RegionScanner

A CLI program to scan Minecraft region files and create Just Enough Resources world-gen.json files (or some other formats) from the results. Tested and works on 1.13-1.18 inclusive. On 1.12 and below works only on vanilla worlds (and if you're on 1.12.2 and below, you should be able to use JER's own profiling feature instead).

Installation

The repo automatically builds binaries for multiple different targets via Github Actions, so unless you're using an obscure platform, you should be able to just grab a build for yours from Releases. Extract the executable from the archive and use.

If you're on Windows and not sure which to pick, you most likely want x86_64-pc-windows-msvc. If you're on a 32bit Windows, i686-pc-windows-msvc.

Usage:

region_scanner --dims <DIMENSION_ID> --path <FOLDER>.

See --help for help. Excerpt:

Options:
  -p, --path <FOLDER>
          The absolute path to the save folder of the world to scan. This is the folder the 'region' folder is in. Example: 'D:\Games\MultiMC\instances\FTB Presents Direwolf20 1.16\v.1.4.1\.minecraft\saves\MyTestWorld'

  -d, --dims <DIMENSION_ID>...
          The dimension IDs to scan in the new format. Examples: 'minecraft:overworld', 'minecraft:the_nether', 'minecraft:the_end', 'jamd:mining'

  -z, --zone <FROM_X> <TO_X> <FROM_Z> <TO_Z>
          The zone to scan in every dimension, in regions, in the format of 'FROM_X,TO_X,FROM_Z,TO_Z' (separated either by commas or spaces). For example, '-1,1,-1,1' is a 2x2 square containing regions (-1,-1), (-1,0), (0,-1) and (0,0). If not provided, tries to scan all regions of each dimension

  -f, --format <FORMAT>
          The format to export to
          
          [default: jer]

          Possible values:
          - jer:      world-gen.json compatible with Just Enough Resources
          - tall-csv: world-gen.csv file in CSV format - a row per each level and per each resource

  -t, --threads <THREADS>
          Number of worker threads to use for scanning dimensions. If set to zero, will be chosen automatically by rayon
          
          [default: 0]

  -o, --only-blocks-above <ONLY_BLOCKS_ABOVE>
          If not none, only blocks with a normalized frequency above this value will be exported. Normalized frequency is the sum of frequencies by level divided by 255 (even in 1.18+ worlds which are higher than that). For example, a value of 0.01 means retain blocks more common that 1 in 100 (which is ~655 such blocks per 255-height chunk). The default value is 1e-7, which is about 26 blocks pre 4096 chunks. Some comparisons: minecraft:emerald_ore is ~3e-6, minecraft:deepslate_emerald_ore (1.18) is ~2e-7, minecraft:ancient_debris is ~2e-5
          
          [default: 1e-7]

      --proto <PROTO>
          How to handle protochunks (chunks with a status other than minecraft:full, meaning they aren't fully generated)
          
          [default: skip]

          Possible values:
          - skip:       Protochunks will be skipped
          - include:    Protochunks will be included in the scan
          - only-proto: *Only* protochunks will be scanned (useful for testing)

Example command: region_scanner.exe --path "D:\Games\MultiMC\instances\FTB Presents Direwolf20 1.16 v.1.4.1\.minecraft\saves\MyTestWorld" --dims minecraft:overworld minecraft:the_nether minecraft:the_end.

Detailed instructions for generating a JER file:

Download the executable from releases and place it wherever you want, preferably in a folder of its own. You'll also want a way to efficiently pregenerate the world, like Chunk Pregenerator.
Make a new world. Pregenerate a large area around the world origin - for example, /pregen start gen radius pregentheworld SQUARE 0 0 66 minecraft:overworld to pregenerate a square a bit bigger than 128 chunks at a side. This will take multiple minutes (the GUI will show progress). If you want to profile multiple dimensions, do the same for each dimension.
After the generation is finished, you can exit the world (and close the client if you want). Open the command line in the folder you placed the executable into and run:

region_scanner.exe --path "<path to your world>" --dims <all the dimensions you want to scan, separated by spaces> --zone -2,2,-2,2

Here we provide the zone to scan in each dimension explicitly, but it's also possible to omit the --zone argument to make it scan all regions it finds. Protochunks (chunks that are marked as not fully generated) will be skipped by default. Also see options and usage examples in the previous section.

Watch the scanning progress. The program currently reports on starting every new region, as well as prints a report for every dimension.
After finishing, the program will create (and overwrite if present) a world-gen.json file in the output folder where you put it. This file goes into the /config folder of your Minecraft instance. After reloading the world, your Just Enough Resources should find it and start showing the Ore Generation tabs for every block that was in the scanned area. Filtering by kind of block is currently not implemented (but see --only-blocks-above, which does a decent job of filtering out junk) - you can filter the JSON manually if needed.

Supported formats

JER

The default export format is a world-gen.json file compatible with Just Enough Resources. Some details change with version, but the overall JSON structure is a list of dicts such as this one:

{
"block": "minecraft:jukebox",
"distrib": "39,0.00000762939453125;40,0;41,0;42,0;43,0;44,0;45,0;46,0;47,0;48,0.00000762939453125;",
"silktouch": false,
"dim": "minecraft:overworld"
},

where the "distrib" key contains the frequency by level. Notably, the levels are always nonnegative - JER does this by offsetting the level by 64 for 1.18+ worlds, so in the distribution for a 1.18 world, level 5 in the distribution string is actually y=-59. The files generated by RegionScanner have some peculiarities:

silktouch is always false, RegionScanner doesn't support determining how an ore should be mined or what the drops are - this info can't be parsed from the world file alone.
distrib mentions all points from the bottom of the world to highest y-level the ore was found on, including zero frequencies. For example, above there's only two levels with jukeboxes founds on them, 39 and 48, yet the distribution mentions all levels between too. This is necessary to produce accurate JER plots, since it seems to just connect the points in order without assuming that unmentioned frequencies are zero.

Note also that some modded dimensions go below the depth limit (e.g. Spectrum's Deeper Down). JER doesn't accept such distributions, and so neither does RegionScanner generate them - these heights are just skipped, and a warning is emitted. See issue #11 for details.

Tall CSV

Useful if you want to later import the worldgen data into some data science suite. The CSV generated looks like this:

dim,block,level,freq
minecraft:overworld,minecraft:brick_stairs,19,0.0000019073486328125

Notably, unlike the JER format, level isn't offset and can be negative in 1.18+ worlds.

RundownRhino / RegionScanner