How far out?

[Railak]

So the party is trying to intercept a battalion of 600 soldiers, two characters can fly. How far out can they see them if they went say 500 ft up where the horizon is 80(ish) miles out. I know that it's basically impossible to see a single human at that range, but what about an army formation of 600?

[Zaq]

Do you want an answer based on physics or based on D&D Spot rules? Because they're not the same.

[gijoemike]

Mountains can been seen from 100 miles away given atmospheric distortion at certain times of the day. This is from https://www.city-data.com/forum/general-u-s/950840-whats-farthest-distance-you-can-see.html. Mt Rainier is one of the largest mountains in the lower 48 states of the USA.



On an exceptionally clear and cloudless day (probably only a few times a year), you can see Mount Rainier from Everett, WA, which is about 75 miles.

So, you're asking if given a good vantage point if you can make out a shape of a group of 6" tall figures 80 miles away? I would say not a chance. If they had head to toe uniforms of one contrasting color It would be blobs of color and even then they would need to be a sharp contrast to the ground, foliage, and there cannot be a tree, building, or a tall bush anywhere close to the army to even see that blob of color. If this was a near flat desert and the army was wearing black and green armor then maybe a high perception/spot character could make out line or circle. In perfect lighting & weather btw. If it is raining, cloudy, or windy with dust storms/pollen then that means no chance again.


I would like point out that distance drops the spot/perception check very quickly. And at a MILE out there is a harsh penalty to those rolls. The army may not be hiding and is wearing shiny distinctive armor. And may have large warriors and animals. And there is modifiers to large groups as well. This would be a flat dc 0 to spot them but then with all the modifiers one could have -100 to -200 DC to see them. But at 80 miles the perception/spot check may need to be in the 1000s. Every 100" is a +1 modifier to the DC. There is over 5k feet per mile. That is a modifier of over +100 DC per mile. I grant you that seems dumb as characters would be unable to see Mt. Rainier if a mountain started with a -1k DC to spot.

Even if as a GM you decide to run it as +1 DC per 1000 ft it is still a +5 DC per mile. At 80 miles that would be +400 DC to spot them. +200 at 40 miles. Even with massive negatives for visibility and being in the open I doubt even an optimized character could see them AT ALL.


BRINGING THAT IN

At about 30 miles out that would be a 150 modifier to the DC if one ran the +1 per 1k". 30 miles is a full days march/ride for troops based on the Roman legion travel times. So one would be able to see vague shapes if the uniform contrast against the background. Decent perception characters could make out shapes and formations and number of camps. One could seem them and begin to prepare at 1 days travel. It also seems climatic enough.

[InvisibleBison]

Bear in mind that the Spot rules are only used to see hiding creatures or to determine the distance at which an encounter begins. If the people you're trying to spot aren't hiding and you're not going to attack them as soon as you see them, Spot doesn't come into play.

[Biggus]

Given D&D Spot rules, it's impossible to see anything past a few hundred feet away (a large object in plain sight is given a Spot DC of 0, meaning that even with a Spot score of 40 and a natural 20, you can only see it from 600ft).

In real life, you can resolve a single person at a distance of about 1.6-2 miles. If 600 people are marching together in a tight, roughly square formation you could treat them as single creature about 25 times larger, which would mean you could see them at about 40-50 miles.

As for a general rule, larger creatures get a Hide penalty of -4 per size category, ie per doubling of height. If you continue to give objects larger than colossal an additional -4 penalty for every height doubling, and double the distance for a Spot penalty every -4 (so 20ft for each point from -5 to -8, 40ft for -9 to -12 and so on) you get a system for long-range Spot which makes some kind of sense.

Edit: just noticed that Stormwrack (page 89) has basic rules for spotting at long distances, if you want something official I think those are the closest thing there is answering to your question.

[Fouredged Sword]

I would say it depends on the terrain and what the 600 people are doing.

In an open plane and with the 600 people not trying to be stealthy with their camps?

Well, if they fly up at night they are going to see campfires from a good distance away. In dark conditions you can see a candle at 30 miles. Also, in a camp setting they are going to have multiple fires going for that number of men, and that means smoke.

But change any of those conditions and ability to see drops off significantly. Any sort of obstruction like rolling hills is going to cut off vision after not that many miles. Anything like dense forest is going to render them unable to see at all through the foliage period, even if they flew directly over the target. If the 600 man group is trying to be stealthy they won't have fires... Then it may be impossible to see them at 80 miles, because any obstruction would block line of sight and SOMETHING would exist in those 80 miles blocking vision.

[RNightstalker]

At 500 ft, I don't think that will be far enough to see anything at 80 miles. IIRC normal maximum sight on a clear sunny day is ballpark 20-25 miles, simply due to the curvature of the earth. As far as seeing Mt. Rainier, it's also has a peak of 14,410 ft. The best solution I can think of is a network of spies, maybe the party Druid wildshapes into an animal that's native to the area.

[Palanan]

Originally Posted by gijoemike
So, you're asking if given a good vantage point if you can make out a shape of a group of 6" tall figures 80 miles away? I would say not a chance.

Absolutely agreed.


Originally Posted by RNightstalker
IIRC normal maximum sight on a clear sunny day is ballpark 20-25 miles, simply due to the curvature of the earth.

An average-height person standing at ground level can see a maximum of 12 miles due to the earth’s curvature, assuming perfectly smooth terrain.

Even at that range there will be complications from a host of factors. Trying to spot a group of people 80 miles away is effectively impossible due to humidity, atmospheric distortion, etc.

At best, if the air is unnaturally clear and still, and if the troop formation is walking through a dry, dusty area, you might be able to see a hint of the dust cloud they raise—but even then, that would be tiny and virtually impossible to spot from 80 miles out.

[RNightstalker]

At best, if the air is unnaturally clear and still, and if the troop formation is walking through a dry, dusty area, you might be able to see a hint of the dust cloud they raise—but even then, that would be tiny and virtually impossible to spot from 80 miles out.

Thanks for the correction on the distance of sight and mentioning the possible dust cloud. That was on my mind to mention but apparently forgot.

Of course there's also the thing that some armies will march to music...and the listen penalty is the same as the spot penalty, +1/10 ft. I would think there's a possibility considering wind and canyon conditions that the army will be heard before it is seen.

[Elkad]

By the Spot rules, you can't see the Moon.

Average human can make out another moving human at a mile or so, especially if they stand out from the background. (Bright armor, motion, etc).
For example, you can make out climbers more than a mile from you as you stand on the ground near Half-Dome. Motion (even rather slow deliberate climbing motion) and bright clothes makes them easy to pick out.

Adventurers aren't average.

Best recorded human vision (Veronica whatshername from Germany) can tell two people in identical clothing apart by their face at a mile in good conditions.

But atmospheric distortion kicks in somewhere. You might see *something* moving at 10 miles, but whether it's an army or a flock of sheep or just a shadow from a lonely cloud moving across the ground? Doubtful you could make that distinction.

[InvisibleBison]

By the Spot rules, you can't see the Moon.

Unless the moon is hiding from you or you're trying to fight it, you absolutely can see the moon because the Spot rules aren't used.

[RNightstalker]

By the Spot rules, you can't see the Moon.


lol well said, but I imagine the moon and stars will take a pretty big size modifier hit to their hide check:tongue:

[Biggus]

Unless the moon is hiding from you or you're trying to fight it, you absolutely can see the moon because the Spot rules aren't used.

Well, that depends on which part of the PHB you focus on. On page 83 it says


The Spot skill is used primarily to detect characters or creatures who are hiding. Typically, your Spot check is opposed by the Hide check of the creature trying not to be seen. Sometimes a creature isn’t intentionally hiding but is still difficult to see, so a successful Spot check is necessary to notice it.

However, on page 64 we have


DC 0 (very easy) Notice something large in plain sight (Spot)

Given the conditional language in the first quote (primarily, typically, sometimes) it's certainly not ruled out for the DM to call for a Spot check to see the moon, and given the DC in the second quote, if it's more than a few hundred feet away, it would take an astronomical (no pun intended) Spot check to see it.

[Saintheart]

If they're looking to intercept a battalion of 600 soldiers, the presumption is that said soldiers are moving. The dust kicked up as those soldiers walk is visible from quite a distance out, that's as old as Sun Tzu. Also the reflected light off their weapons and armour, which flashes like signal mirrors.

[Lapak]

Yeah, using a mountain as a point of comparison I'm thinking of the last time I hiked up one that gives a clear view at the top. You increase the distance to the horizon, but things many miles away are also then too tiny to see. And contrary to what we think of when we think of 600 soldiers, they don't move around in battlefield-style blocks - an army of 600 marching is going to be doing it a few abreast, meaning you're looking for a long thin line of people moving and not a single big blob - hard to pick out on a road. And eyes don't have infinite resolution in terms of how we process vision, either; with the unaided human eye, you can only start identifying something person-sized as more than essentially a pixel in your field of view at 3ish miles out. Tracking a group, and a moving group at that, would definitely help. I agree that it does very much depend on terrain - if they are hiking on a road in open terrain like farmland (not through a forest) and if conditions are dry enough, you might be able to see the dust... but still probably not at 80 miles out. You might get lucky with that or with reflections assuming that they are a spit-and-polish force with shiny metal showing, but it would take some luck / a good spot check.

As for hearing them before seeing them, well, maybe, but only if you're not spotting them until they are pretty darn close to you. Like, within a mile or two close, unless they are specifically trying to project noise. Canyons were mentioned - that absolutely makes hearing more likely and seeing a LOT less likely.

[ciopo]

facetiously thought but actually serious in hindsight : are you on a prime plane that has a curvature? You could realistically be somewhere the "flat X" movement is actually right :D

Consider also the fluff part of spells such as hawk eye or eye of the avoral and the likes. Other than the mechanical effect of spot bonus, you can still ballpark the physic part of "an eye better than human"

If you want to get fancy-cheesy, see what your DM feels about the interaction of allied swarms and the spell linked perception

[Fizban]

Stormwrack's section on Spot for spotting at sea, which will have been based on the same sort of research presented above, gives a flying creature a couple hundred feet in the air a range of 12 miles to spot a "small boat" (likely a Huge object), or 25 miles to spot a sailing ship. As mentioned, a moving army will likely dust up quite a cloud, which could make it as "tall" as a sailing ship, and if they have any sort of raised banners they should be at least as tall as a "small boat".

[Fouredged Sword]

Unless the moon is hiding from you or you're trying to fight it, you absolutely can see the moon because the Spot rules aren't used.

And it was when they looked up and realized the moon was missing from the sky that they realized their troubles had just begun.

"Someone stole the moon?" Tekara asked incredulously.

"Nobody could steel the moon." Jorak grimaced. "No, this is worse. The moon has decided to attack."

[InvisibleBison]

Well, that depends on which part of the PHB you focus on. On page 83 it says



However, on page 64 we have



Given the conditional language in the first quote (primarily, typically, sometimes) it's certainly not ruled out for the DM to call for a Spot check to see the moon, and given the DC in the second quote, if it's more than a few hundred feet away, it would take an astronomical (no pun intended) Spot check to see it.

Text trumps table.

[Railak]

Okay cool, so roughly 20-30ish miles seems to be the general consensus except the part about spot check rules, which are both hilarious and extremely awkward. The 80 miles thing was the horizon, I knew it wouldn't be that far out. Sorry if I confused anyone there.

And damn this got a lot of responses xD thank you community.

Actually touching on the "spot check" shinanigans, did you know it's impossible for a village of commoners, or someone with 10 (or less) wisdom and no bonuses/ranks in spot, to see a great wyrm red dragon past 370 ft standing outside a village? 470 ft if it's fighting something.

[Crake]

Stormwrack actually has spot rules for spotting other ships on the horizon which could be well extrapolated for this scenario. If we assume that the army of six hundred is about as noticable as a sailing ship, and we reverse the roles of the observer and the observed, we have "Flying: An observer at least a couple of hundred feet in the air (well above the masthead of even the largest sailing ships)." A flying observer gets a DC20 spot check to notice a sailing ship at 25 miles, and automatically spots the ship at half that distance. If the roles were reversed, a grounded observer would get a dc20 spot check to observe a flying ship at 25 miles, and automatically notice it at half that distance. Again, assuming that a battalion of 600 flying soldiers is roughly as noticable as a ship, seems like fairly translatable rules.

[Biggus]

Text trumps table.

The text doesn't contradict the table.

[InvisibleBison]

The text doesn't contradict the table.

The text says you don't need to make a Spot check to see something that isn't hiding; the table says you does. What is that if not a contradiction?

[Jay R]

This will be a DM judgment call, based on many things.

In real life, a walking or riding army in a world with no pavement was often spotted by the huge dust storm they kick up, and in dry weather, a large army can sometimes be spotted even while they are beyond the horizon.

[Zaq]

And it was when they looked up and realized the moon was missing from the sky that they realized their troubles had just begun.

"Someone stole the moon?" Tekara asked incredulously.

"Nobody could steel the moon." Jorak grimaced. "No, this is worse. The moon has decided to attack."

72 hours remain

[Biggus]

The text says you don't need to make a Spot check to see something that isn't hiding; the table says you does. What is that if not a contradiction?

Where is the text which says "you don't need to make a Spot check to see something that isn't hiding"? I can't find it.

[Crake]

Where is the text which says "you don't need to make a Spot check to see something that isn't hiding"? I can't find it.

Guessing he's referring to this?


The Spot skill is used primarily to detect characters or creatures who are hiding. Typically, your Spot check is opposed by the Hide check of the creature trying not to be seen. Sometimes a creature isn’t intentionally hiding but is still difficult to see, so a successful Spot check is necessary to notice it.

Sounds to me like the requirement for a spot check is "Difficult to see" or "Intentionally hiding".

[InvisibleBison]

Guessing he's referring to this?



Sounds to me like the requirement for a spot check is "Difficult to see" or "Intentionally hiding".

Yes, that's the section I was referring to.

[Melcar]

So the party is trying to intercept a battalion of 600 soldiers, two characters can fly. How far out can they see them if they went say 500 ft up where the horizon is 80(ish) miles out. I know that it's basically impossible to see a single human at that range, but what about an army formation of 600?

The -1 to spot per 10 ft. is only for things that are using hide... or that are difficult to see, like a small butterfly... Therefore its basically whether or not its a clear day or whether or not there are vegitation or mountain blocking your sight. Off the top of my head I would say 10 miles out at least... given optimal conditions.

[bean illus]

Stormwrack actually has spot rules for spotting other ships on the horizon which could be well extrapolated for this scenario. If we assume that the army of six hundred is about as noticable as a sailing ship, and we reverse the roles of the observer and the observed, we have "Flying: An observer at least a couple of hundred feet in the air (well above the masthead of even the largest sailing ships)." A flying observer gets a DC20 spot check to notice a sailing ship at 25 miles, and automatically spots the ship at half that distance. If the roles were reversed, a grounded observer would get a dc20 spot check to observe a flying ship at 25 miles, and automatically notice it at half that distance. Again, assuming that a battalion of 600 flying soldiers is roughly as noticable as a ship, seems like fairly translatable rules.


Yes.

Spot/Hide rules are only for things the GM thinks are hiding or hidden.

Armies do not walk in a line (though troops do), they stay as close together as feasible. The entire history of the world has revolved, and resolved on this.

Contrary to Hollywood, the average soldiers armor is not polished to a mirror.

Boats are easy to see at sea, because they are the only thing there.

A dust plume in a dry landscape can be seen against the sky, but from the ground. From 500' up, the dust would be hard to see.

Due to curvature about 10 miles for a large house, when both are at ground level.

Stormwrack's rules attempt to account for both the height of the observer, and the observed.

I would say, that on a dry, cloudless, windless day, you could use the Stormwrack rules to spot the dust at 25 miles, from the ground.

On a windy, cloudy day, you could use the same rules to "automatically spot ... at half that distance", from 500' up vantage (or even crow's nest height of 100').

[Jay R]

A dust plume in a dry landscape can be seen against the sky, but from the ground. From 500' up, the dust would be hard to see.

Good observations, overall. I just wanted to comment on this line.

A lookout who flies up to 500 feet doesn't live there. She is looking all the way up and all the way down. She will see things that can best be seen at 500 feet, but she will also see the things that can best be seen at 200 feet, or at ground level.

[Fouredged Sword]

Also a lookout is likely to be taking 20 when it comes to spotting any ongoing event like a formation of soldiers on the march. Taking a spot check is a move action and so taking 20 is a matter of minutes. When someone declares that they are going to actively look for something they should be taking 20 unless the event is time critical in that they don't have a few minutes to look or that the thing they are looking for is only visible for a short time.

And a second person going up to help them can, rather than make a second spot check, act like a spotter and aid other granting the first person taking 20 a +2.

[bean illus]

Good observations, overall. I just wanted to comment on this line.

A lookout who flies up to 500 feet doesn't live there. She is looking all the way up and all the way down. She will see things that can best be seen at 50 feet, but she will also see the things that can best be seen at 200 feet, or at ground level.

Yes.
But only if the spotter understands this, and mentions it to the GM.
If the spotter(s) leave the ground before sunrise, or on a cloudy morning, or during wind, or dampness, the dust is invisible.

I saw no reference to the amount of resource available. If infinite flying is possible, one can stay in the air all day. But in that case one can fly towards the army, considerably reducing the spot distance.

It needs to be noted though, that two party members hundreds of feet in the air will leave two party members alone on the ground.

[Fouredged Sword]

Yes.
But only if the spotter understands this, and mentions it to the GM.
If the spotter(s) leave the ground before sunrise, or on a cloudy morning, or during wind, or dampness, the dust is invisible.

I saw no reference to the amount of resource available. If infinite flying is possible, one can stay in the air all day. But in that case one can fly towards the army, considerably reducing the spot distance.

It needs to be noted though, that two party members hundreds of feet in the air will leave two party members alone on the ground.

Though downward flight is at double speed and a run action is possible, meaning a 500ft drop can be done in about two turns with most flight methods.

30ft fly speed means 60ft drop speed, with run actions being 4x move speed, so 240 feet a round.

[bean illus]

Though downward flight is at double speed and a run action is possible, meaning a 500ft drop can be done in about two turns with most flight methods.

30ft fly speed means 60ft drop speed, with run actions being 4x move speed, so 240 feet a round.

Assuming one has remained directly over your party, and that they didn't lose surprise, and that you don’t mind saving them after 3 rounds.