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Netbooks, PDA and Phones Thread, Google Maps KMZ file limitations, need advice in Technical; I have spent a few weeks making up some Google Maps and have saved these in .KMZ format with the ...
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    Dos_Box's Avatar
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    Google Maps KMZ file limitations, need advice

    I have spent a few weeks making up some Google Maps and have saved these in .KMZ format with the intention of looking at them on Google Maps Mobile. I've uploaded them to a location and can connect to them fine on my Android phone, however, all of the locations in each file are not shown. In fact, only about 100 are (with a total of about 400+ in each KMZ file) visable in each file. I can find several posts online with people asking about the 100 places limit, but none of these have had any replies, and I'm struggling to find out any information on limitations on KMZ files being viewed on mobile devices.
    I can't unfortunately give you a link to these files as it's a project I have running and still want to keep under wraps for the time being, however if anyone has any information about imposed limitations or workarounds please let me know as it's a bit frustrating.

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    Dos_Box's Avatar
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    Typical. Still looking for a solution, and now my post comes up number 2 in Google when seaching for it!!

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    Dos_Box's Avatar
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    Well, I've found out a little more information on their KMZ/KML documentation site here: KML Support - KML - Google Code

    In particular this section on caveats on using KMZ/KML files on mobile devices:

    There are a number of ways to access KML in Google Maps for mobile:

    • KML is mixed in with search results for many queries. Try searching for "wedding tahiti".
    • Enter a KML URL into the search box, like "http://bbs.keyhole.com/ubb/download.php?Number=438084"
    • On a Blackberry with Google Maps for mobile installed, go to the web browser and find a page with a link to a KML document (.kml/.kmz). Clicking the link should invoke Google Maps for mobile and automatically bring up the KML file on top of the map.

    A couple of caveats:

    • There are a number of aspects of KML that don't work well (or at all) on a small 2D screen, such as altitude and camera angle.
    • In some cases, the KML document is trimmed so that it fits on a phone. For example, images are scaled, and very large KML files are truncated.
    The thing is my file (KMZ) is only about 24KB in size which is about 124KB as a KML (the 'Z' in KMZ stands for zipped BTW), which is still quite small compared to the maximum allowable size of 3MB listed on the site. I shall dig further to see if there is any concrete information on these restrictions.

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    Dos_Box's Avatar
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    Well it seems it does truncate the file to display KMZ/KML locations shown only in/around the current map view. For instance, if I zoom into my hometown of Preston and open up a KMZ of locations for Lancashire it will only show those in and around Preston. However, if I close the layer, zoom in on a location say in East Lancashire and reopen the map it will then show locations centred around the current view, but close the orginal ones. It will not show locations contained in the KMZ file outside of that area unless you zoom in and reopen the map. This may have something to do with the fact that they truncate the files for display on a smaller screen. I am now going to try a different technique and add them to my Google Maps via the web based Google Maps and see if they open fully in Google Maps Mobile.

    Edited to add: It does exactly the same thing when you connect to My Google Maps via Google Maps Mobile, so I assume that this behavior is limited by the device/screen size. I'm going to try this on a larger screen Android tablet with GPS fitted once I get home later to see if the device screen size is a deciding factor or whether it is the device OS/type itself forcing the truncating of the data shown.
    Last edited by Dos_Box; 22nd August 2011 at 04:36 PM.

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    bossman's Avatar
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    @Dos_Box:

    Found this online conversion tool for all types of maps wondered if was of any use

    GPS Visualizer

  6. Thanks to bossman from:

    Dos_Box (22nd August 2011)

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    Dos_Box's Avatar
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    Cheers, that looks very handy. I'll take a look later and let you know how it works out.

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    Dos_Box's Avatar
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    I had a deeper look at GPS visualizer, but it's not what I need. It is essentially an application for taking raw GPS data and converting it to other formats and, in the case of KMZ files being able to bulk edit features. It's a very handy site which I've bookmarked as it will allow me to do bulk modifications at a later date.

    As regard to the limitations of KMZ files being used on mobile devices I made some headway in finding out what the possible reasons are and why they have been implemented. I tested loading the remote KMZ file on an Android tablet and an old first generation iPod touch last night. The Android tablet (a WitsTech A81E) has a GPS module buit in but still only downloaded 100 places using both Google Maps Mobile and the browser based Google Maps. However the iPod Touch downloaded all 400+ places via the Google Maps plugin, which then promptly killed it almost stone dead performance wise. What I am currently surmising is that Google Maps Mobile prevents the devices grinding to a halt after acertaining exactly which device it is being displayed on. If it thinks the device will not be able to cope effectively with more than 100 placemarks in the KMZ file it will only download the locations nearest to where the user is currently located or where the user currently has their Google Map focussed on. I'm not sure of the deciding factor (or combination thereof) but I assume it will include whatever platform, screen size and processor/device capability the user has.

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    SYNACK's Avatar
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    Can you not split out the KML files into batches of say 50 and then load them programaticlly based on the initial or current map loation. That may get around the problem.

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    Dos_Box's Avatar
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    Not really alas. The files are created with the locations added in an ad-hoc fashion, so you'd have to spend an age working out which location went where, also the way in which Google Maps loads the truncated file already does this i.e. it loads up the locations nearest your location or where ever you have the map focussed on. The problem is there is so little information about how this actually works and so many people now wanting this functionality that I'm sure someone will be working on it, and perhaps it is something Google themselves may be trying to resolve.
    Last edited by Dos_Box; 23rd August 2011 at 03:18 PM.

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    SYNACK's Avatar
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    Ok, how about forcing an unload and reload after moving outside a certain radious of the initial load point. This would make the device reallocate the correct ones close to the current location. A bit of a hack but thats web based stuff for you.

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    Dos_Box's Avatar
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    You can do that manually quite easily, but I suspect what I am after is an overall effect. Where a map can be loaded covering a large area (60+ miles square) and all points are shown, otherwise it's like looking in a shop window and seeing only a quarter of the shelves have anything on them. It's hardly enticing.



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