 100 ft. apart.
 — xandram, Jul 01 2009

extrapolation. The brain uses binocular vision to establish a frame of reference and rolls that out to the horizon.
 — WcW, Jul 01 2009

21Q, how dangerous are Role Playing Game wielding terrorists?
 — goldbb, Jul 02 2009

Depends on what they roll.
 — jutta, Jul 02 2009

I want a set of terrorist training flashcards! Sounds like far more fun than the anarchists cookbook 'now with pocket size convenience'.
 — WcW, Jul 03 2009

 Having two eyes is only needed for 1 of maybe 7 or 8 different depth perception tools you have at your disposal.

Other examples: -patterns like tiles that get smaller -vanishing points -objects that occlude one another -relative size of an image (you use this already, flash cards or no) -when you're moving, things close to you appear to pass more quickly. -some other things i can't remember.
 — Smurfsahoy, Jul 03 2009

I'm not entirely sure I made the idea as clear as I'd hoped.
I recognise that humans have a variety of ways in which they can determine distances, the point of the flashcards was to aid in assigning numbers to those distances, such that although a person can tell if something is close/ far/ very far, they can translate these basic concepts into useful measurements.
 — fridge duck, Jul 03 2009

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