Frequently Asked Questions

General Questions

Does the Overviewer work with mod blocks?

The Overviewer will render the world, but none of the blocks added by mods will be visible. Currently, the blocks Overviewer supports are hardcoded, and because there is no official Minecraft modding API as of the time of writing, supporting mod blocks is not trivial.

Can I view Overviewer maps without having an internet connection?

Yes, absolutely. The Overviewer switched away from the Google Maps API and now uses Leaflet. All files which Overviewer needs are included in the output, so even if you have no internet connection, you will still be able to view the map without any issues.

When my map expands, I see remnants of another zoom level.

When your map expands (“Your map seems to have expanded beyond its previous bounds”) you may see tiles at a zoom level that shouldn’t be there, usually around the borders. This is probably not a bug, but is typically caused by copying the map tiles from their render destination to another location (such as a web server).

When you’re copying the rendered map, you need to be sure files that don’t exist in the source are deleted in the destination.

Explanation: When Overviewer re-arranges tiles to make room for another zoom level, it moves some tiles at a particular zoom level and places them at a higher zoom level. The tiles that used to be at that zoom level should no longer exist there, but if you’re copying tiles, there is no mechanism to delete those files at the copy destination.

If that explanation doesn’t make full sense, then just know that you must do one of the following:

  • Render the tiles directly to the destination.
  • Copy the tiles from the render destination in a way that deletes extra files, such as using rsync with --delete.
  • Erase and re-copy the files at the final destination when the map expands. Map expansions double the width and height of the map, so you will eventually hit a map size that is unlikely to need another level.

You’ve added a new feature or changed textures, but it’s not showing up on my map!

Some new features will only show up in newly-rendered areas. Use the --forcerender option to update the entire map. If you have a really large map and don’t want to re-render everything, take a look at the rerenderprob configuration option.

The background color of the map is black, and I don’t like it!

You can change the background color by specifying a new one in the configuration file. See the The Configuration File page for more details.

I downloaded the Windows version but when I double-click it, the window closes real fast.

The Overviewer is a command line program and must be run from a command line. It is necessary to become at least a little familiar with a command line to run The Overviewer (if you have no interest in this, perhaps this isn’t the mapping program for you). A brief guide is provided on the Windows Newbie Guide page.

Unfortunately, A full tutorial of the Windows command line is out of scope for this documentation; consult the almighty Google for tutorials and information on the Windows command line. (If you would like to contribute a short tutorial to these docs, please do!)

Batch files are another easy way to run the Overviewer without messing with command lines, but information on how to do this has also not been written.

On a related note, we also welcome contributions for a graphical interface for the Overviewer.

The Overviewer is eating up all my memory!

We have written The Overviewer with memory efficiency in mind. On even the largest worlds we have at our disposal to test with, it should not be taking more than a gigabyte or two. It varies of course, that number is only an estimate, but most computers with a reasonable amount of RAM should run just fine.

If you are seeing exorbitant memory usage, then it is likely either a bug or a subtly corrupted world. Please file an issue or come talk to us on IRC so we can take a look! See Help.

How can I log The Overviewer’s output to a file?

If you are on a UNIX-like system like MacOSX or Linux, you can use shell redirection to write the output into a file: > renderlog.log 2>&1

What this does is redirect the previous commands standard output to the file “renderlog.log”, and redirect the standard error to the standard output. The file will be overwritten each time you run this command line; to simply append the output to the file, use two greater than signs: >> renderlog.log 2>&1

I’ve deleted some sections of my world, but they still appear in the map.

Okay, so making edits to your world in e.g. worldedit has some caveats, especially regarding deleting sections of your world.

This faq also applies to using the crop option.

Under normal operation with vanilla Minecraft and no external tools fiddling with the world, Overviewer performs correctly, rendering areas that have changed, and everything is good.

Often with servers one user will travel reeeeally far out and cause a lot of extra work for the server and for The Overviewer, so you may be tempted to delete parts of your map. This can cause problems, so read on to learn what you can do about it.

First some explanation: Until recently (Mid May 2012) The Overviewer did not have any facility for detecting parts of the map that should no longer exist. Remember that the map is split into small tiles. When Overviewer starts up, the first thing it does is calculate which tiles should exist and which should be updated. This means it does not check or even look at tiles that should not exist. This means that parts of your world which have been deleted will hang around on your map because Overviewer won’t even look at those tiles and notice they shouldn’t be there. You may even see strange artifacts around the border as tiles that should exist get updated.

Now, with the --check-tiles option, The Overviewer will look for and remove tiles that should no longer exist. So you can render your map once with that option and all those extra tiles will get removed automatically. However, this is only half of the solution. The other half is making sure the tiles along the border are re-rendered, or else it will look like your map is being cut off.

Explanation: The tiles next to the ones that were removed are tiles that should continue to exist, but parts of them have chunks that no longer exist. Those tiles then should be re-rendered to show that. However, since tile updates are triggered by the chunk last-modified timestamp changing, and the chunks that still exist have not been updated, those tiles will not get re-rendered.

The consequence of this is that your map will end up looking cut-off around the new borders that were created by the parts you deleted. You can fix this one of two ways.

  1. You can run a render with --forcerender. This has the unfortunate side-effect of re-rendering everything and doing much more work than is necessary.
  2. Manually navigate the tile directory hierarchy and manually delete tiles along the edge. Then run once again with --check-tiles to re-render the tiles you just deleted. This may not be as bad as it seems. Remember each zoom level divides the world into 4 quadrants: 0, 1, 2, and 3 are the upper left, upper right, lower left, and lower right. It shouldn’t be too hard to navigate it manually to find the parts of the map that need re-generating.
  3. The third non-option is to not worry about it. The problem will fix itself if people explore near there, because that will force that part of the map to update.

My map is zoomed out so far that it looks (almost) blank.

We see this quite a bit, and seems to stem from a bug in the Minecraft terrain generation.

Explanation: Minecraft generates chunks of your world as it needs them. When Overviewer goes to render your map, it looks at how big the world is, and calculates how big the maps needs to be in order to fit it all in. Occasionally, we see that Minecraft has generated a few chunks of the world extremely far away from the main part of the world. These erroneous chunks have most likely not been explored [*] and should not exist.

There are two solutions. The preferred is to delete the offending chunks. Open up your region folder of your world and look at the region file names. They are numbered r.##.##.mcr where ## is a number. The two numbers indicate the coordinates of that region file. Look for region files with coordinates much larger in magnitude than any others. Most likely you will find around 1–3 region files with coordinates much larger than any others. Delete or otherwise remove those files, and re-render your map.

The other option is to use the crop option to tell Overviewer not to render all of your map, but instead to only render the specified region.

As always, if you need assistance, come chat with us on irc.

[*]They could also have been triggered by an accidental teleport where the coordinates were typed in manually.

I want to put manual POI definitions or other parts of my config into a separate file.

This can be achieved by creating a module and then importing it in your config. First, create a file containing your markers definitions. We’ll call it

mymarkers = [{'id':'town', 'x':200, 'y':64, 'z':-400, 'name':'Pillowcastle'},
             {'id':'town', 'x':500, 'y':70, 'z': 100, 'name':'brownotopia' }]

The final step is to import the very basic module you’ve just created into your config. In your config, do the following

import sys
sys.path.append("/wherever/your/manualmarkers/is/") # Replace this with your path to,
                                                    # so python can find it

from manualmarkers import *                         # import our markers

# all the usual config stuff goes here

renders["myrender"] = {
    "title" : "foo",
    "world" : "someworld",
    "manualpois" : mymarkers,                         # IMPORTANT! Variable name from
    # and here goes the list of the filters, etc.

Now you should be all set.