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 and Sextants
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
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 degrees south.
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.
Britannia as it's normally viewed.
Britannia with Lord British's throne in the center.
And the Lost Lands? What of them?
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
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 dimensions.)
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
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
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 disappeared.
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
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
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 boundaries:
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 right.
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
Here are tables that have values for the constants:
latitude (y axis)
longitude (x axis)
The Lost Lands
latitude (y axis)
longitude (x axis)
(* Notice that the same values for N are used in both Britannia and the Lost
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.