Earth_osm.mca File Download - Can I Use This to View a World Map?
  • Vote Up0Vote Down ianLianL
    When I first downloaded my selected country map I had no option but to also download the relatively large (approx 70MB)  earth_osm.mca  file 
    I assume that it provides the birdseye world image for the GPS Position Provider but can it also be used somehow as a general reference world map?
    Could someone please direct me to a previous post that tells me more fully about this map file?
    Many thanks
  • 17 Comments sorted by
  • Vote Up0Vote Down tomastomas
    in earth_osm.mca you see country borders and major city names, not sure what do you want to use it for
  • Vote Up0Vote Down OldieOldie
    Mapfactor should know best, what earth_osm.mca is for ...
  • Vote Up0Vote Down ianLianL
    tomas

    I would use it just as a general world atlas Country borders and major towns would be good For example a quick reference check on location of cities mentioned in TV news
    At this stage I cannot work out how to view this type of world map detail using Nav Free on my Galaxy S5 Mini
    Can you advise please?
    And as Oldie suggests perhaps you could also provide a brief comment on the main purpose for earth_osm.mca?
    Many thanks
  • Vote Up0Vote Down tomastomas
    that is not suitable, you cannot search for anything
    just show position on map (if you can call it map)
  • Vote Up0Vote Down IU0BMPIU0BMP
    Earth_osm.mca is required. I can't explain why, but if you delete it, you won't be able to use any map at all..
  • Vote Up0Vote Down ianLianL
    If Navigator cannot operate without the earth_osm file then the app is effectively 100+MB which is quite large
    I was hopeful there was some additional side benefit
    Some further insight on the need for this file would be helpful but thanks anyway
  • Vote Up0Vote Down hvdwolfhvdwolf
    Almost all nav_apps use some kind of world map to display country borders, coast lines and the like. Depending on the app that world map is 50 to 150 MB.
    As far as I know only Here Drive doesn't have a world map but those maps are much bigger then MNFs maps. So it wouldn't help you. 
    Besides: I really don understand why you complain about 70MB. Every phone nowadays comes with more internal memory and an SD-card costs absolutely nothing nowadays.

    Edit: And I was wrong: Here Drive also comes with a world map.
  • Vote Up0Vote Down OldieOldie
    I have some GB of maps on my phone (even some GB more OSM maps for Oruxmaps than for MFN maps), so I do not bother over 70 MB either.
  • Vote Up0Vote Down IU0BMPIU0BMP
    Just for your information: I also have another app: Maps.me. Not very good for driving, but its OSM based maps are very detailed (they even show small fountains for drinking water). File sizes are bigger though.
    Regarding Italy, they are:
    MFN: 329 Mb (plus 71 Mb for world map)
    Maps.me: 640 Mb (plus optional file for routing 221 Mb).
    Maps.me has very small files for "World map", but interestingly, you can view every country in the world (with some detail) just with these small files (without downloading the invidual country files). It just works differently. Maps.me might be good for pedestrian use, but for driving MFN wins hands down. Maps.me is poor regarding customization (no car profiles, no choice for fastest vs. shortest) and takes a long time to calculate routes. Its maps are nice to look but objects are too small if you look at the phone while driving. Once again, it's a good app for walking. Hopefully this was not too much off topic in this MFN forum :)
  • Vote Up0Vote Down OldieOldie
    We discussed different file sizes for maps here as well:

    http://forum.mapfactor.com/discussion/comment/10613#Comment_10613
  • Vote Up0Vote Down ianLianL
    All very interesting - thanks for this
    And I note Oruxmaps has a small world map too
    Oldie is right If the earth_osm file is not there then MFN does not work at all  Cannot detect any maps and asks if you want to download maps
    My comment about the effective app size is just an observation because I have a great admiration for "small and elegant" programmes  Yes storage is now cheap but too many apps just keep expanding without any real effort to make efficient use of RAM and/or storage  I cannot judge where MNF fits in here but it seems that earth_osm is actually a 70MB mission-critical add-on
    In the absence of any input from the MNF team then I guess we will just have to leave it at this point and wonder what earth_osm really does  Perhaps they might even now tell us a little?
    I still find the app is very good!
    Thanks all
  • Vote Up0Vote Down hvdwolfhvdwolf
    @ianL: I explained to you what the world map does: "to display country borders, coast lines and the like".
    And I forgot the big lakes.

    And with regard to the size itself: There is always a trade off in accuracy and simplication leading to smaller sizes.

    Take a Norwedish fjord outline for example: it might consist of 10.000 - 100.000 line segments with coordinates in real life. For a world map you want to reduce to the lowest level possible without loosing recignizable features at low zoom levels (zoomed out), so you might want to fit it into 100 or 1000 line segments. This is heavily done in digital map making, also for curvy roads, country/region borders and the like by every map maker.

    So how far will you go to provide "smooth, curved" lines at the smallest size.
  • Vote Up0Vote Down ianLianL
    @hvdwolf  Thanks for the additional comment
    As a relatively new starter in the world of mapping apps I am trying to understand how these things work  I have had trouble understanding why a world file (and not the specific country file) would be used to contain the detailed vector data needed to "display country borders, coast lines and the like" at all zoom levels
    Extrapolating in simple terms from your comments is the following roughly right?
    The earth_osm (world) file provides the skeleton geometric or basic outline data (eg coastline, borders) for all countries  For any specific country of interest the relevant outline data is extracted from the world file and then integrated with data from the specific country_osm file to give the maps and tools as displayed and used in MFN 
    Perhaps you would be good enough please to correct or extend this explanation if I've got it wrong  Does earth_osm have no other function than what you have described?
    I would still like to view the basic world map contained in earth_osm if that is possible  Do you know how I can do this?
    Thanks for your help
  • Vote Up0Vote Down luboslubos
    As a experiment you can download for example speed cameras then open navigator folder in some folder manager and delete data/earth_osm.mca and rename data/cameraspeed.mca to data/earth_osm.mca. If you run navigator after this you will see map without earth data.
  • Vote Up0Vote Down ianLianL
    @lubos  You're a genius   I have followed your general method
    and have also managed to display the world map  As you say just an experiment
    to see what information it provides and perhaps explain the need to have the
    world file

     

    What I did - suggest Exit from MNF before changing the files
    if you are interested

    Using an android file manager:

     

    1  World Map

    In folder Navigator/data

    Move country_osm.mca (in my case ) to another convenient
    folder T

    Copy sounds_en.mca to folder T and rename  Xsounds_en.mca

    Move Xsounds_en to Navigator/data folder and rename
    new_zealand_osm.mca

    Start MNF and you should have the world map  It shows white
    land mass against blue sea background borders and a few country names and
    cities  Essentially as @hvdwolf advised    Coastline defined only as colour
    transition white/blue  Image is clear for all zooms 

     

    2  Country Map without World map data

    Reinstate the original files to /data folder

    Use the same general method as 1 but move earth_osm to Folder
    T

    Move Xsounds_en back to /data and rename
    earth_osm

    Start MNF  This time the normal country display is provided
    except there is blue background over the land mass (like land is flooded) 
    Country data is hard to read  Coast line is defined by a purple line  I have
    confirmed this line is the OSM coast line  (Check in normal display - the white
    area does not "fill" the OSM coast line very accurately)   All normal MNF
    functions seem to work OK - limited check

     

    See screenshots if interested


     

    What does this tell us? From my observations it
    seems:

    a   the world map "coastline" is a rough approximation only 
    The country file contains the OSM coastline  Of course this does not matter at
    all for a land navigation app - use your eyes near the sea!


    b   earth_osm provides a white background for the land mass so
    the country_osm display/overlay can be seen easily  I cannot guess any other
    reason for this file  Importing 71MB for the purpose of providing a blank
    background to best render the country map seems a bit excessive when the
    appropriate region of the world map could be included in the country map file
    But perhaps someone can advise otherwise

     

    Thanks all for putting up with this lot
  • Vote Up0Vote Down luboslubos
    Earth mca contains borders of all countries... so you can see all borders without having all maps. Each country map contain border too(maybe more detailed-I am not sure about it). Important is that coastline is not border. Coastline is much more detailed, border is often quite far in ocean.

    Earth also contains information about capital cities(not sure if all of them are capital).

    I do not agree of using navigator without earth mca but if you really need it, you can go into navigator settings/map colors/edit color scheme/default/edit scheme/area/sky+ocean overall/background and there you can change background color to make map readable. Rivers will be visible, small lakes too, big lakes not.
  • Vote Up0Vote Down ianLianL
    lubos  Thanks for your help and suggestions
    I now have a confession to make  I asked from the beginning how I could view the world map and obviously no one thought I was such a total dumb-ass not to realise you can view the world by just zooming way out from the country map! I had always been working at the country level
    Still, the exercise has taught me a fair bit
    I agree it's certainly easier to just leave earth_osm in operation However, may be one day the MF team will consider decreasing the size of (or removing the need for) earth_osm by including the necessary earth background in the country maps  I assume this is what OpenAndroMaps must do  This would help to improve the initial download times for earth plus country map files Sometimes the download speed direct to device can be quite slow
    Again thanks for your assistance
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