Map exchange string format

This is a technical description of the map exchange string format, used to share map generating configurations with other users.

Factorio line wraps the entire map exchange string after 55 characters during export, but ignores all whitespace during import. The outer layer of the map exchange string format includes three angle brackets on either side: ">>>" and "<<<", which must be present for Factorio to accept the string. Between those two tokens is the map exchange data, encoded using base 64 as defined by RFC 4648 (or 3548, 2535, 2045, 1421, et al).

This document will use the terms "int" to refer to 4 byte numbers and "short" to refer to 2 byte numbers. All numerical values are stored in unsigned little-endian format. "boolean" is a single byte that represents true if equal to 1, otherwise it is equal to false. "string"s are Pascal-style int length prefixed strings. The format described below is valid at least for Factorio 0.14.x, older versions may use a different encoding scheme.

Factorio 0.14 and Beyond

This is the base map exchange string format for all Factorio versions 0.14.x and greater.

Type	Description
short[4]	The version string of Factorio that generated this string, used to determine encoding format.
byte[*]	Map Gen Settings. Variable length. See linked section for information on how to parse.
byte[*]	0.15.x Map Settings. If present, this chunk consists of the remainder of the data (minus the checksum).
int	CRC32 checksum of all preceding data, as defined by ANSI X3.66 / FIPS 71 / ITU-T V.42 (the same one used by zlib, ethernet, etc.)

Map Gen Settings

This format is very similar to, but not identical to, MapGenSettings - it is missing both the "terrain_segmentation" and "shift" fields.

For the purpose of the "autoplace_controls" field, a dictionary is an array-like structure, where the number of dictionary entries are encoded at the beginning of the dictionary as an integer (int). Following is a sequence of (key, value) pairs, with the specified data types - e.g. a dictionary[string, int] would consist of a sequence of (string, int) pairs.

Type	LUA key	Description
byte		Water frequency.
byte	water	Water size.
dict<string, byte[3]>	autoplace_controls	An dictionary of Autoplace Controls, with string keys, where the key represents the ore name. Factorio doesn’t care what order this dictionary is in, but it always alphabetizes during export. Vanilla has seven resources: coal, copper-ore, crude-oil, enemy-base, iron-ore, stone, and uranium-ore. Unknown ores are ignored and missing ores are set to their defaults.
int	seed	Map seed.
int	width	Map width.
int	height	Map height.
byte	starting_area	Starting area size.
boolean	peaceful_mode	Peaceful mode. Enabled if set to 1, disabled otherwise.

0.15 Map Settings

All of the following data fields (until noted at the end) have a special encapsulation format. Preceding each value is a single byte that states whether or not the value is present. If the byte is equal to zero, then the field value is not present. Otherwise, then the field's value follows. In this section, the data type "double" refers to the 64-bit floating point format described by IEEE 754.

In the LUA structure, this information is stored in the "game.map_settings" table, which is created by the "MapSettings" prototype. Each section in the table below represents a nested sub-table in "map-settings", where the LUA key listed is the key of the table, and all subsequent fields are part of the sub-table. See data/base/prototypes/map-settings.lua for a description of all attributes.

Fields marked with a check (✓) in the "GUI" column are configurable in the new game map generator GUI.

Type	GUI	LUA key	Description
*	✓	pollution	Pollution
boolean	✓	enabled	Pollution enabled.
double	✓	diffusion_ratio	The amount of pollution that is diffused into neighboring chunk per second.
double		min_to_diffuse	This many PUs must be on the chunk to start diffusing.
double	✓	ageing	[Modifier of] the pollution eaten by a chunks tiles.
double		expected_max_per_chunk	Anything bigger than this is visualised as this value.
double		min_to_show_per_chunk	Anything lower than this (but > 0) is visualised as this value.
double	✓	min_pollution_to_damage_trees	Any pollution above this amount starts to damage trees.
double		pollution_with_max_forest_damage	???
double		pollution_per_tree_damage	???
double	✓	pollution_restored_per_tree_damage	The amount of pollution absorbed by a tree when it is damaged by pollution.
double		max_pollution_to_restore_trees	???
*		steering.default	Steering (Default)
double		???	???
double		???	???
double		separation_force	???
boolean		force_unit_fuzzy_goto_behavior	???
*		steering.moving	Steering (Moving)
double		???	???
double		???	???
double		separation_force	???
boolean		force_unit_fuzzy_goto_behavior	???
*	✓	enemy_evolution	Evolution
boolean	✓	enabled	Evolution enabled.
double	✓	time_factor	Percent increase in the evolve factor for every second.
double	✓	destroy_factor	Percent increase in the evolve factor for every destroyed spawner.
double	✓	pollution_factor	Percent increase in the evolve factor for every 1000 PU [produced].
*	✓	enemy_expansion	Enemy Expansion
boolean	✓	enabled	Enemy expansion enabled.
int	✓	max_expansion_distance	Distance in chunks from the furthest base around.
int		friendly_base_influence_radius	???
int		enemy_building_influence_radius	???
double		building_coefficient	Expansion algorithm. See LUA file for details.
double		other_base_coefficient
double		neighbouring_chunk_coefficient
double		neighbouring_base_chunk_coefficient
double		max_colliding_tiles_coefficient	A chunk has to have at most this much percent unbuildable tiles for it to be considered a candidate.
int	✓	settler_group_min_size	Size of the group that goes to build new base (in game this is multiplied by the evolution factor).
int	✓	settler_group_max_size
int	✓	min_expansion_cooldown	Minimum cooldown.
int	✓	max_expansion_cooldown	Maximum cooldown.
*		unit_group	Unit Group
int		min_group_gathering_time	???
int		max_group_gathering_time	???
int		max_wait_time_for_late_members	???
double		max_group_radius	???
double		min_group_radius	???
double		max_member_speedup_when_behind	???
double		max_member_slowdown_when_ahead	???
double		max_group_slowdown_factor	???
double		max_group_member_fallback_factor	???
double		member_disown_distance	???
int		tick_tolerance_when_member_arrives	???
int		max_gathering_unit_groups	???
int		max_unit_group_size	???
*		path_finder	Path Finder
int		fwd2bwd_ratio	???
double		goal_pressure_ratio	???
bool		use_path_cache	???
double		max_steps_worked_per_tick	???
int		short_cache_size	???
int		long_cache_size	???
double		short_cache_min_cacheable_distance	???
int		short_cache_min_algo_steps_to_cache	???
double		long_cache_min_cacheable_distance	???
int		cache_max_connect_to_cache_steps_multiplier	???
double		cache_accept_path_start_distance_ratio	???
double		cache_accept_path_end_distance_ratio	???
double		negative_cache_accept_path_start_distance_ratio	???
double		negative_cache_accept_path_end_distance_ratio	???
double		cache_path_start_distance_rating_multiplier	???
double		cache_path_end_distance_rating_multiplier	???
double		stale_enemy_with_same_destination_collision_penalty	???
double		ignore_moving_enemy_collision_distance	???
double		enemy_with_different_destination_collision_penalty	???
double		general_entity_collision_penalty	???
double		general_entity_subsequent_collision_penalty	???
int		max_clients_to_accept_any_new_request	???
int		max_clients_to_accept_short_new_request	???
int		direct_distance_to_consider_short_request	???
int		short_request_max_steps	???
double		short_request_ratio	???
int		min_steps_to_check_path_find_termination	???
double		start_to_goal_cost_multiplier_to_terminate_path_find	???
Note: The following fields do not use the special encapsulation method.
byte[4]		. (root)	Other
int		max_failed_behavior_count	???
Type	GUI	LUA key	Description

Difficulty Settings

This information is instead stored in the LUA structure at game.difficulty_settings, which is prototyped by DifficultySettings. These fields do not use the special encapsulation method noted above.

Type	GUI	LUA key	Description
byte[10]	✓	difficulty_settings	Difficulty Settings
byte	✓	recipe_difficulty	Recipe difficulty. 0 for Normal, 1 for Expensive.
byte	✓	technology_difficulty	Technology difficulty. 0 for Normal, 1 for Expensive.
double	✓	technology_price_multiplier	Technology price multiplier.

Autoplace Control

See the page on world generation for more information on frequency, size, and richness.

string	Ore name.
byte	Ore frequency.
byte	Ore size.
byte	Ore richness.

Map Gen Size

These are the values used for the frequencies, sizes, and richnesses of ores, water, and the starting area size. None is a valid value for all three options.

0	None / None /None
1	Very Low / Small / Poor
2	Low / Small / Poor
3	Normal / Medium / Regular
4	High / Big / Good
5	Very High / Big / Good

Each of the values in a triplet (such as "low", "small", and "poor") are synonymous.