Seeing at a distance

[skip.knox]

I had a practical question: from what distance could my MC be able to see the enemy approaching?

There are lots of variables here, including how many are the enemy, my MC's elevation, whether it's bright or cloudy, and so on. But in looking around I found some useful articles, so I thought I'd share.

How far away is the horizon? - Bad Astronomy | DiscoverMagazine.com : Bad Astronomy
How Far Can the Human Eye See? | Human Visual Acuity
system agnostic - A summary of visibility? - Role-playing Games Stack Exchange
(one can always count on the role playing folks for this sort of thing)
Re: On a dark night, how far away can a person see a lit candle?

 

[Svrtnsse]

I've done a fair bit of walking around the countryside lately. For what it's worth I can with confidence say that if I stand on one hilltop I would not be able to see a person standing on the next hilltop. It'd be too far away.
This assumes standard Irish-countryside hills.

EDIT:
Definition intentionally left super-vague.

 

[Matthew Bishop]

Eh, you'd hear an army before you see it in almost any case, unless you happen to be high up along a mountain ridge on a perfectly clear day with almost no tree or cloud cover beneath you. Noise is the first alert when there is such a large group. A smaller individual company would be the only thing you might see before hearing.

 

[Trick]

For this sort of thing, I like personal experience but it's hard to gauge unless you have vast expanses near where you live. I happen to be so lucky but not everyone is. I have pretty decent vision (20/15) and I have a friend with even better than that. I used to think that the variation in people's vision (within the average spectrum) didn't make a massive difference. Well, over great distances, it definitely does.

One day my friend and I were looking for a Lowe's we were told was on a certain highway. We crested a hill and he says, "There it is, right there." Pointing and everything. I follow his finger and can see nothing to indicate a Lowe's sign. Seeing my lack of comprehension, he says, "The sign's blue, big white letters that say Lowe's."

Duh...

The only blue thing in sight is about the size of a dot to my eyes so I ignore it and look harder, thinking I'm just missing something obvious in plain sight. About another half-mile later the blue dot seems to be both blue and white to me. Another half-mile and it clearly says Lowe's.

He could read it from that much farther than me and I can read the bottom line on an ophthalmologist's chart at thirty paces. How much better must his vision be than my wife's when she can't read 20 size font on our TV screen ten feet away?

It certainly explains why he's a semi-pro sharpshooter. But it also helped me understand how much human vision really varies.

Thought this might be an interesting addition.

 

[skip.knox]

The bit about vision led me directly to a similar question about hearing. Oddly, I was unable to find a decent resource, probably because the variables with hearing are even greater. Even so, it'd be worth knowing if a person could, say, hear another person shouting from a mile away. From two miles. And so on. Knowing the rough parameters would help keep me from saying something completely stupid.

[Edit] - had a brainstorm and searched on "shouting distance". Found this
Distance a shouting person can be heard - Absolute Write Water Cooler
The whole thread is interesting.

And no, I'm not going to wonder how far away we can smell things. Not today, anyway!

 

[CupofJoe]

Shouting at a mile? Yes - assuming still air and no obstructions. I doubt you could understand more then "Hey".
Shouting at two miles? I would say no, but I've watched and listened to Sheepdog trialling at least 2 miles away on the other aside of a valley [there was about a 12s delay]. It was a still warm day and you could here the PA pretty well but you could also clearly hear the whistles of the contestants and the occasional dog bark and sheep bleat...

 

[skip.knox]

Good information, CupofJoe. It's becoming increasingly clear to this lifelong city dweller that writing a fantasy novel involves a number of practical questions like this, to which I have nearly useless insight. Such as: on a quiet night I can hear a car horn from five blocks away, does that help?

 

[CupofJoe]

Glad to help.

Such as: on a quiet night I can hear a car horn from five blocks away, does that help?

I don't know what a block is [1/8 of a mile? I'd call that a Furlong...] but I live about half a mile or more from a major road and I have woken up because there was NO traffic noise on it...
It is great in snowy weather, I can listen for the road and if I hear it I have to "try" to get to work...
But getting back to your original question... It is movement that I notice most when out walking... I can see a walker 2-3-4 miles away if they incongruous against the background... and 20-30 yrds if they aren't....
So not much help there... Sorry.

 

[stephenspower]

Here's the answer from Minute Physics, including the mechanics of sight: "How Far Can Legolas See"?

 

[Penpilot]

Here's the answer from Minute Physics, including the mechanics of sight: "How Far Can Legolas See"?

Great link.

It shows what the reality of sight is, (very useful) but also, it illustrates the point that in stories, you can, within reason, have your characters see at the distance of plot. The same with hearing.