Delta Plugin and Groundcoverify

Step #57 in the Just Good Morrowind list

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Benjamin Winger
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Transcoder for managing a form of markup-based minimal Elder Scrolls Plugin files and OMWAddon files and a simple python script which uses Delta Plugin to turn regular groundcover in morrowind plugins into openmw-style groundcover.

Usage Info

Did you find any inaccurate information below? Please let us know by opening an issue on GitLab or joining our Discord!

Data path:
Usage Notes:

Users following a Mod List can proceed onto the Final Steps as these instructions are covered there. Legacy instructions are included below.

Delta Plugin instructions (click to expand/collapse):

Delta Plugin is a command-line program that will merge objects from your mod's plugins. It is strongly recommended that you do not skip this, many mods need merging to happen in order to function as intended.

Download the zip of the latest Package release for your operating system and extract the included binary to the suggested folder path shown above. To run it:

  • First, consult the CFG Generator to ensure your plugin load order is correct.
  • At this point in the modlist you will not yet have delta-merged.omwaddon, deleted_groundcover.omwaddon, and LightFixes.esp. Make sure they are not in your CFG at this point, or the merge will fail. In the future should you wish to regenerate a merged plugin due to load order change, you'll want to omit these as well.
  • On Windows, navigate to the folder you extracted Delta Plugin into and Shift+Right-click the folder to open the context menu. Click Open Powershell window here and type the following command:
    .\delta_plugin.exe merge --skip-cells .\delta-merged.omwaddon
  • On Linux or MacOS, cd to the folder you extracted Delta Plugin into and use the following command:
    ./delta_plugin merge --skip-cells delta-merged.omwaddon

It is very important that you add the --skip-cells argument after merge! Omitting this will cause problems.

It will read the load order defined in your openmw.cfg file and produce a merged plugin (delta-merged.omwaddon) in the location specified in the command. This delta-merged.omwaddon file should be loaded last.

A merged plugin produced by Delta Plugin will auto-clean all dirty records with the exception of Evil GMSTs.

Note that merging large load orders will require a lot of memory (and/or a large page/swap file), you can reduce memory usage by setting the RAYON_NUM_THREADS=1 environment variable.

Please see this page for more resources on the topic of object merging.

NOTE MO2 users read this: make sure to follow your specific "Mod-Organizer To Openmw" way of handling omwaddon, omwscript, files for this.

Groundcoverify instructions (click to expand/collapse):

Please note that while these steps may seem somewhat involved, this tool can yield a decent-sized FPS gain so we urge you to not skip it.

  1. Install Python3 on your system:
    • Windows users can get it from this link on - make sure to select the option Add Python 3.X to PATH during installation!
    • macOS users can get it from this link on
    • Linux users should get python from their distro (you probably already have it)
  2. If you already had Python installed previously:
    • Your version of Python is 3.6 or lower: You need to update Python to the newest version
    • Your version of Python is 3.7 to 3.10: You need to install tomli (python -m pip install tomli in terminal/PowerShell)
    • Your version of Python is 3.11 or higher: You can continue
  3. Download Groundcoverify from this link
  4. Extract it to the provided data path
  5. On Windows, navigate to the folder you installed Groundcoverify into and Shift+Right-click the folder to bring up the context menu. Click Open Powershell window here and use the following command:
    python .\ --verbose --delta-plugin-exe .\delta_plugin.exe
  6. On Linux and macOS, just open your normal terminal application, cd to the directory you installed Groundcoverify into, and use the following command:
    ./ --verbose --delta-plugin-exe ./delta_plugin
  7. When it completes, you should have two plugins, deleted_groundcover.omwaddon and groundcover.omwaddon, and a meshes folder
Content Plugins:
Groundcover Plugin:
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