Being a treatise on the
world and how to navigate it.
Is Britannia a sphere...
...or a torus?
The world of Britannia is intended to represent a sphere similar
to the planet Earth. However, it is really a flat rectangular
world and should you happen to sail off the end of it, you will
be magically teleported to the opposite end.
The geometric solid that most accurately represents this
behavior is a torus (or a donut shape for those of you who
may not be mathematically inclined) but to say that the world
is a torus would not be completely accurate because Britannia
is exactly the same distance across no matter where on the
map you happen to measure it and a torus would demonstrate
some warping effect. But no matter, we'll suspend our disbelief
for a moment and say that the world is like a donut.
All of this is important to understand because, like Earth,
places in Britannia are located using a coordinate system
that uses latitudes and longitudes.
Latitudes and Longitudes
On the planet Earth, locations can be identified using a
system that divides the world into lines of latitude and longitude.
Latitude is measured by degrees north or south of the Equator.
There are 360 degrees in a circle. Each degree is further
divided into 60 minutes. That means that any point on the
planet Earth is between 90 degrees 0 minutes north of the
equator (the North Pole) and 90 degrees 0 minutes south of
the Equator (the South Pole).
Longitude is measured by degrees east or west of the Prime
Meridian (an imaginary vertical line that passes through Greenwich
England). Any point on the planet Earth is between 180 degrees
0 minutes east and 180 degrees 0 minutes west of the Prime
Meridian (which would happen to both represent the same place
on the exact opposite side of the globe from the Prime Meridian
but that's only confusing the issue).
On Earth, latitude was traditionally determined by using
a sextant, a device which, when aimed at the North Star, Polaris,
would tell you how many degrees above the Equator you were
at. (In southern latitudes you can use the star Sigma Octantis
which is the closest star to the southern celestial pole.)
Determining longitude is more difficult and requires precise
clocks. (This need played an enormous part in advancing science
during the early days of global navigation on Earth.)
In Britannia, clocks are only useful for telling time and
sextants magically provide longitude as well as latitude,
although it appears that the heavens are still in some way
involved since they don't work underground.
Enough already! Just tell
me how it works!
Alrighty. Here you go.
The center of Britannia's coordinate system is Lord British's
throne which is at 0 degrees latitude and 0 degrees longitude.
Due to some strange magic, it was decided that Britannia
shall have 360 degrees latitude as well as 360 degrees longitude.
This means that, unlike Earth, you can find places in Britannia
that are in latitudes greater than 90 degrees north and 90
Furthermore, the degrees wrap when you reach 180. That means
that once you pass 180o north, you begin counting down from
180o south. (On Earth this behavior is limited only to longitude
since you can't go any farther north than the North Pole.)
As if that weren't confusing enough, Lord British's throne
is not in the exact center of our magical rectangular teleporting
land. This means that there is a band at the bottom of the
map where locations have north latitudes and there is a band
at the right of the map where locations have west longitudes.
And the Lost Lands? What of
The Lost Lands use exactly the same system, except that
the center is located in the middle of the Shallow Sea. Also
the Lost Lands are much smaller and are surrounded by an impenetrable
barrier. Therefore, you can't go far enough from the center
for the latitude and longitude values to wrap.
What about Felucca and Trammel?
Beginning with Ultima Online Renaissance, the world of every
UO shard (except Siege Perilous) was divided into two worlds:
Felucca and Trammel. (They're named for the two moons of Britannia
although, curiously, they don't actually reside on the two
moons; they're really more like a pair of linked alternate
Felucca is the older of the two worlds. This is the player
vs. player world that has been overrun by Minax and her forces.
Trammel is the newer world. This world is a little more
friendly (and therefore, some would say, a little less exciting).
Player vs. player actions are strongly regulated.
Both Felucca and Trammel use the exact same world map so
you could kind of view them as being two separate shards except
for the fact that players can travel between them by using
moonstones found throughout the game.
And what about Ilshenar?
With Ultima Online: Third Dawn (UO3D), a new land was added
to the game: the land of Ilshenar.
Ilshenar uses a completely separate map from the other lands
although it shares exactly the same coordinate system.
It is quite a bit smaller than Britannia at roughly one
sixth the surface area.
This is what it looks like:
So what are Tile Coordinates?
As has been shown above, latitudes and longitudes are a
little cumbersome in Britannia. Particularly when you take
into account the fact that the world is made up of a flat
rectangular grid of discrete tiles.
Tile coordinates, also known as X.Y coordinates,
also known as where coordinates, give a place's exact
location in number of tiles, measured from the upper left
hand corner of the map. Using tile coordinates Lord British's
throne is located at 1323.1624. That's the 1323rd tile from
the left and the 1624th tile from the top.
Since sextants only give coordinates for places that are
above ground, tile coordinates are the only way to identify
locations in the dungeons. Also, since all of Britannia and
the Lost Lands are really located on the same rectangular
map, the same tile coordinate system may be used for both.
For some time, in addition to the normal latitude and longitude
readings, sextants also reported these coordinates, along
with an additional Z coordinate that gave an indication of
altitude (X.Y.Z). In February of 1999 this ability magically
Latitude and longitude are expressed in UO using a notation
where the symbol o indicates degrees and the symbol
' indicates minutes. For example, the location 44o
38'N 122o 0'W represents 44 degrees 38 minutes north latitude,
122 degrees 0 minutes west longitude.
UOAM adds a suffix to locations to indicate which world
they belong to: (B) for Britannia, (LL) for
the Lost Lands.
Locations that can't be expressed in latitude and longitude
(areas on the dungeon map) are always displayed in tile coordinates.
Tile coordinates are given in X.Y notation. For example,
the location 44o 38'N 122o 0'W (B) when displayed as
tile coordinates is written like this 4708.1116.
Ultima Online's flat rectangular magical teleporting map
has another strange characteristic that is worth mentioning.
Much like our Earth is made up of different geologic plates
separated by fault lines, Britannia is divided up into server
zones separated by server boundaries.
A UO shard is managed by a set of game servers. When you
cross a server boundary, management of your character is passed
from one game server to another.
At Earth's fault lines, odd things (such as earthquakes
and volcanoes) tend to happen. At Britannia's server boundaries
odd things also tend to happen. I will leave it up to you
to figure out what those odd things might be.
One of UOAM's features is that it can show you exactly where
those server boundaries are. Here then is a screen shot taken
from UOAM that shows the complete game map and all the server
Note that as of this writing, no server boundaries have
been discovered in Ilshenar.
I continue to receive requests to post the algorithms to
convert from one system to another. Unfortunately the algorithms
are a little bit troublesome as they require precise rounding
to get exactly the correct results for a given location and
the rounding doesn't always work the way you would expect.
It took a lot of trial and error to get the routines exactly
Unless you are extremely curious and have a relatively high
aptitude for algebra, you might want to stop reading right
here. It only gets more confusing from here on out.
The easiest way to convert between the two is to use UOAM
but for the die hards among us, here you go...
The algorithms presented here are simplified algorithms
that will get you close (within a minute or a tile depending
on which way you're going).
To convert from tile coordinates to latitude and longitude,
run each component through the following formula:
d = (t - C) * 360 / N
|| = degrees (multiply the
part to the right of the decimal by 60 to get minutes)
|| = tile position
|| = center tile position
|| = width or height of the
map at that point
This formula works for both latitude and longitude and it
works for both Britannia and the Lost Lands.
This formula always returns east longitudes and south latitudes
and so the result needs to be normalized. If d is greater
than 180 or less than 0, you will probably want to adjust
it appropriately. (I didn't say it would be easy.)
Here are tables that have values for the constants:
||latitude (y axis)
||longitude (x axis)
|The Lost Lands
(* Notice that the same values for N are used in both Britannia
and the Lost Lands.)
||latitude (y axis)
||longitude (x axis)
To convert back to tile coordinates, normalize the position
so it is expressed in terms of east longitude and south latitude
and then run each component through the following formula:
t = d * N / 360 + C
Finally, normalize t
to ensure that 0 <= t < N by adding or subtracting N as necessary.
This document is courtesy of
, author of UO Auto-Map.