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evan.roy

Suveying 400 Sq Km. Area

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Helllo everybody I'm Evan from India. I have been working as a GIS Professional for the past 7 years. Now in near future we might have to acquire aerial photographs of 400 Sq Km and prepare orthophotos. The study area has some significant undulations and forest cover as well. What I would like to know Can I propose a UAV survey method for this kind of project? If yes then roughly how long will it take to complete the flying (considering 10 cm. GSD)? What kind of UAV & software combination (e.g. DJI Phantom 4 with Pix4D Mapper) should I think about?

Any help is much appreciated!

 

-Regards,

Evan Roy

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Hi Evan,

I am not an expert but based on my limited geomapping experience, a consumer level quadcopter (Phantom) is not the tool for such a large area (400 sq.km?). I did a 200 acre college campus once (don't want to ever do it again) with a DJI Phantom 3 Pro, took me a month. The limited flight time per battery is not practical for large areas . 400 square km is 9,900 acres! I'm no math wizard but I get about 7 acres per Phantom battery so 9,900=1,400 flights???

An area that large requires a fixed wing with longer battery life or a manned aircraft. Of course there are many requirement-limiting choices, such as cost.

http://www.uavfactory.com/

http://uav-solutions.com/

http://www.unmannedsystemstechnology.com/company/arcturus-uav/

https://www.sensefly.com/home.html

Lots of research ahead, Evan. :D Hope this helps.

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1 hour ago, Uaviator53 said:

Hi Evan,

I am not an expert but based on my limited geomapping experience, a consumer level quadcopter (Phantom) is not the tool for such a large area (400 sq.km?). I did a 200 acre college campus once (don't want to ever do it again) with a DJI Phantom 3 Pro, took me a month. The limited flight time per battery is not practical for large areas . 400 square km is 9,900 acres! I'm no math wizard but I get about 7 acres per Phantom battery so 9,900=1,400 flights???

An area that large requires a fixed wing with longer battery life or a manned aircraft. Of course there are many requirement-limiting choices, such as cost.

http://www.uavfactory.com/

http://uav-solutions.com/

http://www.unmannedsystemstechnology.com/company/arcturus-uav/

https://www.sensefly.com/home.html

Lots of research ahead, Evan. :D Hope this helps.

Thanks for your reply! Will check the links and let you know :)  thank you again..this was helpful

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@evan.roy You can get more than 7 acres per battery! I'd think you'd be able to get something more along the lines of 30-100 per battery depending on a few variables. In this circumstance, the Phantom still isn't very practical.

One option would be to go with a DJI Matrice, double up on batteries, and see how that goes.

The most likely option is to do some sort of plane and use a modified Canon camera with 3DR Pixhawk to run the plane. 

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@Lewis@IcarusAerials Doubling up batteries a great idea! I had no idea that this could be done! I was looking up different 3DR products and found them really amazing. Being a novice I still gotta do a lot more research :) but really thank you for your tip!

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@evan.roy I was just rereading your post. If you are looking for 10inches/pixel, you could fly much higher and cover more ground than I'm used to. I don't know what (if any) height restrictions you have. If you are a novice, and can gain decent access to the area to take off from, I think doing a UAV is the better approach.

If you are comfortable flying a fixed wing / learning that, then for a project of this size, I think it is the most efficient route. 

A good question would be, do you see yourself doing this again in the future? If so, I'd go with the fixed wing and get going with that.  

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4 hours ago, Lewis@IcarusAerials said:

@evan.roy You can get more than 7 acres per battery! I'd think you'd be able to get something more along the lines of 30-100 per battery depending on a few variables. In this circumstance, the Phantom still isn't very practical.

One option would be to go with a DJI Matrice, double up on batteries, and see how that goes.

The most likely option is to do some sort of plane and use a modified Canon camera with 3DR Pixhawk to run the plane. 

Yes, If I push it I can get 10-12 acres per battery but I like to land with at least a 20% reserve. I also never do less than 80% overlap, anything less seems to be a waste of time, find myself having to go back out and repeating the job. Consumer level quads simply are not ready yet for large mapping jobs (one can certainly build a homemade job with longer battery life) surely not 9K acres. A manned aircraft would be simpler but not cheaper...

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@Uaviator53 We like to land with 30%, and for the resolution he is looking for, he should be able to do more than 10-12 per battery. 

I personally think 80% overlap is overkill. What information is missing when you do less?

I'm not saying it would be a cake walk to do 9k, you'd need some processing power, do it in chunks, etc, but for someone who is new, doing this once, with the right budget, you could make it happen. 

With enough flight time on a fixed wing, that is probably the best bet. Going to be way cheaper than a manned flight!

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80% IS overkill, Lewis, me likes overkill. The quality of the final geomap is much better. I also like to do a second pass at 90 degrees offset. Makes for buffo images, specially 3D. If I was just mapping an empty dirt field with few features, then yes, I 'd do it at maybe 60% overlap. Most of the geomap jobs coming at me so far involve structures.

We both agree a consumer level quad (like the DJI P4 Evans was asking about) is not optimum for a 9,000 acre job. FIxed wing UAV or manned airplane is best.

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Manned airplane is absolute out of question. The only reason I think (do correct me if I'm wrong) UAV survey could be a game changer in India for it's ability of capturing stereo images with great accuracy. This way it can save money & time for ground survey (like total station) and it works great as most recent base map for a GIS user. Both satellite images and aerial photos (manned aircraft) are way too expensive. But as you both said a fixed wing UAV should do the job just fine. I'm still looking at different options but I think one UAV (having longer fly time like 50 mins to 1 hr.) with 2 extra batteries would be sensible idea. With these I think it might take upto 15 to 20 days to cover the area.

@Lewis@IcarusAerials@Uaviator53 thanks both of you and I'm all ears for your suggestions :)

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On 7/12/2016 at 7:20 AM, evan.roy said:

Manned airplane is absolute out of question. The only reason I think (do correct me if I'm wrong) UAV survey could be a game changer in India for it's ability of capturing stereo images with great accuracy. This way it can save money & time for ground survey (like total station) and it works great as most recent base map for a GIS user. Both satellite images and aerial photos (manned aircraft) are way too expensive. But as you both said a fixed wing UAV should do the job just fine. I'm still looking at different options but I think one UAV (having longer fly time like 50 mins to 1 hr.) with 2 extra batteries would be sensible idea. With these I think it might take upto 15 to 20 days to cover the area.

@Lewis@IcarusAerials@Uaviator53 thanks both of you and I'm all ears for your suggestions :)

Evan, I am seriously considering my next UAV purchase; the Firefly6, VTOL, $6,000 USD for the mapping version, ready to fly. they tell me it can  map 200 acres in one flight (app. 50 flights for your task) .  Tell Derek I sent you. :D

Derek A. Lyons

Sales Consultant

 BirdsEyeView Aerobotics

m: (352) 283-3402

e: derek@birdseyeview.aero

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@Uaviator53Google says 200acres is .80 sq. km.! which means near about 500 flights needed to cover that much area. I really need something with which I can cover at least 10 sq. km.(2471.05 acres) in a single flight :( you can take a look at the .kml I have attached. But we will buy a smaller version also. So if your experience with firefly6 goes well I will surely buy one :)

Area.kmz

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Evan,

My apologies. Looks like my initial math was way off. 400 sq. km. is not 9,000 acres but more like 98,000 acres. That's a 3-4 month job. I mean, I suppose you could make it a career 9_9.

Lets say you have enough batteries for the Firefly6 (I have no idea how many needed) to fly 5 flights per day x 200 acres per flight and recharge overnight. (daylight only and avoiding twilight=long shadows)100 days=3 months...

Thanks for the KMZ file!, looks like quite a challenge, with a difference in terrain elevations of almost 900 feet. Since none of the "affordable" UAVS have terrain avoidance(yet), the most cautious approach would be to break the area down in small chunks with similar elevations to avoid "controlled flight into terrain" as the pilots call it. Of course flight height is dependent on desired GSD..

Lewis, jump in here...

PS- I am not purchasing the FireFly6 any time soon, perhaps another 4 months and only if business continues to grow.

      Evan, with respect...I'm glad is you and not me.....:S

 

Maybe I'm wrong, but using your KMZ file in Google Earth, GE tools compute 10 sq km.=2,500 acres=3.9 sq. miles for the square you marked???

Edited by Uaviator53

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"Significant undulations and forest cover" was mentioned so I figured a multi rotor. If a road goes through the mapping area than fixed wing is the answer. Sounds a tad remote so a road might work well. Depending on cover.

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13 hours ago, Mantis2 said:

It's a one year job...............with a Uas.

Not with a fixed wing UAS.

Either way, 98,000 acres is a job for a manned aircraft.

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8 hours ago, Uaviator53 said:

Either way, 98,000 acres is a job for a manned aircraft.

One question no one has asked is HOW MUCH MONEY DO YOU HAVE for the project. How much time? Regardless unless you are talking a military grade drone I don't think you are doing this with a commercial UAV quickly. Manned Aircraft seems to be the way to go. 400sq KM is, as you know, a huge amount of area to cover with a UAV.  Even If you don't have the VLS rules we have in the USA in India you are still talking safely about  .5 mile to 1 mile ONLY IF THERE IS NO OBSTRUCTIONS as most UAVs are VLS with the transmitter. Buildings, trees, ETC... will get in the way. Plus, with a Phantom 4 you are only talking 18 or 19 minutes before the Low Batt alarm starts going off. 

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