Preprocessing the exported data

May 28, 2026 ยท View on GitHub

Prerequisites and assumptions

What is the Preprocessor?

The Mappalachia Preprocessor is a C# .NET CLI tool responsible for assembling and populating the database. It takes in the exported CSVs from XEdit and transforms and combines the data into its final form. It also performs validation against both the database and the existing image assets.

How to use the Preprocessor

Before running, create the Utilities\ folder at the root of the repository, and place sqlite3.exe into it. This can be found at the SQLite downloads page, under precombiled binaries for Windows.

Find the Preprocessor project inside the main Mappalachia solution at Mappalachia.sln, then build and start the Preprocessor project.
If the database does not exist, it will automatically generate the database and perform data and image asset validation.
If the database already exists, you will have the option to re-build it, or just run validation options.

The Preprocessor will ask you to confirm the current version of Fallout 76. It will fetch this from Fallout76.exe if you have it installed in the default Steam location. However, it is recommended to confirm this value in-game too, as the values are commonly different.
In the event they are different, the in-game value should be used.

The outputted database will be placed at Assets\data\mappalachia.db.

Upon completion, the Preprocessor will generate the file BuildOutputs\Database_Summary.txt. This file is version controlled in git, and should be reviewed for changes whenever a new game update is released. Any unusual values or changes may indicate errors.
Similarly, it will generate BuildOutputs\Discarded_Cells.csv. This lists cells which were present in the ESM export, but were not kept in the database. This should be reviewed to ensure no cells were incorrectly discarded.

For potential errors which may arise here, see also: Deployment troubleshooting

Validation

The preprocessor also provides validation functionality, of both the database itself, and the existing image assets. These are automatically run when building the database, or may optionally be run alone.

If errors are found in either step they are outputted to the console at the end. The errors are also written to the file BuildOutputs\Errors.txt. These must be addressed before continuing.

Next steps

Now the database has been assembled and validated, you can optionally extract map icons, render map backgrounds, or move to development of the GUI itself.