Welcome to PhantomPilots.com

Sign up for a weekly email of the latest drone news & information

Would Mavic be suitable for photogrammetric purposes?

Discussion in 'Mavic Discussion' started by PeteM, Oct 2, 2016.

  1. PeteM

    Joined:
    Sep 28, 2016
    Messages:
    44
    Likes Received:
    10
    I simulated (through a professional software) various photogrammetric flights with Mavic.

    I feel I can say that this drone is ABSOLUTELY not suitable for this type of application.

    Setting a flying height compatible with the accuracy required to the ground, setting just a discrete overlapping and speed parameters, due to the reduced FOV, the complexity of the flights (number of strips and photos) increases in an unacceptable way.

    The issue ends here for me... the optics of this drone is not suitable for making topography...

    I hope that many will throw away their P4 for Mavic so I'll be able to buy my first Phantom at a low price...
     
    skiptv, Jody Pitts, MrTommy and 2 others like this.
  2. petaqui

    Joined:
    Aug 29, 2016
    Messages:
    9
    Likes Received:
    0
    Location:
    Jaca, Spain
    Can you develop further? Can't see your point at all...
     
  3. With The Birds

    Joined:
    Jan 4, 2016
    Messages:
    2,572
    Likes Received:
    728
    Location:
    Australia
    And you didn't consider flying higher?
     
    Bigdz and djsergeatl like this.
  4. Meta4

    Meta4 Moderator
    Staff Member

    Joined:
    Jan 8, 2014
    Messages:
    7,692
    Likes Received:
    3,424
    The P3/4 have a lens equivalent to a 20 mm lens on a full frame 35mm camera and the Mavic has the equivalent of a 28mm lens.
    How is it that this small change in the field of view makes photogrammetry impossible?
    Surely it's a just a small matter of flying a little higher to capture the same area.
    Or capture it in better detail at the same altitude.
     
  5. PeteM

    Joined:
    Sep 28, 2016
    Messages:
    44
    Likes Received:
    10
    Sure. Here's a real example with real numbers.

    Area to be mapped: 275.535 m2

    Flight altitude: 40 meters
    Overload factor: 25%
    Overlap factor: 69%
    (these parameters are the minimum acceptable for me)

    With Phantom 4 you can fly at 4 m/s, taking a picture every 4 s, for a total of 406 photos.
    With Mavic you can fly at 4 m/s, taking a picture every 3.5 s, for a total of 691 photos.

    285 more photos mean an exponentially more complex post-elaboration...
     
  6. Meta4

    Meta4 Moderator
    Staff Member

    Joined:
    Jan 8, 2014
    Messages:
    7,692
    Likes Received:
    3,424
    So what's to stop you flying a little higher and having less photos?
     
  7. With The Birds

    Joined:
    Jan 4, 2016
    Messages:
    2,572
    Likes Received:
    728
    Location:
    Australia
    Simply fly at 53m alt instead of 40 and you will have the same number of images. I am having difficulty understanding what the issue is. Even if you wher to fly at 40m with extra images required the final result would have increased resolution.
     
  8. PeteM

    Joined:
    Sep 28, 2016
    Messages:
    44
    Likes Received:
    10
    The higher the flight, the less the precision on the ground...

    Rising the altitude also means having less visual contact... increasing the distance between the drone and the commands in your hand (losing the drone)... in general, flying at a low altitude is safer...

    All the similar surveys I've worked up with (flights not made by me) were performed at an height of between 35 m and 40 m... in all the tutorial (with phantoms) I've seen on youtube the height is the same... so I think its the right choice...
     
  9. 4wd

    4wd

    Joined:
    Mar 31, 2014
    Messages:
    2,532
    Likes Received:
    421
    Location:
    North York Moors
    Why would the height required to use a phantom be the only suitable option.
    You only need go a few metres higher.
    If the argument is it's then harder to see well you might have that anyway since it's smaller.
    So buy up ten years worth of ebay P4s, problem solved.
     
  10. With The Birds

    Joined:
    Jan 4, 2016
    Messages:
    2,572
    Likes Received:
    728
    Location:
    Australia
    You won't loose any precision and stick movements will be of less consequence as distance increases for a given focal length. In this instance flying at increased height to maintain FOV the effect of any lack of precision in flight will be of identical effect.

    In general flying at higher altitude is safer (within sensible limits). Your mavic will be in a similar condition if it drops form 53m as it might be from 40.
     
  11. DarkEnergy

    Joined:
    Sep 24, 2016
    Messages:
    23
    Likes Received:
    6
    Location:
    Cambridge, UK
    I suggest you continue to do simulations
     
  12. m0j0

    Joined:
    Dec 26, 2015
    Messages:
    1,532
    Likes Received:
    529
    So you don't have either and haven't purchased either? Nice.


    Sent from my iPad using PhantomPilots
     
    phantom13flyer likes this.
  13. Merko

    Joined:
    Mar 31, 2016
    Messages:
    25
    Likes Received:
    13
    Must be a troll post :p
     
  14. PeteM

    Joined:
    Sep 28, 2016
    Messages:
    44
    Likes Received:
    10
    Still don't understanding why I should fly 20 meters higher just to compensate a "castrated optics"... if ALL professional, non consumer, expensive drones for land surveying mount "wide" lens there will be a reason...
     
  15. With The Birds

    Joined:
    Jan 4, 2016
    Messages:
    2,572
    Likes Received:
    728
    Location:
    Australia
    The Mavic lens is considered wide. What non consumer professional expensive systems are you referring to?
     
  16. BruteForce

    Joined:
    Sep 23, 2016
    Messages:
    29
    Likes Received:
    9
    Right off of DJI FAQ's:

    What’s difference of camera between Mavic and Phantom 4?

    "The two cameras have the same features, but the Mavic’s camera has a smaller FOV, is able to focus as closely as 0.5m and can be rotated 90° for portrait shots and selfies. The Phantom 4’s larger FOV makes it better suited for landscape imaging."

    Portability and all the great features of the Mavic make it my choice, but it may not be for everyone.




    Sent from my iPad using Tapatalk Pro
     
    Christopher D Odom and WetDog like this.
  17. petaqui

    Joined:
    Aug 29, 2016
    Messages:
    9
    Likes Received:
    0
    Location:
    Jaca, Spain
    Thats the point then, if you want a drone for surveying maybe then you should go for a bigger-more expensive-more "pro" drone, not this kind of drone for photography/videography and not surveyance
     
  18. Meta4

    Meta4 Moderator
    Staff Member

    Joined:
    Jan 8, 2014
    Messages:
    7,692
    Likes Received:
    3,424
    There's nothing magical about 40 metres altitude or about the FoV of the Phantom lens.
    The default height used by DroneDeploy is 243 feet = 74 metres but you are free to raise or lower your height to whatever you like.
    It's obvious that you haven't flown a Phantom from your comments about losing it because you go a little higher.
    And the Phantom is just as safe at any altitude.
    Go out and look at DroneDeploy or MapsMadeEasy to see how to do a photogrammetric survey with a drone because the assumptions you are working don't make any sense.
     
    FT in Japan and phantom13flyer like this.
  19. DarkEnergy

    Joined:
    Sep 24, 2016
    Messages:
    23
    Likes Received:
    6
    Location:
    Cambridge, UK
    If you don't understand such a simple point, I strongly suggest to dedicate yourself to something simpler than photogrammetry!!
     
  20. MacCool

    Joined:
    Nov 23, 2014
    Messages:
    756
    Likes Received:
    167
    Location:
    midwest USA
    1. You say "TESTED", but what you actually mean is "SIMULATED". You don't really know how the Mavic will perform, you only know how your simulation performs.
    2. It's no surprise that some drones wouldn't be optimally suitable for some applications
    3. This is a pretty narrow and specialized application. Certainly won't represent a dent in DJIs sales.
    4. If you need a drone for professional application, you should get a professional-grade drone, not a consumer drone that's marketed toward convenience and backpackabiity. It sounds like your best compromise would be a Phantom 4 consumer-grade drone.
    5. Sounds like the Mavic won't work for your needs
    It's a simple problem...Mavic won't work for you. Drive on.