Many small moons have impossibly high populations

[exoterws]

Observed behaviour

In 2 of the starting systems alone, several small moons have impossibly high populations which always seem to cluster between 400 - 600 million. If you do the math for surface area of a sphere given the stated radius, these figures are extremely improbable.

In Sol, Deimos and Phobos moons around Mars. In Barnard's star, some of the moons around Impression.
These all have radius of like 10 km, and yet the populations are like half a billion. How is this possible? It's like 3 sq m per person for the surface area. Several Jovian moons as well: Thebe, Adrastae, Amalthea - all have populations between like 500-800 million I think despite having also pretty small radius'.

It seems odd that all these similarly sized moons have similarly sized, impossible populations unless you imagine they've tunneled through all the rock. And even then how about a bit more variety in the population? If these values were added manually someone didn't consider the surface area of these moons and how/why so many people would be living in places devoid of any charm and with likely limited economic activity. If they are generated by the game, some coefficients need adjusting and greater randomization applied so not every tiny rocky moon with a population has several hundred million people.

Expected behaviour

Some small moons have high populations, (but probably not that high) and some small moons have low populations.

Steps to reproduce

Launch the game and inspect the moons mentioned above.

My pioneer version (and OS):
Pioneer version 2025-05-01
Linux

[bszlrd]

I've just checked Thebe, and its population is set to 0 in the json, and the editor does not allow editing it either. Could it be some kind of override?

[exoterws]

@bszlrd I have to admit I don't have a fork of this setup to test changes on and I'm not even sure which are the right files to look at. I notice though that there's 00_sol.lua in data/systems, in which no reference to populations is made for thebe, deimos, or phobos etc. And then you have in data/systems/custom 00_sol.json, in which "f0/0" is the population specified for all these places and their bases (which also is curious - how can their be bases if there's no population at all?)

Is the game using the ../00_sol.lua where no populations are specified, instead of the custom/00_sol.json where its zero?

Instead for Barnard's star, data/systems/custom/00_barnard_s_star.json also has no references whatsoever to populations for the rocks around planet Impression. You're suggesting the game generates (in an exaggerated way) huge populations whenever the population is not specified, or specified as zero?

[syonfox]

What about underground bases I would think especially for moon colonies you would build a massive structure underground. I would guess I would consider area / 2 as a more realistic calculation.

possibly

let area
let surface 
let maxbh =  10km // And this theoretical tallest building could probably go even taller than 8,849 meters from https://www.bloomberg.com/news/articles/2012-08-16/is-there-a-limit-to-how-tall-buildings-can-get
let minbh = radius / 2 

integrate surface area from minbh to maxbh. for max population area. 

maybe divide by 50? 

Case study earth:

Bombay population 23 Million in just 438 sq. km

23000000/6328 = 3635 people /km^2

Sphere's surface area at 10km = 1256.637

1256 * 3635 = 4565560

Average range:
The average height of buildings in major Indian cities like Mumbai can range from approximately 50 meters to nearly 200 meters.

so say we can build 10 times that above ground and under ground (2km up and down)

4565560 * 20 = 91311200 = approx 100million. And we are not even considering orbital rings or very high density pod based living.

But yeah it does seem high to have half a billion people on a 10km rock in space.

4188790204786 / 600000000
6981 cubic meter per person if you hallow it out.

100 * 10 * 7 m room per person leaving the surface untouched.

The point is very hard yes but maybe not impossible.

Fallow up question. How could we render city light or something to reflect these high population density planets?

Or make the surface completely covered in a labyrinth of building and sky-ways you have to dodge between instead of craters and valleys

[zonkmachine]

What about underground bases I would think especially for moon colonies you would build a massive structure underground.

This issue concerns a real unbalanced in the game and it's unintentional. You can have underground bases, or even civilizations, but that's another question altogether. I think the forum is an excellent place to bring this up.
Here: https://forum.pioneerspacesim.net/index.php !

[syonfox]

Im sorry, I think I over reacted to the word impossible. I was trying to say its possible. And yeah if I read on he said improbable in the next line.

To address the imbalance in the game how is population calculated? Why is it relevant?
what factors does it influence?

A naive approach is tech level = pop cap per city.

so if a planet has 1 city and is tech level 6 it would have 0.6 million?

Poking around I found this code.

//CityOnPlanet.cpp#598

// Calculate the radius for this city based on the SystemBody's parameters
void CityOnPlanet::CalcCityRadius(const SystemBody *body)
{
	double population = body->GetPopulation();
	double atmo = body->GetAtmosOxidizing();

	for (const CityRadiusDef &radii : reverse_container(m_cityType->sizeDefs)) {
		bool isLast = (&radii == &m_cityType->sizeDefs.front());

		if (population > radii.population && !isLast)
			continue;

		m_cityRadius = radii.baseSize + (atmo * radii.atmoSize) + (m_rand.Double() * radii.randomSize);
		m_cityDensity = radii.density * 0.8;
		break;
	}
}

IM not sure I can make scene of this. It is to do with the city radius calculation

I think the next step is to fallow the body->GetPopulation();

... for reference the debug code in the file works.

todo read the code effecting m_population