Upgrade Minecraft Maps: New Biomes & Seamless Transitions

The south-western portion of the map is highlighted, allowing for easy identification of the smoothed seam in subsequent steps.

Regardless of the map you choose, it is crucial to avoid loading or exploring it from the older Minecraft version within the newer version before completing the initial MCMerge phase. Doing so could introduce irreversible errors into your world.

Furthermore, prior to continuing, ensure a backup of your chosen map is created. While we have experienced no issues with MCMerge or other world editing tools, a backup provides essential protection.

Acquiring MCMerge

The latest version of MCMerge is available for download from the official MCMerge discussion thread on the Minecraft forums.

Two distinct versions are offered: Python code compatible with Mac OS X, Linux, and other operating systems, and a pre-compiled version for Windows.

The Python version necessitates the installation of Python and several dependencies, as detailed in the accompanying readme file.

Conversely, the Windows version only requires the Microsoft Visual C++ 2008 Redistributable Package (x86) if it isn't already present on your system.

Version Specifics

For the purposes of this guide, we will focus on the Windows version.

Users utilizing the Python version should substitute "mcmerge.exe" with "python mcmerge.py" in all subsequent commands.

All command-line switches and modifiers will remain consistent regardless of the version used.

Preparing Your World

Before continuing, copy the save folder of the Minecraft world you intend to modify into the /MCMerge/ directory.

For example, if your world is named "Funland", a new directory structure should be created: /MCMerge/Funland/.

Initiating the First MCMerge Operation

Having positioned the save directory within the /worlds/ folder, the next step involves executing the initial pass. During this phase, MCMerge will delineate the existing map's perimeter, identifying chunks situated directly at the boundary of the explored area.

To initiate this tracing process, utilize the following command from the /MCMerge/ directory through the command line, substituting "world" with the actual name of your world save.

mcmerge.exe trace "world"

The tracing operation is generally swift, even when dealing with extensive worlds, and will produce output similar to the following.

Acquiring the current world contour...

Tracing the world’s perimeter...

Documenting world contour information...

World contour identification is now finished.

MCMerge now possesses the necessary data. Verification of successful completion can be achieved by inspecting your world directory; a new folder designated "##MCEDIT.TEMP##" and a file named "contour.dat" should be present.

Should the command encounter errors or fail to generate these files, executing it with administrator privileges may be required.

Generating Updated Chunk Data

Following the completion of the contouring process, the subsequent action involves loading your Minecraft world within the latest Minecraft iteration. It is crucial to emphasize this point; loading the world with an older version will prevent the incorporation of new biomes generated by the updated terrain generator.

This would result in the retention of the original biome data, effectively nullifying the entire process and necessitating a restart.

There are two distinct methods for generating this new chunk data. One option is to actively play the game, navigating in creative mode along the perimeter of your world to load new data.

For smaller maps, such as the one utilized in this tutorial, this approach is entirely feasible.

However, for larger maps, manually exploring the old world border could consume significant time, potentially ranging from hours to days. Furthermore, some players may prefer to avoid exploration to preserve the element of surprise in survival mode.

In such cases, employing the Minecraft Land Generator offers an automated solution for loading map data without requiring in-game exploration.

Should you choose not to explore the entire border or find the Minecraft Land Generator configuration too complex at this time, there is no need for concern.

The contour data created in the previous step remains valid indefinitely, as it accurately defines the boundaries of your original map. You can re-run the merging process as often as needed as you discover areas that do not render correctly.

After the contouring is finished, transfer your world data back into your Minecraft folder and then launch the map using the newest Minecraft version.

Travel around the map's edges until you observe the uneven and visually unappealing seams, similar to those shown in the example render.

Once you have explored the map and generated the new chunk data, you can proceed to the cleanup phase.

Completing the Map Integration

The concluding phase of this procedure involves transferring the saved game file from your Minecraft save directory – after generating the updated data using the latest Minecraft version – back into the /MCMerge/ folder utilized during the process.

Once the map file is updated, execute the following command:

mcmerge.exe merge "world"

Allow the process to run its course. For smaller worlds, completion typically takes only a few minutes. However, significantly larger worlds may require an hour or more. Upon completion, copy the save file from the MCMerge directory back to your Minecraft saves directory and load it. Your world will then be updated, exhibiting considerably smoother transitions between biomes, eliminating the previously noticeable jagged and abrupt changes in terrain.

Recall the starkness of the transitions observed in the earlier rendering? Let's now examine a new rendering of the map data, showcasing the integrated edges.

The result is quite impressive. The smoothness of the transitions is difficult to fully appreciate from a high altitude, so let's descend for a closer, in-game comparison. Here's a location previously marked by a distinct and unsightly stair-step pattern where the forest biome bordered the ocean, and also, within the same view, an abrupt seam between the plains and mountain areas.

In the map corrected by MCMerge, as seen below from a slightly altered angle to highlight the changes, the shoreline is fragmented and varied, and the seam between the plains and mountains is resolved with a river and elevation adjustments along the mountain biome's edge.

What was once a glaring imperfection, suggesting a game malfunction, now appears perfectly natural within the Minecraft environment. Even extensive, linear seams are concealed effectively, maintaining a natural aesthetic.

Below is a screenshot illustrating a location, spanning dozens of chunks, where two biomes previously met along a straight line. While the generated river appears somewhat artificial, given the typically winding nature of Minecraft rivers (and a keen observer might notice its unusual straightness from above), it still presents a more natural appearance than a perfectly defined border between the biomes.

When addressing perfectly straight seams, MCMerge performs a more than adequate job of smoothing and blurring the transitions (to the extent that they become noticeable only when viewed from the air or in a rendering). With more organic and meandering map edges, the correction is virtually imperceptible.

In this tutorial, we utilized the default settings under less-than-ideal conditions (our map featured a combination of sharp, straight edges and winding stair-step edges), yet still achieved excellent results. Running MCMerge on a larger, more organically explored map, and further refining the merging options (refer to the readme file for details on adjusting the fuzzing algorithm, river valley depth, and surrounding cover), can produce merged edges so natural that even the person who created them might struggle to identify their location.

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