Merged Lands

merged_lands.exe is a tool for merging land in TES3 mods.

The output of the tool is a plugin called Merged Lands.esp that should go at the end of your load order. Yes, that includes after Merged Objects.esp if you're using TES3Merge.

The plugin contains a merged representation of any LAND, LTEX, and CELL records edited by mods.

How?

1. The tool builds a "reference" landmass by merging all .ESM plugins using a similar algorithm as Morrowind.
2. The tool calculates a "difference" landmass for each mod with respect to the reference landmass.
3. The tool copies the "reference" landmass into a new "merged" landmass.
4. For each "difference" landmass from a plugin, the tool merges it into the "merged" landmass. If mods do not overlap with their changes, the resulting terrain will perfectly match both mods' intended changes. If there is overlap, the tool will attempt to resolve the conflicts in an intelligent manner.
5. The "merged" landmass is checked for seams and repaired if necessary.
6. The "merged" landmass is converted into the TES3 format and saved as a plugin.

Limitations

• The tool does NOT move entities within the cell. This may result in floating or buried objects. This may include grass from any grass mods, or similar landscape detailing.
• The tool does NOT perform magic. If one mod puts a hill in the exact same spot another mod tries to put a valley, the resulting land will likely be less than appealing.

Installation & Usage

1. Create a folder for the tool's executable, e.g. merged_lands_bin.
2. Create a directory in that folder called Conflicts.
3. Place the executable in the merged_lands_bin folder.

You should have a directory tree that looks like the following:

merged_lands_bin\
    merged_lands.exe
    Conflicts\

To run the tool, open a terminal (e.g. cmd) in the merged_lands directory and pass the path to your Morrowind Data Files directory with the --data-files-dir flag.

# Example of running the tool
merged_lands_bin> .\merged_lands.exe --data-files-dir "C:\Program Files (x86)\Steam\steamapps\common\Morrowind\Data Files"

An example configuration for MO2 is shown below.

Outputs

By default, the tool will save the output Merged Lands.esp in the Data Files directory.

This can be changed with the --output-file-dir and --output-file arguments.

Troubleshooting Merges

The tool will save the log file to the --merged-lands-dir. This defaults to ., or "the current directory".

The tool will save images to a folder Conflicts in the --merged-lands-dir.

merged_lands_bin\
    merged_lands.exe
    merged_lands.log   <-- Log file.
    Conflicts\
        ...            <-- Images of conflicts.

A conflict image shows green where changes were merged without any conflicts, whereas yellow means a minor conflict occurred, and red means a major conflict occurred. In addition, the tool creates MERGED map showing the final result.

Note: Each conflict image is created relative to a specific plugin. This makes it easier to understand how the final land differs from the expectation of each plugin.

In addition, the tool can be run with the --add-debug-vertex-colors switch to color the actual LAND records saved in the output file. This feature can help with understanding where a conflict shown in the Conflicts folder actually exists in-game and the severity of it with respect to the world.

Other Configuration

Run the tool with --help to see a full list of supported arguments.

Supporting Patches

The tool will automatically read .mergedlands.toml files from the Data Files directory.

Data Files\
    Cantons_on_the_Global_Map_v1.1.esp
    Cantons_on_the_Global_Map_v1.1.mergedlands.toml

These files are used to control the tool's behavior.

Example 1. Cantons_on_the_Global_Map_v1.1.mergedlands.toml

This patch file would instruct the tool to ignore all changes made by the mod except for those related to world_map_data. Then, for those changes only, the mod would resolve any conflicts with other mods by using the changes from Cantons on the Global Map instead.

version = "0"
meta_type = "Patch"

[height_map]
included = false

[vertex_colors]
included = false

[texture_indices]
included = false

[world_map_data]
conflict_strategy = "Overwrite"

Example 2. BCOM_Suran Expansion.mergedlands.toml

The Beautiful Cities of Morrowind Suran Expansion mod should load after BCoM. It modifies the same land, and we would like to prefer the changes from Suran Expanson over the normal BCoM edits. We can set each field to "Overwrite".

version = "0"
meta_type = "Patch"

[height_map]
conflict_strategy = "Overwrite"

[vertex_colors]
conflict_strategy = "Overwrite"

[texture_indices]
conflict_strategy = "Overwrite"

[world_map_data]
conflict_strategy = "Overwrite"

The example conflict shown above in Troubleshooting Merges is now fixed.

Example 3. Ignoring Changes

If we'd like a mod to load after another mod and not try to merge changes where those mods conflict, we can use the "Ignore" setting. For example, if we knew that some mod would overwrite texture changes from an earlier mod, and we wanted to prevent that, we could do the following:

version = "0"
meta_type = "Patch"

[texture_indices]
conflict_strategy = "Ignore"

Defaults

Each type of LAND record is included = true and conflict_strategy = "Auto" by default. "Auto" allows the tool to determine an "optimal" way to resolve conflicts -- whether that means merging, overwriting, or even ignoring the conflict. You should not write a .mergedlands.toml file until it is known to be necessary.