Humans have an intuition of when two objects or places are close or far away from each other which is seems to be relative rather than absolute. One might say that Germany is close to France, my house is close to the supermarket, etc., and then say that two plants in the backyard are far from each other.

Even when this is subjective, based on what do we classify two objects as being far, close, or somewhere in-between? Is it just the the size of the objects? what about objects of very different sizes like a house and a pen?

What about the distance from us to the objects? Would we consider two trees to be close when we are very far away, but then consider them far away when we are close to them?

What are the parameters that we base this decision on?

How would a computer classify two objects in such a way that it "mimics" the human decision.

  • 2
    $\begingroup$ Context (as you already highlighted in a couple of examples) ... surely? Not sure what you are hoping to find here, as you already answered it yourself. Try to refine the question to narrow it down. As is, I believe this question is too broad. $\endgroup$
    – Steven Jeuris
    Commented Jul 12, 2017 at 12:46
  • 1
    $\begingroup$ @StevenJeuris I'm trying to find what parameters should a computer use to answer if two objects are close or far away. $\endgroup$
    – Girauder
    Commented Jul 12, 2017 at 14:43
  • 1
    $\begingroup$ I'm voting to close this question as off-topic because although this has a cognitive basis, this has nothing to do with Cognitive Sciences $\endgroup$ Commented Jul 14, 2017 at 11:15
  • $\begingroup$ @Chris I disagree, since it appears that OP is trying to create a cognitive model, which is in the scope of this site $\endgroup$
    – Seanny123
    Commented Jul 16, 2017 at 19:55
  • $\begingroup$ I don't understand why this question is closed? The relative nature of the senses is a fundamental property of vision, hearing and touch, and perhaps the other senses too. I would strongly vote to re-open this question. $\endgroup$
    – AliceD
    Commented Jul 25, 2017 at 13:17

2 Answers 2


Long comment, so writing as an answer... I have to agree with @StevenJeuris: use context.

For example, you could establish some magnitude scale for a comparison (this is your context), then compare the distance between objects as a percentage of the magnitude.

Which magnitude to use? This is entirely subjective. In human behavior, individuals certainly can and do disagree on whether objects are close or not (depending on the context they are considering). An astrophysicist may consider any object on a single planet "close" to each other, while a microbiologist may consider any separation that can be seen with the naked eye to be "far".

To answer "what parameters do you base the decision on," consider the question "close as compared to what?" For the example of trees above, you may consider it as "close/far, as compared to my distance from the tree," but again, there are more complex pieces (personal history, etc) that also come into play. You could program that (for the astrophysicist, keep the default comparative distance as an interplanetary or interstellar distance), but you'd have to make an active decision regarding the purpose of your program.

Perhaps one other thing to remember: there is no "normal", necessarily. Everyone can look at comparative distance differently, and there isn't much of an objective standard to dictate someones comparison as "right" or "wrong", there is simply what they are comparing to (and then we may be able to get into "correct" and "incorrect" comparative distances).

  • 1
    $\begingroup$ Thanks for your answer! Although it's not exactly what I was expecting, what you say about the "Context" does give me a good insight. I could consider as "context" the distance between a subject and one of the objects, and based on that determine if the other object is close or far away $\endgroup$
    – Girauder
    Commented Jul 26, 2017 at 2:36

If understood your question well you are looking for depth perception:

Depth perception is the visual ability to perceive the world in three dimensions (3D) and the distance of an object.

The depth perception is achieved by specific cues in our environment :


The property of parallel lines converging in the distance, at infinity, allows us to reconstruct the relative distance of two parts of an object, or of landscape features. An example would be standing on a straight road, looking down the road, and noticing the road narrows as it goes off in the distance.

Relative size

If two objects are known to be the same size (e.g., two trees) but their absolute size is unknown, relative size cues can provide information about the relative depth of the two objects. If one subtends a larger visual angle on the retina than the other, the object which subtends the larger visual angle appears closer.

Aerial perspective

Due to light scattering by the atmosphere, objects that are a great distance away have lower luminance contrast and lower color saturation.


Occultation (also referred to as interposition) happens when near surfaces overlap far surfaces. If one object partially blocks the view of another object, humans perceive it as closer.


When an object is visible relative to the horizon, we tend to perceive objects which are closer to the horizon as being farther away from us, and objects which are farther from the horizon as being closer to us

see the complete list of cues at wiki.

For furter reading see Visual Thinking: for Design By Colin Ware

  • $\begingroup$ Thanks for your response. Unfortunately it is not depth perception what I'm talking about, but it could be somewhat related. I don't know why my previous comment wasn't posted so sorry to respond so late. $\endgroup$
    – Girauder
    Commented Jul 26, 2017 at 2:20

Not the answer you're looking for? Browse other questions tagged or ask your own question.