Random map scenarios

[RM]

LDiCesare:

How smooth the winds will be depends on how smooth the wind generating function will be. I think a sine function with a small random disturbance should be smooth enough. And if it is not, and interpolation is necessary, at least the interpolation is done only once.

I am thinking of the possible use of winds in the actual game as well as world generation. A ship moving from Spain to the Caribbean by sail should go faster than it will go in the opposite direction, for example. That would require interpolation during gameplay unless all squares already has a wind of their own, and unnecessary computations during gameplay will slow the game down. Perhaps this is a bit off topic for world generation, but I believe it is better to consider this problem/possibility before it arises.

As a side note about WWEWW winds, it is possible with a high pressure very close to a low pressure creating such patterns. But I guess winds involved have to be weak in order for it to be realistic.


Lord God Jinnai:

The ocean filling idea could work, depending on how common land below sea level that is not sea is. It is very rare, except in Netherlands.

Another idea for creating lakes, is to create them at the same time as rivers. Select areas with high altitude and moisture as starting points for a river, and let the river always move to the lowest adjacent square. If there are no adjacent square that is lower than the current square, then create a lake on the current square. Let the river continue from the lake to the lowest adjacent square.

[Lord God Jinnai]

Lands below sea level exist in every continent except antartica, so i think they are common enough to put in, several are quite large, such as the rift valley in Africa where a new plate is forming.

[Mark_Everson]

Thanks, RM, for the more detailed proposal. I suspect Gary would like yet more details before coding, like what exactly is the "nice formula using air humidity, altitude and distance to poles and equator". But every day its getting more in the direction of a useable model. Thanks for the comments everyone!

[Simon Loverix]

LGJ:
Wetlands and lakes are generated separately, but only if a lake is adjacent to sea it becomes a wetland.
Erosion should be used when generating the height, terrain, etc. Especially if we are going to use tectonics. The river starting points used there can be used for the final rivers also.
A major city area is rather similar to a desert area considering vegetation, but the temperature rise is important for generating disasters.


RM:
The moisture takes into account latitude, height, climate zone, nearby rivers, ocean or sea and wind and water currents. It is in a step-by-step format and not in a formula because all those influences are themselves only generated in steps, they are not all available at once.

Wind and water currents are fairly complicated to generate, since they form one big system adapted to itself, so in fact you can't place them one by one if you want to be correct. As is said above, it is best to depart from certain latitudes (the roaring forties fe) that have a uniform direction for the entire planet and then make deviations. In fact, it is not that bad if we generate them rather randomly if we can't easily find a simple pattern.

Winds were indeed intended to stay the same for the whole game, except in the case of a major climatic disturbance, where they would be regenerated from scratch.
Winds per square could be possible if you can find a way to backtrack their effects. Since winds influence moisture, there should be a change when they are deleted and regenerated anew.
The effects of the currents as I described them are quite significant, so better don't put in too much of them. It was my aim to be able to use them for custom scenario's, where you want a certain area to be desert. If there is no reason for the ecology model that it should be desert, it will be fertile grassland soon enough. So you'd better place a dry wind.

[RM]

Mark_Everson:

OK, if you want a formula, here is one:
Moisture = altitude*a + air_humidity * b + distance_from_the_equator * c,
where a,b and c are constants.
But I think the only way to get a function that get the wanted result, is to try different functions and see which works best. Too many details may distract from what is important.

Simon_Loverix:

The way I see it is that there are two ways to generate wind patterns.

One way is to take a brief look at a wind map for Earth, and try to estimate a rough formula ( i.e. a sine function with a small random disturbance ) for the winds, and then use that formula.

The second way is to try to construct a physical model for winds, generate a few random(?) winds, and then try to make it fit together, perhaps by using an iterated procedure, like a numerical solution to a differential equation.

It is clear that it is more difficult to take the second way, and not even certain to get better results. That is why I would recommend the first method. If you can formulate a procedure using the the second way, it is worth a try, but noone has suggested any such algorithm yet.

And now to answer some of the more detailed objections to my proposal:

"Wind and water currents are fairly complicated to generate"

The generation will not be more complicated than we make it. I think a goal should be to make as simple algorithm as possible, while still getting good results.

"As is said above, it is best to depart from certain latitudes (the roaring forties fe) that have a uniform direction for the entire planet and then make deviations"

I think you will find that a sine pattern scaled correctly will give the correct direction of wind for those latitudes that are fairly uniform. And for latitudes where the winds are often unpredictable, it will give winds that are close to zero (which would be the average wind). But I agree that some randomness should be taken into account. (And mountains, if we can find an easy enough way to do it).

"It was my aim to be able to use them for custom scenario's, where you want a certain area to be desert. If there is no reason for the ecology model that it should be desert, it will be fertile grassland soon enough. So you'd better place a dry wind."

With my suggestions, you can still make sure winds face the directions you want, you just have to do it square by square. At least until there is a good map editor. Besides, I think reevalution of moisture should not be done very often, since things like that do not usually change over night, and it will probably involve costly calculations to evaluate it, regardless of which of our methods are chosen.

[LDiCesare]

OK, if you want a formula, here is one:
Moisture = altitude*a + air_humidity * b + distance_from_the_equator * c,
where a,b and c are constants.

That is precisely the values of a,b,c, or at least a relative value that we need. As long as this is a mathematical model with no randomness, it can be tested on paper. Having no idea what the values should be like, the coder may come up with silly default values and never be able to get them right. We need rough starting values. You don't have any idea how much tuning values is long and difficult. With every change in the military code, I am afraid the cost values I carefeully balanced get totally changed because one unit will become too string for its cost, for instance. I iterated thousands of automated fights and could get short results for 1000 fights when I checked the costs of units. Checking 1000 maps is not that fast, but that would be needed if we start from scratch.
Even if we delivered a program that generates moisture correctly, there are many other factors, like wind, size of the world, etc., which makes lots of variables to tune. If you could provide some starting figures, it would really be very useful.

[LDiCesare]

Bump

(bump)
See also that thread: http://apolyton.net/forums/showthrea...threadid=30811

[Gary Thomas]

Bump

This is another project dear to my heart, which I had partly implemented.

Cheers and PF