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Author Topic: New understanding of climates and snowlines  (Read 13990 times)

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Offline uci

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New understanding of climates and snowlines
« on: March 29, 2018, 07:50:57 PM »
Below is a short description of landscape settings (climates and snowlines). Please use the "Landscape Settings" dialogue to interact with these settings.

This applies only for newly Simutrans versions!
(r8415+, just nightlies at the moment)

Snowlines are at absolute height levels.

summer snowline = maximum height which is snow-free in mid summer;
winter snowline = maximum height which is snow-free in mid winter;


Example:

water_level = -2
summer_snowline = 10
winter_snowline = 2

and we get the following snow coverage on map:

snow in mid summer starts at height: summer_snowline + 1 = 10+1 = 11;
snow in mid winter starts at height: winter_snowline + 1 = 2+1 = 3;

Climate zones are at absolute height levels.

desert/tropical/mediterranean/temperate/tundra/alpine(rocky) climates = maximum height at which that climate exists;
summer snowline = alpine (rocky) climate;
arctic climate (always covered by snow) = extends above alpine climate;


If two climates have the same value only the first climate is shown on map.

Example:

water_level = -2
desert = -1
tropical_climate = -1
mediterranean_climate = 1
temperate_climate = 1
tundra_climate = 1
alpine_climate = 10


and I get the following climate levels on map:

water (-2)
desert (-1)
tropical (none)
mediterranean climate (0..1)
temperate (none)
tundra (none)
alpine climate (2..10)
arctic climate (11+)

How to apply climates on heightmaps derived from real world data?

Here is an example with almost 60 ground levels and climates applied according to reality.

Pico Cristóbal Colón - a high mountain (5700 m) in northern Colombia, very close to the coast.



I use a heightmap with a height resolution of 100m, prepared for water_level = -28 and height_conversion_factor = 2. Horizontal resolution is 100m, but this is not important here. I want the following climate profile (tile height / altitude / climate):

Code: [Select]
-28 /    0m / water
-27 /  100m / tropic
...
-18 /  1000m / tropic
-17 /  1100m / temperate
...
 -8 /  2000m / temperate
 -7 /  2100m / tundra
...
  2 /  3000m / tundra
  3 /  3100m / alpine
...
 22 /  5000m / alpine - winter snow
 23 /  5100m / arctic - summer snow
...
 29 /  5700m / arctic (max height on map)

So I set:

winter_snowline = 5000/100 + water_level - 1 = 50-28-1 = 21
desert = water_level = -28
tropical_climate = 1000/100 + water_level = 10-28 = -18
mediterranean_climate = tropical_climate = -18
temperate_climate = 2000/100 + water_level = 20-28 = -8
tundra_climate = 3000/100 + water_level = 30-28 = 2
alpine_climate (summer snowline) = 5000/100 + water_level = 50-28 = 22


Play yourself with this heightmap here (2108x1472 pixels). It was derived from high resolution topographic and bathymetric data plus a custom colormap for grayscale levels.
« Last Edit: March 29, 2018, 08:55:43 PM by uci »

Offline Andyh

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Re: New understanding of climates and snowlines
« Reply #1 on: April 14, 2018, 05:10:05 PM »
I'm a little confused.  I just went to the Nightly Builds site, but the current version there is 8387.  Where can I download 8415 referenced in this post?

Offline Ters

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Re: New understanding of climates and snowlines
« Reply #2 on: April 14, 2018, 05:46:22 PM »
Our supplier of nightly build services seems to be having problems. To get changes done in revision after 8387, you'll have to check out the source code and build it yourself (which I consider fairly complicated, unless one is using Linux), or get someone to do it for you.

Offline Andyh

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Re: New understanding of climates and snowlines
« Reply #3 on: April 14, 2018, 11:12:21 PM »
Got it.  Thank you.

Offline prissi

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Re: New understanding of climates and snowlines
« Reply #4 on: April 16, 2018, 07:42:44 AM »
You can get newer windows nightlies at http://www.simutrans-forum.de/nightly/