By Andrew Brown

http://github.com/brownan/Minecraft-Overviewer

Generates large resolution images of a Minecraft map.

In short, this program reads in Minecraft world files and renders very large resolution images. It performs a similar function to the existing Minecraft Cartographer program but with a slightly different goal in mind: to generate large resolution images such that one can zoom in and see details.

• Renders large resolution images of your world, such that you can zoom in and see details
• Outputs a Google Map powered interface that is memory efficient, both in generating and viewing.
• Renders efficiently in parallel, using as many simultaneous processes as you want!
• Utilizes 2 levels of caching to speed up subsequent renderings of your world.
• Throw the output directory up on a web server to share your Minecraft world with everyone!

This program requires:

• Python 2.6 or 2.7 <http://python.org/download/>
• PIL (Python Imaging Library) <http://www.pythonware.com/products/pil/>
• Numpy <http://scipy.org/Download>

I develop and test this on Linux, but need help testing it on Windows and Mac. If something doesn't work, let me know.

Before you dive into using this, just be aware that, for large maps, there is a lot of data to parse through and process. If your world is very large, expect the initial render to take at least an hour, possibly more. (Since minecraft maps are practically infinite, the maximum time this could take is also infinite!)

If you press ctrl-C, it will stop. The next run will pick up where it left off.

Once your initial render is done, subsequent renderings will be MUCH faster due to all the caching that happens behind the scenes. Just use the same output directory and it will only update the tiles it needs to.

There are probably some other minor glitches along the way, hopefully they will be fixed soon. See the Bugs section below.

To generate a set of Google Map tiles, use the gmap.py script like this:

python gmap.py <Path to World> <Output Directory>

The output directory will be created if it doesn't exist. This will generate a set of image tiles for your world in the directory you choose. When it's done, you will find an index.html file in the same directory that you can use to view it.

Adding the "-p" option will utilize more cores during processing. This can speed up rendering quite a bit. The default is set to the same number of cores in your computer, but you can adjust it.

Example to run 5 worker processes in parallel:

python gmap.py -p 5 <Path to World> <Output Directory>

The -z option will set the zoom level manually. Without this option, the Overviewer will detect the smallest number of zoom levels needed to render your entire map.

Maybe that's too much though, or maybe you have some outlier chunks that are very far off making your map too large to render. That's where this option comes in handy.

This will render your map with 7 zoom levels:

python gmap.py -z 7 <Path to World> <Output Directory>

The zoom level specifies the number of tiles at the highest zoom level. A zoom level of z will generate up to 4^z tiles (2^z by 2^z in a square). This means each additional zoom level covers 4 times as much area as the last one. Tiles with no content will not be rendered, but they still take a small amount of time to process.

The output is two things: an index.html file, and a directory hierarchy full of images. To view your world, simply open index.html in a web browser. Internet access is required to load the Google Maps API files, but you otherwise don't need anything else.

You can throw these files up to a web server to let others view your map. You do not need a Google Maps API key (as was the case with older versions of the API), so just copying the directory to your web server should suffice.

The Overviewer keeps two levels of cache: it saves each chunk rendered individually along side your chunk files in your saved world directory, and it keeps a hash file along side each tile in your output directory. Using these cache files it will not re-render any image that has not changed.

If you want to clear the cache and re-render everything, run gmap.py with the -d option:

python gmap.py -d <Path to World> <Output Directory>

The next time your map is rendered, it will re-render every chunk. This is useful if you've changed texture packs or want to save disk space, but otherwise not too useful.

This is probably not a good idea for very large worlds, since it will take much longer to render the next time you do so.

Image files taking too much disk space? Try using pngcrush. On Linux and probably Mac, if you have pngcrush installed, this command will go and crush all your images in the given destination. This took the total disk usage of the render for my world from 85M to 67M.

find /path/to/destination -name "*.png" -exec pngcrush {} {}.crush \; -exec mv {}.crush {} \;

If you're on Windows, I've gotten word that this command line snippet works provided pngout is installed and on your path. Note that the % symbols will need to be doubled up if this is in a batch file.

FOR /R c:\path\to\tiles\folder %v IN (*.png) DO pngout %v /y

This program has bugs. They are mostly minor things, I wouldn't have released a completely useless program. However, there are a number of things that I want to fix or improve.

For a current list of issues, visit http://github.com/brownan/Minecraft-Overviewer/issues

Feel free to comment on issues, report new issues, and vote on issues that are important to you, so I can prioritize accordingly.

An incomplete list of things I want to fix soon is:

• Rendering non-cube blocks, such as torches, flowers, mine tracks, fences, doors, and the like. Right now they are either not rendered at all, or rendered as if they were a cube, so it looks funny.
• Add lighting
• Some kind of graphical interface.
• A Windows exe for easier access for Windows users.