Welcome to InspirePilots.com

Join the leading DJI Inspire community for free!

Cached Maps - How many square miles?

Discussion in 'Inspire 1 Discussion' started by FASTFJR, Dec 24, 2015.

  1. FASTFJR

    Joined:
    Nov 7, 2013
    Messages:
    717
    Likes Received:
    29
    Location:
    PA
    I posted this on the Phantom group but didn't get two far

    Trying to figure out how many square miles I can cached maps and at what level of detail. Is their some place that show you how much memory has been used? iPad mini 2 16gb
    Thanks
     
  2. Scotflieger

    Joined:
    Mar 29, 2015
    Messages:
    1,244
    Likes Received:
    576
    Location:
    Buckie, Scotland, UK
    I don't know the area covered but the memory taken up on a 16GB iPad is minimal. I normally cache the area I intend to fly at to a radius of 5NM (3 miles) and work over the area at 3 levels of zoom to ensure that all the tiles I need are fully download in detail. I have done this with up to 3 areas of operation without difficulty. However, there is a point where the 'older' maps will get overwritten but I can't tell after what time scale or after how many other loads this happens.
     
  3. RaptorMan

    Joined:
    Dec 18, 2015
    Messages:
    769
    Likes Received:
    213
    How do you force it to cache and how do you specify what to cache?


    Brian
     
  4. Kilrah

    Joined:
    Feb 3, 2015
    Messages:
    1,881
    Likes Received:
    728
    You just scroll manually over the affected areas at different zoom levels.
     
  5. RaptorMan

    Joined:
    Dec 18, 2015
    Messages:
    769
    Likes Received:
    213
    OK, then to cache all you need to do is scroll over the area at different zoom levels from within DJI Go -- how long is that data cached? I mean, do you at some point have to clean out the cache as it's gotten too big? If so, how is that done?


    Brian
     
  6. Waternut13134

    Joined:
    Nov 15, 2015
    Messages:
    67
    Likes Received:
    17
    It stays there until you close out the app I believe.
     
  7. RaptorMan

    Joined:
    Dec 18, 2015
    Messages:
    769
    Likes Received:
    213
    OK, that is good to know. This could be a problem when you want to fly in an area with no internet or cell service. If you could retain the cached data between operations of the Go app then you could pre-cache it at home or anywhere there internet service, but if that's not how it works then it won't do me much good in the Utah outback.

    If only there was a way to store the cached data on the tablet/phone for use at a latter time...


    Brian
     
  8. Kilrah

    Joined:
    Feb 3, 2015
    Messages:
    1,881
    Likes Received:
    728
    The cache is managed by the mobile device's operating system, not the app. It does whatever it wants and is not really predictable, but its purpose being to avoid redownloading frequently/recently accessed locations if you make sure to browse to the region of interest shortly before leaving there it will be in.

    Closing the app doesn't change anything.
     
  9. Scotflieger

    Joined:
    Mar 29, 2015
    Messages:
    1,244
    Likes Received:
    576
    Location:
    Buckie, Scotland, UK
    You will find that if you move over the area of operations at the 3 zoom levels (large scale, medium and close) and allow the map tiles to resolve fully (speed is dependent on your internet connection) the map is automatically cached and saved on your device. This should be checked before you go out to your planned site. I find that the map cache will clear after a period of time but I have not determined how long it lasts. There is also no way to determine what areas have been cached.
     
  10. FASTFJR

    Joined:
    Nov 7, 2013
    Messages:
    717
    Likes Received:
    29
    Location:
    PA

    Thats what I'm trying to figure out since they instructions from DJI are not there. Is their a memory / buffer built into the App? If so when does it get full (how can you tell) and when does it start to overwrite?
     
  11. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,716
    Likes Received:
    3,871
    As Scoftflieger's comments above, it is not clear exactly where the maps are cached or when it is overwritten.
    It would help if you explained specifically what you are trying to achieve.
     
  12. FASTFJR

    Joined:
    Nov 7, 2013
    Messages:
    717
    Likes Received:
    29
    Location:
    PA

    Its pretty simple, I just want to figure out how many square miles and what zoom level can be cached. I don't need to know, just curious. Since DJI has basically zero info about it, it makes me more curious
     
  13. RaptorMan

    Joined:
    Dec 18, 2015
    Messages:
    769
    Likes Received:
    213
    It's important to me as many of the places in Utah I want to fly are in the middle of nowhere and have no internet connection. Getting to the site only to discover the area that was cached is no longer there can be more than an irritant. This grey area between certainty and uncertainty is another irritant...


    Brian.
     
  14. Kilrah

    Joined:
    Feb 3, 2015
    Messages:
    1,881
    Likes Received:
    728
    Because as mentioned in my previous post even DJI have no control over it, it's managed by the mobile device's operating system, and given mobile device operating system vendors don't document the exact behavior of their location and mapping services (which likely changes from a device to another too depending on capabilities etc) there's nowhere to get the info from.
     
  15. FASTFJR

    Joined:
    Nov 7, 2013
    Messages:
    717
    Likes Received:
    29
    Location:
    PA

    Come on, of course they have control over it. I'm sure their is a buffer size.
     
  16. Kilrah

    Joined:
    Feb 3, 2015
    Messages:
    1,881
    Likes Received:
    728
    Yeah but it's set in the operating system, not in the DJI app.

    The way it typically works nowadays is that the operating system provides the mapping functionality, not the app. The app just tells the system "draw me a map of location X at zoom level Y", and the system does the actual job of fetching and managing map tiles.
    The whole purpose of that is precisely so that any map loading and caching is done only once by the system globally for all apps installed on the device, instead of each app loading its own data like in the past (saving on the related network usage, storage requirements and battery drainage involved).

    The OS will use many things like where you live, where you work, which areas are more frequently visited or loaded (by any app) etc to determine what to keep in cache, for how long etc and is thus in essence unpredictable.

    Apps may or may not still have the possibility to manage things on their own, I'm not up to speed with the latest developments on all platforms anymore, but I remember a year or 2 ago when some services were switched to not being accessible outside of the OS handling anymore to encourage/force app developers to go through the system.
     
    The Editor likes this.
  17. IrishSights

    Joined:
    Jan 14, 2014
    Messages:
    1,954
    Likes Received:
    453
    Location:
    Bangor, Northern Ireland, UK
    As you are so sure it would be really helpful to the OPer if you could share your gleaned surity. Most buffers have a max size but are nevertheless dynamic in use depending on other demands of the OS.