Thursday 8 November 2012

Known Worlds 3D Mapping

How to do it

3D maps are a bit more fiddly that 2D ones, but far from impossible to do.

Step 1
Make a 10x10 grid of squares on a big (A3 or more) bit of paper or computer graphics file. Hexes are OK, but squares are easier to draw, and once you get beyond jump 2 it's as much of a pain to work out distances as it is with squares.

Number it 0-9 along the X and Y axes.

Step 2
Roll 1000d10. Or do what I did and use a spreadsheet. Do it by groups of 10, one group for each square of map, and note where in the sequence of d10s you got a 1, stick a spot in your square with a number on it for each 1 you got, the number being the Z axis (how far 'up' your system is), again using 0-9. Some squares will have no planets, some multiples, just jig 'em about so they fit.

Example: I roll 7, 1, 3, 10, 4, 6, 7, 1, 3, 7. I put spots marked 2 and 8 in my square. If the tenth one had come up a one I'd have put 0, we want a range from 0-9. Makes writing the positions a tiny bit easier in the UPP, you just put xyz as three digits without having to stray into hexadecimals and use A for 10.

On the example map I used a bit of colour coding as well, easy to do with a graphics program.

Step 3
Eyeball your map and look for planets close together and mark key jump routes. I'm going to explain this by long-winded stages as I know maths evades many people.

Now to be generous I'm allowing Jump 1 ships to cover everything out to 1.99 parsecs, anything short of 2, Jump 2 covers 2 to 2.99, Jump 3 out to 3.99 and so on.

Distance between two points is √(x2 + y2 + z2), where x, y and z are the distances on the x y and z axes. Set up a widget on your spreadsheet to do the maths.

Example: Planet Alpha is at grid 137, planet Beta is at 145, so distance is 1-1 = 0 on the x axis, 4-3 = 1 on the y axis and 7-5= 2 on the z axis.

Square them, 0, 1, 4, add them up, 5, take the square root, 2.236... and it is a Jump 2 between these two worlds.

In practice you don't have to get your calculator out and do hundreds of sums, as anything one square over, one along and one up or down or less turns out to be jump 1; 2 squares difference in just one or two of the axes jump 2, and 2 squares difference in two and one in the other is jump 3.

On the example map I have marked all the jump 1 routes in magenta, some of the jump 2 routes in blue and a couple of jump 3 routes in yellow. Putting in all the routes will make the map an utter mess of lines, but make sure each has at least one connection.

Go on doing this until you have a web of connections joining every planet and you have an idea of how planets cluster and which are comparatively isolated, though such worlds may be easily accessible from neighbouring sectors. If players want to go off these lines, fine, they will have to get their calculators out and see if they can do it.

Where is my sector?

Earth is at the centre of Known space and occupies the far corner of the eight central sectors. Your sector's 0,0,0 square will be some multiple of 10 parsecs spinward, trailing, coreward, rimward, north or south of Earth. The first four directions will be familiar enough to old Traveller hands, north and south refer to being 'above' or 'below' the basic galactic plane. The example map, Aquila Sector is 0 parsecs spinward, 10 parsecs rimward and 0 parsecs north of Earth.

On the diagram below the eight core sectors are in blue and Aquila Sector is marked in yellow, with the 000 point marked as a spot in one corner.

Didn't you say something about distance from Earth affecting population?

Yup (see last post). Now you know where Earth is relative to your sectors 000 point (0, -10, 0 for the Aquila Sector) you could work out the exact distance for each planet in it, but that being a ball-ache, you could use a rule of thumb and say everything left, right, above or below a certain line will have a certain pop mod. In the case of the Aquila Sector I deem everything one the left half of the map up to column 4 to be close enough to Earth to merit a -2 pop modifer, so pop is rolled on 2d6-4, everything in column 5 or above a -3, so pop is rolled on 2d6-5.

The right half of the map will have plenty of sparsely inhabited or uninhabited systems, places with nothing more than a few dozen people eking a living on the frontier, making up a scientific expedition or perhaps a military unit left as a 'place marker' until their home nation can get enough people together to make up a proper colonising expedition. Some places will be a name and a number on a star chart somewhere, visited briefly by a scoutship years ago to count how many planets they had and rarely visited since, if ever.

The real edge of Known Space is another 10-15 parsecs out, with places ever more vaguely mapped and more systems not visited at all. Anything could be out there, anything... That lost colony of space Nazis you hear about it starport bars, that interstellar equivalent of the Donner expedition, stranded on an airless moon eating each other, an asteroid made of gold, a monastery of psionic Buddhist monks, real live bug eyed monsters with tentacles and everything...

Filling in the details

Don't. Start with one planet, maybe roll up the planets within one jump in case the players decide (or have to) skip town. The players might want to know where the highest tech place is they can go to and stock up on gear – tell them a random blank one some way off and dice it up when they get there. Ship's Star Atlases are generally an out of date mess (see Scouts below) and further out from Earth you get the sparser the data gets. The only reliable info will be the actual location of the stars themselves. Some crackpots claim they have seen wandering stars and that the Russians/Americans/Chinese/Freemasons/Secret Cabal of Lizard Overlords have deliberately introduced falsified data on that to hide secret systems and lead enemies into jumping into interstellar space light years from anywhere.


There is no unified scout service in Known Space. Each large nation and alliance on Earth and the well established independent colonies has their own, and private companies and freelancers operate as well. With colonies springing up, amalgamating, splitting and fizzling out all over the place much of the work of the national scout services is surveying, visiting known worlds and seeing what is going on, and as couriers maintaining contact with colonies set up by their home nation. Exploration still goes on, with scout companies sending ships hither and yon gathering data and selling it to the highest bidder, all hoping to strike it rich by finding a new Earth and selling it's location and resource data to any nation willing to pay for getting a head start on its exploitation and colonisation.

Next week - the Known Worlds Wiki, and, hopefully, an adventure.


  1. You said it was -1 population for every 5 full parsecs from Earth. So every star in Sol Sector (the sector containing Earth) has a population modifier of 0. Aquila Sector should be at -1 for columns 0 through to 4 and -2 for everything left of that. Unless we go with the top side of the map being Coreward (which is traditional) then replace columns with rows in the above example.

  2. No, Sol lies at the corner of eight sectors, rather than the middle of its own sector (see the little boxy thing about half way down the post), click on the pic to blow it up.

    I quoted the pop mods as including the -2 you always put on the 2d6 roll in Classic Traveller - yup that is confusing, I'll change it.

  3. Surely we would know the number and orbits of planets for each system? Consider what we've done with Kepler already, and other various planet-finding programs and satellites that we will launch in the next hundred years. I can't imagine that we won't know most of the planets and many of the moons within 20 parsecs well before 2300.

    1. Quite possibly, but it's more fun to say not and have players warp into systems not knowing quite what to expect, and to have secret planets and whatnot.

      Spotting a star system nowadays takes a big, big telescope and lots of obs time and a big computer and even then you are probably missing most of the planets. I don't know whether any of the ones found so far have been double checked by independent observers, but we might have some of the data wrong. So, lets say in 2300 you can map a starsystem from a good way off, but it's done by specialist ships run by big governments who spend a moth or more scanning the local sector from two or three points and THEY ARE ALL IN IT TOGETHER! (So say the nuts who believe in secret planets anyway, loons who sit up all night drinking too much coffee spying on nearby stars the charts say are planetless looking for teeny tiny wobbles with cheapo equipment they made out of tinfoil, just like their hats).