Visible distance? Question about how far you can see....


Gamer Life General Discussion

Shadow Lodge

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If your 300' in the air and the sky is crystal clear, and the land is flat with visible marks, how far can you see with normal (20/20) vision?


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Apparently, 21.2 miles. Assuming you're on earth. And not looking at space.


That's, what, about a +11,141 increase to the DC (it works out to 11,140.8, but you round up, you know)? Well, given that you did give us "favorable conditions", that's probably only +11,139 or (if you're a really lenient GM, you cheater) +11,138 to the Perception DC.

O_O


Tacticslion wrote:

That's, what, about a +11,141 increase to the DC (it works out to 11,140.8, but you round up, you know)? Well, given that you did give us "favorable conditions", that's probably only +11,139 or (if you're a really lenient GM, you cheater) +11,138 to the Perception DC.

O_O

Only if what you want to spot is standing on the horizon. Otherwise you will need some more maths :-p


:)

Sovereign Court

By that logic Tacticslion, nobody can see the sun.


EDIT 2: The moon, too!

You did note that I linked to the actual skill description, yes?
(It's one of those places that PF doesn't quite model reality very well.)

EDIT: I think the "logic" (if you wish to apply Perception rules to such things) is that things larger than colossal (for which the sun certainly qualifies) have ever-increasing "penalties" to their "stealth" modifier (effectively lowering the Perception DC to "find" them - and they aren't even actively hiding). Notice that the Perception DC to "Hear sounds of battle" is -10. I'd wager that the sun being, you know, the sun would have a far larger penalty.

Now, all that said, it's possible that we're just "doing it wrong" if we apply the perception skill at all.

From the link I provided above,

Perception, under 'Check' wrote:

Perception has a number of uses, the most common of which is an opposed check versus an opponent's Stealth check to notice the opponent and avoid being surprised. If you are successful, you notice the opponent and can react accordingly. If you fail, your opponent can take a variety of actions, including sneaking past you and attacking you.

Perception is also used to notice fine details in the environment. The DC to notice such details varies depending upon distance, the environment, and how noticeable the detail is. The following table gives a number of guidelines.

In other words, although "number of uses" is vague, the only two "hard" rules for Perception is to oppose stealth and to notice fine details in the environment. Since when it is behind the earth, it has total cover and total concealment (EDIT 2: though I suppose, by the rules, that would only give it a +20 to it's stealth check...), it makes sense that you wouldn't be able to find the sun at night (though the moon oft gives its presence away, the cheeky devil), but it's certainly true that, staring right at the sun, we're unable to "notice fine details", as, you know, we can't see them.

Added to that, there's probably more than a little similarity to a blur effect going on, due not only to atmospheric distortion, but also the sheer brightness of the thing (in contravention to normal light and vision rules) means that, without super-special equipment (like, say, something that let's us mitigate some of those Perception penalties) we wouldn't be able to make out "fine details" anyway. Broad details, yes. But not fine ones.

EDIT 2: Notice how difficult it is to pick out fine details of things as large as planets, even if they're not nearly as far away as the Sun without specialized equipment? It can even be difficult to find them! Further, it's possible to have stars (like the Sun, but even larger or brighter!) be so far away that we can't see them at all. And some are entirely lost with galaxies that we can barely make out.

Point being, there are plenty of elements within the skill that could be reasoned out to allow such absurd-seeming numbers without saying "you can't see that far". :D


Pretty sure the sun has a circumstance bonus of +10 billion for I dunno being a celestial sized burning inferno in space that can be seen from millions of miles away from planets


MattR1986 wrote:
Pretty sure the sun has a circumstance bonus of +10 billion for I dunno being a celestial sized burning inferno in space that can be seen from millions of miles away from planets

Pst. I think you mean "the sun has a circumstance penalty of -10 billion" or some similar wording, as we're talking about the Perception DCs of such things; or "the sun provides a viewer a circumstance bonus of +10 billion for purposes of seeing it" or something similar. I'm a helper! :D


Lol however you want to word it but ya, distance in this case doesn't matter.


:)

(Also kind of covered in my edit above that, but yours was probably started before the edit was completed, and I could see people walking away with a different conclusion. Either way, we're cool. :D)


To go back to the op think about looking out a window of an airplane. When looking out how far can you see? How far can you see movement? Realistically you could see movement for miles


I always thought the perception rules were for noticing fine details or hidden enemies rather than how far a character could see.

Shadow Lodge

What I was wondering was how far you could see different terrain features, such as forests, mountains, lakes, etc.

Not as far as I'd hoped. Terrain 500+ miles away isnt visiable.


Like I said, use common sense of what you can see on a clear day from an airplane before you ascend to 5k feet.


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Jacob Saltband wrote:

What I was wondering was how far you could see different terrain features, such as forests, mountains, lakes, etc.

Not as far as I'd hoped. Terrain 500+ miles away isnt visiable.

The 21.2 miles calculation assumes you're looking at something on the horizon. Hills and mountains rising far above the horizon will be visible from further away.

A mountain in the 6000 - 7000 feet range could be seen 100 miles+ away from sea level, and more from 300 feet above.

500 miles seems a bit much 'tough


Given line of sight (the link in the second post gives the horizon distance for a given height) the optical limit of what you can resolve (based on a wavelength of 550nm and a pupil diameter of 5mm) would be about 0.13mm at 1m and would scale proportionately. This is the theoretical limit of optical resolution - in reality the object would probably need to be a bit bigger than that.

So, if a human is about 400mm wide under good conditions you could theoretically be able to resolve them at about 3,000,000 mm or 3km (2 miles). However, as a real life practical example, I can just about make out people silhouetted against the sky on a hilltop at 1.5km (about 1 mile). So, for heroes with brilliant eyesight, maybe 1.5 miles would be the limit to see a medium sized creature/object with sufficient contrast. How far you can make out hills, lakes, woods etc will depend on how big they are.

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