My map is more crude. It uses all stars within 100 light-years of Sol contained in the Hipparcos catalog.
The 13 "empires" are of equal size, arranged by close packing of spheres (vertexes of a cuboctahedron. Stars whose distance between empire centers are nearly equal are considered to be in the "neutral zone", disputed territory.
@nyrath I have the Hipparcos catalogue incorporated as well. For me the significant work was in removing false positive detections in Gaia DR2 (and there were a lot), then merging and de-duping the set with the other common sets. Your empire-spheres seem to be in various orientations - does this imply that each polity uses its own coordinate frame?
Removing the false positives in Gaia DR2, merging, and de-duping is a process I find intimidating enough to scare me off. So I have been making do with Hipparcos.
No, my empire spheres are all in the same orientation. The map is such a tangled mess of lines so it is hard to tell. Changing orientation would be easy, but not particularly useful.
I want to write simulations where the origin stars send out colony ships, to generate history.
@nyrath I've done that too (origin stars sending out colony ships then a world population growth model, followed by trade simulation), and I need to pick it back up as it's only partly complete. I have a frequent context switch problem.
I never had any good numbers on how to correlate the population growth with industrial infrastructure growth. That is, to the point where the colony would be sending out its own colony and trade ships.
@nyrath For Traveller, incidentally, I'm not sure what the meaning of borders actually is. An entire fleet could move through an enemy controlled system - jump in, refuel in cometary halo, jump out, before light speed propagation delay of knowledge of the fleet's presence even reaches the mainworld.
@nyrath In Traveller one of the first things that is said about the setting and is fundamental to the game is that information cannot travel faster than light, except via jump drive, that combined with a lower limit on the size of a jump drive (for 100 DTon ships) puts some of the concerns of your site into play. In practice for me, though, it usually means that a mainworld might be controlled and defended, but the entire system cannot be.
For an empire, control depends upon communication.
As a vague general rule, figure that the maximum time allowed to send a message from the central capital to a colony on the rim of the empire should be no more than about 12 weeks (about the lag-time of the old Mongol Empire).
@nyrath@sudnadja There's no FTL radar in Stardust but I managed to have borders (porous ones but still) by not only limiting the range of jumps but also making it so that you can only jump again after exiting warp by spending some time in a gravity well. (from 12 hours for the most refractory-optimized drives to more than 2 days for the usual one). And you can't initiate warp in a gravity well equivalent to the one up to the orbit of Neptune or so.
@nyrath@sudnadja So you need to go through frontier systems to get to the enemy's core world. Where they can intercept you along the way. That's why outposts in uninhabited systems are important, they can send an alert that the enemy is coming.
@nyrath@sudnadja The Honor Harrington books started out with ship's jumps creating an FTL gravity signature that could be picked up. They eventually worked out how to use this as a x64C communication mode that revolutionized space warfare.
@sudnadja@nyrath
Oort cloud: Discovered 1950
Traveller game: Published 1977
So really there's no way MM could have accounted for this breaking the fnord out of his world model.
@Hcobb@nyrath I think MM might have even intended that jumps are always mainworld to mainworld, which would also eliminate the system defensibility problem, but later editions of the game and supplements clearly allow for jumping to non-mainworld positions.
@sudnadja@nyrath Handy fudge to deal with a lot of the FTL wormholes in Traveller is to make the jumps from one 1 cm/s^2 gravity shell to another. Sol's shell then extends past Venus while comets are too tiny to hit from another star.
@Robert_Brandt@nyrath I have 1.6 million from DR2, but it's cumbersome to load and work with. I do, however, plot sky charts with it: Here's the path of Borisov (not quite accurate, it was my own orbit determination) - but each background small-point is a Gaia DR2 star.
@sudnadja@nyrath I found doing 521 of the closest was a lot of work, I am working on another book atm 190 pages, companion to Andromeda Dragons, 44 star systems expanded
@RogerBW@nyrath@sudnadja Does this include respecting Visser collapse avoidance constraints or are you assuming the wormholes were balanced during projection ala The Human Reach?
@Sevoris@nyrath@sudnadja The wormhole net started as a 4-dimensional Delaunay triangulation (x, y, z, spectrum) so that links are to nearby and similar stars; then I pruned it aggressively to make the map a bit more interesting while still leaving every star reachable.
@Robert_Brandt@Sevoris@nyrath@sudnadja Stable, stationary-ish; the positions depend on both stars' masses and positions so they change a bit over the long term.
(Then I started from Sol and ran a growth rate based builder, how long until a colony is big/rich enough to set out colonising ships of its own. So an G5 will end out ships much sooner than a M0.)
@nyrath@notasnark Though admittedly niche, the nice thing about a 3d star map is it allows for you to plot the sky from an arbitrary world within the setting (here, for example, Aurore with correctly-positioned stars, camera pointed toward Orion). That can help with setting immersion.
Don't get me wrong. A 2d star map is perfect... for a TTRPG.
But I am dealing more with creating a simulation. That has to be modeled in 3d or the star distances are unreliable. Since the computer program is doing all the work I could care less if it uses nasty mathematics.
@nyrath@sudnadja
IF your FTL is based on finite routes between stars (wormholes, gates, jumplanes, &c.) instead of a "go-anywhere" drive, you get the lovely perk of being able to use subway-style topological maps. They're clearly (pun intended) easier to read. 😁
Here is a subway style star map I made about a decade and a half ago, using a Python app I wrote, feeding the output into the amazing yEd drawing package.
@nyrath
Heh. I knew you know! I like the subway maps for getting a strategic feel, but nothing beats the awesome looks of a 3D star map. I wish there were more programs out there that let people work with 3D star plots.
I'm especially interested in how @sudnadja is doing all this fancy stuff in Mathematica...
The golden feature of yEd is the "auto-arrange". It will take your tangled mess of a map and automatically untangle it. It has several types of auto-arrange, each with parameters you can tweek.
I too am interested in how @sudnadja is working his Mathematica magic, but I want to learn the basics first myself. I've fooled around with it but nothing serious.
@nyrath@codrusofathens@sudnadja I’ll have to get around to githubbing it all at some point. Like many hobbyists though much of my code is written in a way that only I really understand and it needs to be cleaned up. But I’ll get to it
@nyrath@sudnadja
It seems like a very, very powerful set of tools. Also a very, very expensive set, but for the moment, I'm a university student, so I can use the school's installation...
@codrusofathens@nyrath@sudnadja the student or hobbyist licenses aren’t that expensive and you can use the kernel install on raspberry pi for free. I have started rewriting a lot of what I do in python and C (and a yet unfinished OpenCL nbody solver) which might be more digestible, but there is a lot of built in utility in Mathematica that is hard to get away from
If you have a Windows machine and $35, AstroSynthesis is a great star mapping package for TTRPG or scifi novel writers. https://nbos.com/products/astrosynthesis
@sudnadja@nyrath Alas, my world is a 170x170x230ly ellipsoid where FTL works for Reasons™️. Which is too large for that kind of program and a large chunk of it is outside of surveys.
According to my calculations, there are ~110 thousand stars in the Oval (said ellipsoid). Got it by calculating the volume of that region, then multiplying by the star density per cubic lightyear in our area of the Milky Way (0.004).
Far too much for a node map so my map is just flat-colored blobs.
@nyrath this is super useful. I've been using space engine and math to plot stuff like this for stories, games, and just for fun. Because interstellar navigation and rout plotting at relativistic speeds is fun for the whole family.
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