Low to Medium detail world map

[Armin]

Hello everyone,

I'm programming an app that uses points on a map as password. In order to have a big enough password space, the maps should be as big as possible. However, not only are high-detailed maps that cover wide areas big, they also take quite a while to render (only tested with my Nexus 4). So what I'm looking for is a world map with less detail, but still enogh information so that you can distinguish between points on the map. The point of my project is to have an easy to remember password.

What I found already is the attached file world.map, it's only 1.33MB in size but too low-detailed. It only contains country borders and some major roads. What I'm looking for is a world map, that has a size of 50-100MB. If it contains cities (let's say all cities with 300.000+ people), that would probably be good enough. If it has a bit of additional information, that's also welcome but it really shouldn't exceed 100MB (ofc, 105MB is fine too). Is there a place where I can find such a map? Or create one myself? If there exist equivalent maps of continents, i.e. Europe, Northamerica, Southaerica, Asia and so on, that's also very welcome.

Thank you :)

Armin

[Emux]

That's an interesting question. I guess you found the map from the relative issue.
Unfortunately I'm not aware of any low detail world map, but I'd like also to learn if anyone else knows something.

Creating a generic world map with specific vector data like coastline, country borders, capitals, main lakes / rivers and roads is more about collecting the related data.
Getting them together and creating the map is not so hard after that.
It's important what accuracy the data have and how to handle the zoom levels in the map file.
e.g. the world coastline is over 500MB in shp file format

--
Emux
Cruiser - Atlas

[Armin]

Yes that's where I got it from. Currently, I use self-created maps from http://extract.bbbike.org/?format=mapsforge-osm.zip
The problem is that it's still high-detail, that means while scrolling/browsing the map it still takes a while until it's loaded.
Plus, I can only cut out 6.500km² parts of the map, when I go to the next zoom-level, it tells me the file will be too big (exceed 100MB).
At least, it keeps my map size low while providing a better passwordspace than the world.map file. So it is a feasible option, and I could
provide multiple of these extracts on my server for potential users to choose from.

But if it is possible to have a map that has the quantities size(MB), size(km²) and details balanced in a (for my use) more balanced out,
that'd be really great. Even if it is only possible for continents, it is way easier to provide ~10 maps of continents on an own server than these
rather small extracts.

Unfortunately, I also do not have any knowledge on how to collect the necessary data, neither how to use them to create a map from them. Any
help with this is highly appreciated. If anywhere in the world maps, that may fulfill these requirements exist, please let me know. Since this is a
project for my bachelor's degree, I don't have unlimited time unfortunately, that's why I prefer to use something that already exists :)

Armin

[Ludwig]

Yes, interesting problem. 

First of all, unfortunately the mapsforge map file generation has a coast line problem, but there is a work-around for it that will generate correct land/sea polyons. See https://groups.google.com/forum/#!searchin/mapsforge-dev/mapsforge$20missing$20water$20tiles/mapsforge-dev/x54kHlyKiBM/fhYryejMvgoJ

So, for a nice world map with water/sea areas you will need to get your head around this first.

As Emux pointed out, the coastlines alone will produce a map file that is enormous, but maybe using ogr2ogr to simplify the coastline geometry will reduce the area enough to make it workable.

To reduce the map data included in the files, the tag-mapping.xml file allows you to define which data will be included in the map file. You could also do some sort of selection on a planet.pbf first to maybe just select place=city. 

As a final note, there are some tricks to reduce the overhead included in a map file, otherwise (as each tile has a certain overhead) alone the number of tiles for the entire planet will result in a very large file. 

Let us know if you plan to go down this route, we are certainly happy to help.

 

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[Armin]

Hello Ludwig,

As I said: I'm a total newbie in these matters. What would be the steps necessary to do that?

[Emux]

If you want you can check here a similar discussion about the creation of a custom map that took place a while ago.