All map generator algorithms have a few common parameters, plus any mapgen-specific options such as noise parameters or threshhold values.

Mapgen parameter source precedence

There are several sources which the map generator may retrieve parameters from. In order from highest precedence to lowest they are:

Hard-coded
Lua mods
map_meta.txt
Game-specific config file
Global config file
Default settings (set in defaultsettings.cpp)
Default object constructor values

List of mapgen parameters

Mapgen name

The name of the map generator algorithm being used. Currently supported:

Mapgen name	Developer responsible	Description
v5	missing info	Description needed
v6	kwolekr, celeron55	The current default map generator. Uses an improved Mapgen v2 algorithm for base terrain; terrain is generated entirely using 2D Perlin noise.
v7	kwolekr	The next generation map generator with an emphasis on generating interesting and playable terrain. Has full support for the internal biome infrastructure and uses a mixture of 2D and both positive and negative 3D noise for terrain.
valleys	missing info	Description needed
carpathian	missing info	Description needed
fractal	missing info	Generates maps based on Mandelbrot fractal series
flat	missing info	Generates completely flat world. Replaces the flat flag in mg_flags. Caves, dungeons, decorations, and biomes need to be explicitly excluded to make a flat and empty world.
singlenode	celeron55	Places only a single node everywhere, namely the one aliased to mapgen_singlenode (by default air). Intended to be used by mods that perform total mapgen takeovers.

example: mg_name = v7

Seed

A 64-bit unsigned integer value. At this time, only the lower 32 bits are currently used for randomization.
example: seed = 1246106421

Water level

The y coordinate at which water starts being placed, for mapgens that do place water.
This is also the position at which blocks are assumed to be underground if no block above is present, and thus is not given sunlight.
example: water_level = 1

Mapgen Limit

Limit of map generation, in nodes, in all 6 directions from (0, 0, 0).

Only mapchunks completely within the mapgen limit are generated.
Value is stored per-world.
type: int min: 0 max: 31000

example : mapgen_limit = 4500

Flags parameter

The flags parameter is a set of booleans indicating whether or not a certain option is enabled. Global flags applying to all map generators are listed in mg_flags. Other map generator-specific flags are shown below.
Like all other config and Lua flag fields, they are represented as a comma-delimited string. E.g. the flag string "trees, caves, flat" would direct the Mapgen to create flat terrain with trees and caves.
An exhaustive list of currently recognized Mapgen flags:

Lua/config flag name	Defaults	Allowed values
mgv5_spflags	caverns	caverns, nocaverns
mgv6_spflags	jungles,biomeblend,mudflow,snowbiomes,trees	jungles, biomeblend, mudflow, snowbiomes, flat, trees, nojungles, nobiomeblend, nomudflow, nosnowbiomes, noflat, notrees
mgv7_spflags	mountains,ridges,nofloatlands,caverns	mountains, ridges, floatlands, caverns, nomountains, noridges, nofloatlands, nocaverns
mgcarpathian_spflags	caverns	caverns, nocaverns
mgflat_spflags	nolakes,nohills	lakes, hills, nolakes, nohills
mgvalleys_spflags	altitude_chill,humid_rivers,vary_river_depth,altitude_dry	altitude_chill, noaltitude_chill, humid_rivers, nohumid_rivers, vary_river_depth, novary_river_depth, altitude_dry, noaltitude_dry

Other fine-tuning parameters are available for each map generator, and can be found in lua_api.md.

Chunk size

The side length (in MapBlocks) of the cubic area that is generated at once. Default is 5; larger values take longer to generate but blocks generate quicker on average and could produce larger, more intricate caves and dungeons.
Don't mess around with this if you don't know what you're doing! This parameter cannot be modified through the Lua API.

This article is incomplete.
Please help expand this article to include more useful information.

Mapgen Parameters

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