GURPS Space World Building Issue
 

I am running into something I seriously can't puzzle out here. On Step eight it says "Finally, for any world type other than Asteroid Belt, multiply the result by the square of the world’s diameter (measured in Earth diameters).".

To me this seems to be saying use the decimal generated based on earth being 1. Squaring a decimal... Would give me a smaller decimal wouldn't it? I'm bad at math but I tried to find something on the web to tell me other wise I couldn't. While if the world had been just 1 then that would make a considerably larger change in the final number but... Still not seeming even remotely correct. Exactly what the hell am I supposed to square? Can anyone clear this one portion up for me?

Re: GURPS Space World Building Issue
 

Yes it would. Just go ahead and do it.

Re: GURPS Space World Building Issue
 

The math is correct. That calculation is essentially modifying the population capacity by accounting for the surface area of the planet, which is proportional to the square of the diameter. So a planet of 0.9 Earth diameters will have only 0.81 times as much surface area as Earth, while a planet of 1.2 Earth diameters will have 1.44 times as much.

Basically, the square means that getting farther away from 1 will have a disproportionate effect.

Re: GURPS Space World Building Issue
 

I must have gotten something very wrong in the math. It was going to have the population cap at under 200 million for a planet that was over 5000 miles in diameter. At tl 10. That just seems... Questionable.

Re: GURPS Space World Building Issue
 

We need your numbers. What is the world's affinity, diameter, and TL?

Re: GURPS Space World Building Issue
 

I had actually already gotten rid of them. But... roughly 0.5 diameter, 7 affinity, TL 10, 50% ocean coverage... Aaah. I can't remember most of the other attributes but I plan to start over tomorrow. First thing is I'm going to make that World sheet fillable instead of making ugly text files.

Re: GURPS Space World Building Issue
 

If your affinity is 7 then the base would be 130 million times 20 million or 2.6 billion. After applying the diameter modifier it should have been about 1.2 billion with a 5.000 mile diameter. 5,000 miles isn't .5.

Re: GURPS Space World Building Issue
 

I wanted to shamelessly plug my Starsystem generator which takes care of all the fiddly maths for you:
http://ultima.vsos.ethz.ch/starsystem-gen/
With the source here:
https://github.com/tschoppi/starsystem-gen/

However, it seems that something broke on the server, which I'll have to fix tonight.

Re: GURPS Space World Building Issue
 

Okay then I was right on track up until 130 million then. I broke down at the squaring the planets diameter(in earth diameters). I'm very bad with math. And from the wording I couldn't see how the instructions weren't going to make the number smaller not larger.

And it seems like I screwed up at the diameter too. Which I did find kind of confusing but I had though I managed to muddle my way through.

Re: GURPS Space World Building Issue
 

Well, they were. Say for example that your population base is 2.6 billion. That's how many people Earth could sustain at its TL and affinity score and so on. But say your planet's diameter was half of Earth's. Then it would have only one-fourth the surface area. With the same number of people per square mile, and one-fourth the square miles, you get one-fourth the number of people. And one-fourth of 2.6 billion is 0.65 billion. That's how it's meant to work.

Suppose, on the other hand, that the planet had 1.5x Earth's diameter. That's 2.25x the area. That would give you 5.825 billion. Having a lot more people on a bigger planet seems right, yes? But if a bigger planet has more a smaller planet should have fewer.

Re: GURPS Space World Building Issue
 

Oh wow. I had a serious misconception about the effects of a smaller diameter. I never imagined a half the diameter would give you a quarter of the surface area.

I still think I screwed up in a few areas so Myrion's star system generator should be a big help to me. Though so far I've only figured out how to get the example.py going. From some comments in the issues section I think I may possibly me missing out on a lot. lol

Re: GURPS Space World Building Issue
 

Remember that the surface area of a sphere (technically planets are oblate soheroids, but Space doesn't go there and a sphere is close enough) is

A = 4 × pi × r^2

Thus, area is proportional to the square of radius. I believe Space uses diameter for some reason, instead. But D = 2 × r, which gives

A = 4 × pi × (d / 2)^2
A = 4 × pi × (d^2) / 4
A = pi × d^2

So you can see, even with diameter, area is proportional to the square.

Re: GURPS Space World Building Issue
 

I hope it'll help!

Seems to be up and running on my end now :)

Had a misbehaving program block the Starsystem Generator from running after the last reboot...

Re: GURPS Space World Building Issue
 

Hehe I very much appreciate the effort Humabout but the truth is I have trouble with basic math like working anything with fractions and such. I am not bad at all with understanding the pieces to a puzzle I can grasp but my recall is... Ridiculously unreliable.

I'm sure every math rule I ever learned is floating in there somewhere. But for the most part only a very few of them every resurface and usually not enough of them to handle math that is complex. I do okay when enough of the parts are there to intuit what is what but when I need to remember a rule that isn't obvious in the math in front of me? I'm probably hopeless at that point.

Re: GURPS Space World Building Issue
 

lol Myrion I actually just downloaded it from the source and installed python. The first link just showed me a page telling me I had successfully installed tomcat which I havent as I have no idea what it is. ;)

Re: GURPS Space World Building Issue
 

Yeah, tomcat was misbehaving and blocking the Starsystem Generator... My bad! It's fixed now and the link'll work.

Running it from source is cool too, if you want any help with that, I can try to advise via PM.

Re: GURPS Space World Building Issue
 

A suggestion on the generator for improvement:

Allow giving of the random number seed on the starsystem level(The first page) and if given pass on always the same random numbers based on it to the one or more planetary systems generated and use them as random number seeds on those. Thus the same seed would always generate the same resulting system.

Re: GURPS Space World Building Issue
 

Nifty!

The thing I would really like to be able to do is enter star parameters. Specifically spectral class and luminance, because those are the numbers I mostly have for real-world stars, and the others can largely be derived from them.

(While I'm waiting for Jon Zeigler's new system to be ready…)

Re: GURPS Space World Building Issue
 

Hey Myrion I don't suppose you know anyone who tossed together a nifty Species generator too, eh? lol

Re: GURPS Space World Building Issue
 

Feature requests noted!

I'm actually working on the seed issue, but since we didn't think about it in the very beginning there's some odd problems with it.

Also, I'm glad people like it :)

Re: GURPS Space World Building Issue
 

And Roh, no, I don't. Yet ;)

Re: GURPS Space World Building Issue
 

Hehe Was worth a shot. Not even just because it enables my laziness. But the speed of it. Glorious man. Glorious.

Re: GURPS Space World Building Issue
 

weby, your feature request has been fulfilled :) (I think. My tests aren't as robust / don't cover as much code as I'd like them to, yet.)

Give it a shot!

RogerBW, yours will take a bit longer, but I think I can make it happen.

Re: GURPS Space World Building Issue
 

Yowza, the alien creation algorithm is annoyingly manual...

I've been trying to get it into a program, but it's just SO MANY table lookups.
Plus, a lot of things that depend on outside info.

This might take a lot longer, Roh, sorry.

Re: GURPS Space World Building Issue
 

This is poetry. The motion graphic showing the planetary system is amazing.

Re: GURPS Space World Building Issue
 

Aw, thanks!

Since you looked at it, is the passage of time clear to understand?



Actually, in general: Is the Starsystem Generator easy to use/understand?
If not, where are some problem spots?

Re: GURPS Space World Building Issue
 

If each round of the clock circle represents one earth year, no.

I notice you must be assigning additional orbital parameters beyond semi-major axis and eccentricity. What other parameters do you assign and how are they assigned?

I only used it to generate a few systems, but had no problem doing so.

My only hitch was not being able to find spectral classes, e.g. G2V. This should be the first piece of information given about any star, and it's not provided at all. Maybe that's more of a feature request than a problem.

Again, yours is the best system generator I've seen.

Re: GURPS Space World Building Issue
 

Thankyou for doing this, I can't say how much easier it makes my life.

The only thing that I think it is missing is being able to specify the stars present by effective temperature and seperation and I suspect that this is a feature which is not going to be much in demand.

Re: GURPS Space World Building Issue
 

I do like it a lot, and the system graphics bit is awesome. I would prefer if the entire system could be viewed from a single page (rather than having to click to view different orbiting objects), and having the ability to pause the system graphics and click on a planet to get more information out of it would be great.

Re: GURPS Space World Building Issue
 

The current URL for the Starsystem Generator is

https://ultima.vsos.ethz.ch/starsystem-gen/

That is all.