How does a world without a sky determine directions?

[Trekkin]

I'm working on a setting for DnD 3.5 primarily out of intrigue at interesting things I've learned about how perception and communication shape each other; cultures with more words for a specific color, for instance, test as being able to discriminate between smaller variations in that color.
In that vein, I'm positing a world rather like some variations of the Elemental Plane of Earth, only without the crushing pressure. It's simply an infinite expanse of stone riddled with inhabited tunnels, and its sentient inhabitants are not recent enough arrivals to have any idea what a sky is.

So, assuming a total lack of sunlight, stars, or ambient magnetic force (arbitrary decision), and an almost absolute lack of a directional gravity except in the largest caverns given the relatively uniform distribution of mass around any given point, how might these poor people establish a frame of reference for navigation? Would they, even, have any equivalent for North?

(I'm still working on an ecology to replace photosynthesis and a geology that somehow allows the surrounding stone to disappear, although at present I'm going with "arcanosynthetic" bacteria as the autotrophs and some mechanism causing the stone to slowly dissipate into energy below a critical mass, because if it's as hard as I want it to be to crowd everyone together, I need a reason why armor isn't made out of it.) It's the cultures, and how they might deal with directions sans an extraterrestrial frame of reference,that are leaving me bemused, and as such I thought I'd present the problem to the Playground and see if anyone else would find it a sufficiently intriguing puzzle.

[hamishspence]

In that vein, I'm positing a world rather like some variations of the Elemental Plane of Earth, only without the crushing pressure. It's simply an infinite expanse of stone riddled with inhabited tunnels, and its sentient inhabitants are not recent enough arrivals to have any idea what a sky is.

Aren't parts of the Plane of Earth already like that- riddled with passages- and some big open caverns? If I remember rightly, the dao (earth genies) reside in The Great Dismal Delve- a collection of large caverns- and dominate the plane.

[Trekkin]

Aren't parts of the Plane of Earth already like that- riddled with passages- and some big open caverns? If I remember rightly, the dao (earth genies) reside in The Great Dismal Delve- a collection of large caverns- and dominate the plane.

They do indeed, and next time I'll do more Googling on the sources of my world ideas. Do the dao use compasses or something, then?

[dsmiles]

I would imagine that, being natives of the plane, they have another way to figure it out. See, underground, compasses can be completely useless, as they are based on magnets, and a deposit of any ferrous metal could throw it off. Unless, of course, it uses *maaaaaaaaaaagiiiiiic* instead of magnetism to determine direction.

[The Rose Dragon]

So, assuming a total lack of sunlight, stars, or ambient magnetic force (arbitrary decision), and an almost absolute lack of a directional gravity except in the largest caverns given the relatively uniform distribution of mass around any given point, how might these poor people establish a frame of reference for navigation? Would they, even, going to have any equivalent for North?

A frame of reference would be the biggest cavern known. Establish a single monument in it, and record directions on it. Teach everyone these directions and find a way to create three-dimensional compasses that point towards this monument (magic is useful, if you have magic).

True three-dimensional navigation is not really something humans know much of, though, considering we have the earth's core and the magnetic poles as a reference no matter how far we go, and we don't really travel in the outer space.

[jseah]

Since alot of the place will be filled with tunnels, I'd approach the problem from a pathfinding perspective.
Essentially, how do you store the places you've seen and which other places they connect to?

I imagine they'd remember places as corridors and chambers. Then simply remember some kind of connectivity map between them.
They would also have a much better grasp of 3D space than humans do and should have no problems translating entire maps into a new frame of reference. This is because instead of remembering things on a deformed 2D grid, they also have to remember which chamber is above/below which other chamber.

[teslas]

Before the invention of the compass, if we had no celestial sphere, we'd have had no way to discern direction apart from landmarks. I assume this is the same for your people.

You have two options:

1.
Visual cues and general survival knowledge. Creatures simply remember where they are based on what they can see, the changes in apparent rock composition (color, hardness, etc, maybe even odor). This would make navigation of large areas extremely tedious and amazingly complex, but look at grizzled old cab drivers in metro areas. They actually CAN recognize an immense amount of landmarks.

It is still possible for inhabitants to make completely straight tunnels using rather mundane means, so that could be a grid of reference.

Some creatures in such an environment may have no real working grasp of a constant direction. They simply know that left, left, up, down, straight, left, left, right, right again at the black rock, and then down brings them back home. There are plenty of people in our world that have absolutely no sense of direction but navigate about their lives successfully enough.

2.
It's D&D. Magic. If there's no magnetic "north," maybe the inhabitants developed some sort of central point of easy magical detection. Maybe some sort of magic devices they happen to call compasses always point at it. You seem like the sort of person to wonder about how useful compasses are when you're near the north pole, so this would be an issue in your game as well. However, any person with 9+ INT could probably understand to use such an instrument anyway. IE: if it is possible to move in a straight line, you can carefully mark how far the needle moves, thereby determining, roughly, the distance between yourself and magical "north."

Such a device might take a bit of Survival or Knowledge to use extremely well, and it might be anywhere from common to fairly rare in your game world.

Maybe this point is far, far away, rendering the device very usable for direction (in two dimensions). Maybe it's fairly close, making it very usable for determining distance from the source.

Maybe there are two such points or three, so you can have somewhat accurate navigation in three dimensions. Maybe there are more, with a network you can attune each "compass" to, providing a whole myriad of possible navigational sitautions. This system leaves the complexity, usability, and awesomeness up to you and how much time you want to think about it.

edit- 5:00am word mistake corrections

[jseah]

Maybe there are two such points, so you can have somewhat accurate navigation in three dimensions.

Two points will only allow you to triangulate your position onto a circle. Assuming you know how far the two points are apart.

[GodGoblin]

Hmm well even though its pitch black if creatures can see colour or at least shade in the dark then you could have different hues of rock gradually getting more intense towards a certain point. So North would have black rock, east- yellow, west- brown, south- red. And the closer to the centre of the plane you are the lighter the rock and the further out the darker. So to travel in a south easterly direction from the centre towards the outside of the plane you would look for red and yellow hues getting darker.

That probably wont work but its just a thought.

Or maybe have vibration coming through the rock from a certain area that would let people know where they are in relation to a certain point.

[Psyx]

Frame of reference needs to be measurable. And that's not viable in two dimensions given lack of magnetic field. Not in any way that springs to my mind, anyhow. Unless perhaps the temperature of the caves is warmer in one direction than another.

However, toss the third dimension in, and we've got depth.

How deep one is in the chasms will give a variance in pressure which could be measured barometrically.

[teslas]

Two points will only allow you to triangulate your position onto a circle. Assuming you know how far the two points are apart.

Yes yes maths and such. I meant to say "two or three" originally. Fixed now.

I don't think the players want to have to learn trig to play in this campaign, though, or maybe they're starting at level 6 and one of them has a cohort from Leadership that knows what's up... ...pun intended after the fact.

[Trekkin]

How are you getting variances in barometric pressure without a single direction for gravity, though? I thought atmospheric pressure was a function of the weight of air and thus reliant upon gravity, although I could be wrong.

Hmm...is there any variant on Sending that works for all targets in range who know the effect is active? Magical GPS might work.

[teslas]

Hmm...is there any variant on Sending that works for all targets in range who know the effect is active?

There sure is, Mr. DM. Right after you make it.

Magical GPS might work.

I should have just said magical GPS and saved myself all the typing...

[Eldan]

You might use something similar to a Gyro compass. Which has the requirement that your plane has to rotate, sadly.

[Trekkin]

I should have just said magical GPS and saved myself all the typing...

Actually, all that typing, as you put it, was tremendously helpful in making me think about what exactly this bizarre stone that allows this plane to exist actually is; if it's sufficiently heterogeneous, they can, in fact, navigate by omnipresent landmarks, and depending on how I get the social structure working I don't think I'll want that.

[Ytaker]

If they were in such a realm, they might use a frame of people. If you want to go somewhere, you go see someone who lives there. Say by using the second level spell locate object.

[Psyx]

How are you getting variances in barometric pressure without a single direction for gravity, though?

There's not a single direction for gravity? I must have missed that.
Ignore the suggestion.


To be honest, lack of directions really isn't that much of a problem for 99.99% of the population, as they won't be travelling further than the local market-cavern.

[Hubert]

Some thoughts:

* If it is possible, build some magical poles and engineer a device that indicates the direction of these poles. In order to triangulate the position, several (at least 3) of these poles should exist. Or you could have one pole for each big settlement in your world. Instead of "North Pole" and "South Pole", you'd have "City 1 pole", "City 2 Pole", ...

* In this sub-terranean world, the concept of direction should be quite different from ours. Instead of moving on a plane (forward, backward, left, right), you move in 3 dimensions (same, plus top, bottom). For instance, compasses should be built from a sphere instead of a disk, so that the needle could also point up/down.

* Without enough magical poles to triangulate your position, maps become vital. When moving in 2 dimensions it is very difficult to correctly evaluate your position when you have no visual landmarks or compass as reference (for example, in a maze). In 3 dimensions it would be nearly impossible. Thus buying or drawing good maps should be one of the top priorities for everyone planning to venture outside of well-known roads.

[hamishspence]

In 3 dimensions it would be nearly impossible. Thus buying or drawing good maps should be one of the top priorities for everyone planning to venture outside of well-known roads.

And keep them updated- the Plane of Earth tends to crush passages after a while (with the native creatures possibly opening new ones)- caverns are kept open through magic or digging.

It's not static- things change over time.

[Psyx]

I imagine that any travelling group would make sure they had a wand of Lay of the Land!

[Accersitus]

I'm assuming a mostly static set of caves and tunnels

Without any good points of reference, I would think
the best way of navigating would be if someone had
gradually mapped out the caverns from some arbitrary
point (a big cavern/their home). They could then place
marker stones giving the coordinates for that spot in
relation to the center point.

This would make navigation possible (but difficult since
you have to follow the tunnels), and would also give you
an uncharted wilderness that might need magic to navigate
safely.
Directions would then be given as a set of coordinates,
indicating the coordinates one should aim for at junctions
in the tunnels.

If magic was used while mapping out the tunnels, it would
be even better.

[Yora]

Even more important than if there's a north and south, is the question if there's an up and down? Without an agreement which direction is down, left and right also become meaningless.

[Psyren]

So, assuming a total lack of sunlight, stars, or ambient magnetic force (arbitrary decision), and an almost absolute lack of a directional gravity except in the largest caverns given the relatively uniform distribution of mass around any given point, how might these poor people establish a frame of reference for navigation? Would they, even, have any equivalent for North?

Without a sky, magnetism or gravity I don't see how they can know their way around. Was there a pressing reason for removing the latter two?

[Eldan]

If it's the plane of earth, it's infinite in all directions. At least gravity would be problematic. Magnetism could perhaps work, or at least be handwaved.

[Hubert]

Even more important than if there's a north and south, is the question if there's an up and down? Without an agreement which direction is down, left and right also become meaningless.

There is an up and down if there is a gravity with constant direction. A gravity with random direction could give some Escher-esque results

[Gravitron5000]

If it's the plane of earth, it's infinite in all directions. At least gravity would be problematic. Magnetism could perhaps work, or at least be handwaved.

Just because the plane is infinite in all directions, does not mean that the density is uniform in all directions. If the plane was structured so that the density increases as you travel in one direction, than that direction would be 'down'. You would probably also need a limit on the smallest density possible, as there is likely a limit to how little density you can have while still treating the plane as solid.

[Eldan]

True... canonically, the plane of earth does have four poles, more or less, namely Magma, ooze, mineral and sand. Sand, at least, would be less dense than the others, since it's described as a loose mixture of sand and air, so directional gravity could be possible.

of course, the books also say the PoE doesn't have directional gravity, so...

[Yora]

On the plane of earth, every surface is a floor. No idea what causes this gravity, but down is completely subjective to an individuals position.

[Vladislav]

So, assuming a total lack of sunlight, stars, or ambient magnetic force (arbitrary decision), and an almost absolute lack of a directional gravity except in the largest caverns given the relatively uniform distribution of mass around any given point, how might these poor people establish a frame of reference for navigation? Would they, even, have any equivalent for North?

Yes, they would. Because moss always grows on the North side of a cave. Why? Nobody knows. It's just always been like that.

[Eldan]

On the plane of earth, every surface is a floor. No idea what causes this gravity, but down is completely subjective to an individuals position.

That's what I meant, though my wording was bad. There is no gravity in a single direction.