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Usable object distance for search and rescue?
330 12 8-21 13:00
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SeaRangers
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Hi All,
I've been asked to determine if a Mavic 2 Pro would be useful for tasks, such as locating a small boat on the ocean's surface.  I've done some back-of-napkin calculations, and would appreciate any advice.  Here's what I have so far:
- Let's say the camera resolution is around 5000 pixels on the long side of the image.
- Let's say we're looking for a boat that's 4 meters (12 feet) long.
- I think I can recognize a boat shape in a photograph, if it's at least 20 pixels long, and at least 5 pixels wide.
- That means that I should raise the drone high enough so that, in a single photo image, I get an outer edge that's 5000 pixels of light data and about 1 kilometer of ocean surface (5000 * 4 / 20).

But I can take more than one image.  And perhaps my calculations are off-base.  Intuitively, it feels that I should be able to "see" a wide area, one kilometer diameter seems too small.  

Has anyone tried this in real life?  What were your limitations?

8-21 13:00
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DAFlys
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I've photographed big ships at 12km and they were easily recognisable.  I think a lot will depend on the sky quality,  haze could easily reduce your distance.
8-22 00:42
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droneflyer101
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Would defo do the trick, I have worked with many police forces, rescue teams that use them. I would personally recommend the Mavic Enterprise Series. I have one for my company off Heliguy, great support and even better after-sales than anywhere else
8-22 00:58
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Cetacean
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Aloha SR,

     What you need to be looking at is the Mavic 2 Enterprise series;

https://www.dji.com/mavic-2-ente ... ndsite&from=nav

These are the ones designed for Search and Rescue and have already been used very successfully.  One was even used in the Notre-Dame fire (the reason will intrigue you).  They are not cheap but they are well equipped.

     Hope this helps!

Aloha and Drone On!
8-22 01:39
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SeaRangers
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DAFlys Posted at 8-22 00:42
I've photographed big ships at 12km and they were easily recognisable.  I think a lot will depend on the sky quality,  haze could easily reduce your distance.

DAFlys, how big were the ships?  I can probably extrapolate my small boat use by dividing your ship size by my 9 feet.
8-22 08:06
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SeaRangers
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Cetacean Posted at 8-22 01:39
Aloha SR,

     What you need to be looking at is the Mavic 2 Enterprise series;

droneflyer101 and Cetacean, thanks for the advice.   I will definitely look into purchasing an Enterprise one, if I get the grant money to get more drones.  But for now, I'm limited to a Mavic 2 Pro -- that's the drone they got donated.  At the celebratory event for the donation, a woman asked if the drone would have been useful for finding her young son, who went on a boat joyride the month before (the kid is fine).  I promised to research.  I'd figure this out experiementally by lifting up the drone and seeing how far I can detect a fishing boat, but I'm no longer in the area.  Hence the attempt at a rough calculation.
8-22 08:10
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SeaRangers
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SeaRangers Posted at 8-22 08:06
DAFlys, how big were the ships?  I can probably extrapolate my small boat use by dividing your ship size by my 9 feet.

And were you at the limit of how far away you could be to still see them on a photo?
8-22 08:14
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Cetacean
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SeaRangers Posted at 8-22 08:10
droneflyer101 and Cetacean, thanks for the advice.   I will definitely look into purchasing an Enterprise one, if I get the grant money to get more drones.  But for now, I'm limited to a Mavic 2 Pro -- that's the drone they got donated.  At the celebratory event for the donation, a woman asked if the drone would have been useful for finding her young son, who went on a boat joyride the month before (the kid is fine).  I promised to research.  I'd figure this out experiementally by lifting up the drone and seeing how far I can detect a fishing boat, but I'm no longer in the area.  Hence the attempt at a rough calculation.

Aloha SR,

     That makes your questions a little clearer.  Do be aware that the M2P does not have the attaching points that the M2 Enterprise series does.  But the M2P can carry two "headlamps" by LumeCube that are designed for the M2P and an accompanying M2E can carry the speaker system available for the M2E series (and many other attachments).

     The M2E Dual also has a visible light camera and InfraRed (FLIR) camera in the single camera housing that is mounted.  That makes the heat of living victims easier to find in Search and Rescue (S&R) operations.  Body heat stands out vividly in the cold ocean or lake when using a FLIR system.  This also works on glaciers, in snow and other dark (and cold) environments.

     May I suggest that you look over the M2 Enterprise DJI web pages enthusiastically to see how much it will assist your S&R efforts.  Then realize that you have the M2P that can carry the LumeCube headlamps (or other brands).  That will save a lot of money.

     How often do S&R operations have to halt at night.  The M2E Dual system works better at night so you can fly at any time as long as you have batteries.  DJI also sells charging systems for the intense charging that is required in an S&R operation.

     As an example, with two of you, one flying the M2P with headlamps and the other flying the M2E Dual with speakers at night, you can perform a S&R, find the victim because the body heat shows up so well with FLIR, hover over the victim and take photos and then fly back.  The GPS coordinates show up in the photos properties and in the flight records.  They can even be available in flight (or hover).

     Provide the coordinates to the rescue party and they can be on the way before you can change batteries.  Then with the fresh batteries, you can fly both birds over the rescue party and on to the victim.  Then you can loiter over the victim with a pep-talk or questioning until you have to return for new batteries.  Any new information can be relayed to the rescue party before they even reach the victim.  Repeat as needed.  The lights and voice communication are very reassuring for the victim.

     Although the victim cannot talk back, they can nod or wave in response to questions.  They can indicate numbers.  There is a lot of information they can provide without speaking that you can see in the Live View and respond with the speakers for confirmation.  That information can be useful for the rescue party or for a second team getting ready.

     Hope this helps!

Aloha and Drone On!
8-22 17:16
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DAFlys
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SeaRangers Posted at 8-22 08:06
DAFlys, how big were the ships?  I can probably extrapolate my small boat use by dividing your ship size by my 9 feet.

Heres an example, this boat is about 70ft.
8-22 22:13
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SeaRangers
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DAFlys Posted at 8-22 22:13
Heres an example, this boat is about 70ft. [view_image]

How far away were you?

8-23 12:47
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SeaRangers
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Cetacean Posted at 8-22 17:16
Aloha SR,

     That makes your questions a little clearer.  Do be aware that the M2P does not have the attaching points that the M2 Enterprise series does.  But the M2P can carry two "headlamps" by LumeCube that are designed for the M2P and an accompanying M2E can carry the speaker system available for the M2E series (and many other attachments).

Thanks Cetacean.  This is a lot of great info that I will be copying and referencing in the future.  Right now, there is zero money to be put into the project.  I'm just looking to find numbers on the current setup -- a Mavic with a 4K camera, flying X meters high, photographing a circle of Y kilometer diameter.  I can assume clear air and smooth ocean, and that's about it.  Just looking to see how many kilometers away I can have enough photographic resolution on.  My back-of-napkin calculations say 1 kilometer is my max diameter, and I'm hoping I'm wrong and other people have seen further.
8-23 12:52
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Cetacean
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SeaRangers Posted at 8-23 12:52
Thanks Cetacean.  This is a lot of great info that I will be copying and referencing in the future.  Right now, there is zero money to be put into the project.  I'm just looking to find numbers on the current setup -- a Mavic with a 4K camera, flying X meters high, photographing a circle of Y kilometer diameter.  I can assume clear air and smooth ocean, and that's about it.  Just looking to see how many kilometers away I can have enough photographic resolution on.  My back-of-napkin calculations say 1 kilometer is my max diameter, and I'm hoping I'm wrong and other people have seen further.

Aloha SR,

     What you are doing is looking into the realm of spy cameras and spy satellite technology.  Those are the algorithms and other formulas you will need, but why?   The only competitor you have to worry about is a helicopter with camera on a gimbal that rents for the cost of a new M2E Dual Plus system per hour - and that is cheap.  Those are the only real numbers you need.

     You need to learn how to fly your M2 Pro and calibrate your photos and video as you need to show any benefactor or funding agency.  The responses you get here on the Forum will only give you ball park figures (as you have seen courtesy of DAFlys, etc.) and you can get those on your own by flying your M2P and getting your own video and photos.  But to get the most out of your M2P, you will have to read the manual and digest and understand the SPECs.

https://dl.djicdn.com/downloads/ ... _Manual_V2.0_en.pdf

     When you are ready to get funding for a real (as in dedicated) S&R system like the M2E Dual, post it and I will post one of the proposals (updated) I have recommended for others depending on your specific needs.  But remember, the only thing that compares to what you are proposing with your M2P is a helicopter with gimballed camera that costs per hour what you can get an entire M2E Dual system for.

Aloha and Drone On!
8-23 16:42
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SeaRangers
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Er, I feel we're talking about different thigs.  I'm not looking for a dedicated S&R solution.  I'm just looking for a back-of-napkin calculation for "how far can the Mavic see".  I made my own calculation -- I think the photo resolution will allow for about 1km distance.  I was just looking for verification.  I'm not near the Mavic right now -- it's on the other side of the world, so I can't experiment.  

Thanks anyway for the help.

8-26 08:18
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