Large area planning and processing - 53000 acres


#1

Hi, I have read a number of posts on large area projects and have a good idea of how to tackle it… slowly it would seem. I have a small catchment to fly with a P4P and 6 batteries. 53 000 acres (21 500 ha) with a the site varying in height for 65 Feet (20 m) to 2444 feet (745 m) above sea level. I have read Gary’s post from April 19 and he seems to have the most logical approach so far. My set up would be as follows:

Flight Height 300m - 9 cm pixels
Sidelap 65%
Frontlap 75%
Speed 15 m/s

I realize that I am going to probably have to increase both overlaps to 75 or even 80% to be sure that I can stitch the images successfully. The main issue I face is planning such a large area in terms of the height difference. I can isolate the higher altitudes and fly them as separate missions.
My concerns are being able to process these images later with different heights and very different light conditions as this will take more than a week to fly. Anybody have experience or tips using a P4P over an area this size?


#2

Rent a fixed wing.

Your altitude at 300ft right? Not meters.


#3

G’day Drone_Pilot1,

I must say that based on a recent job I did (ref. Renting Equipment) covering some 2000ha (4800acres) with around 300m of relief changes in 4 days (using a 2016 Mavic Pro), that your plan of covering this amount of terrain with even greater relief sounds like its going to be a lot of fun and hard work.

I used GoogleEarth to help plan all of the 40 individual flights and had the minimum overlap — in our case this was about 67m at the flight altitude of 120m/400’ (at the minimum 60% sidelap). At 300m and 60% that would be around 173m.

As a starting point I applied a topographic contour layer to the entire project area. This enabled me to check the relief changes. The ‘Show Elevation Profile’ tool is very handy to use in this instance, as one can ‘segment’ an area to consider the other challenges of flying large areas: A. battery maintenance and B. ensuring that the line of sight between operator and UAV is maintained (a legal requirement here in Australia) — and to help the UAV stay in contact with the RC.

We use a simple map key convention for all of our flights so that file management of individual missions is easily dealt with when processing.

Going west to east its like this for individual flight plans — changing the first number as you go south with each set of missions e.g.

1-1 1-2 1-3 1-4
2-1 2-2 2-3 2-4 2-5
and so on

I’d strongly recommend that following each mission that you download the data for that mission before you take off for the next cataloguing this mission according to the map key you develop when planning the all of the flights. Otherwise you will find that its very difficult and time consuming to locate the start and finish of each mission when scrolling through 1000’s of images (I learnt that the hard way at the end of day 1!!).

The only other concern I have (apart from the light conditions) will be viewing all of these flights — especially if you want to view them all at once. We’ve found that to be a major concern especially when a lot of our farm planning clients don’t have great computers and so we’re still working on the best solution there.

GoogleEarth, for example, will only display overlays of a max 10,000 pixels wide before it cracks the sads. Otherwise if you’re viewing in QGIS or other GIS/CAD/Graphics apps then you need to go and make a cup of tea every time you scroll across the page — and that’s with our computers which are pretty high spec.

I wish you every success with this project, and like Michael would suggest looking a renting a fixed wing but understand too that with time and planning you could also do this with a P4P - just a LOT of time and a LOT of planning (and processing).

All the best,

Darren J. Doherty
Regrarians.org
Drone Deploy Flylanthropy Partner


#4

Hi Michael, I agree, a fixed wing would make sense for an area this size but I don’t get to make that call. I was told it would have to be 300m or 984 ft. We initially looked at flying lower but over that size area it would simply take too long. You don’t think 300m is safe? I am concerned that the P4P is going to take more time getting up to 300m in altitude that actually doing any surveying. My other concern is VLOS. At 300m I doubt I will be able to see the P4P under most light conditions.


#5

Hi Darren,

Thank you for the awesome advice. I work in QGIS, so the planning should not be too much of a hassle. I have imported the contours and created a DEM to get a reasonable idea of where the altitude issues are going to be so I can plan those areas separately.
Your map key and data management ideas sound spot on. I think that is where most of the headaches are going to be when it comes time to process. I suspect that the light conditions are a whole other issue I will have to face later.
Cheers
Matt


#6

Fixed wing drone capable of long duration flight time (we are talking Penguin or Sensefly EB) or find a vendor with a NADIR camera and a Cessna. If your talking about a P4P platform at 400’ your looking at flight times (at the best) of almost 60 hours not counting repositioning and all the line of sight issues with relief and ground objects that come into play. Economies of scale can come into play with an area that large. An aircraft can fly that in a few passes and cover the entire area under relatively the same light conditions and accuracy. With a phantom your looking at multiple days with a varying array of weather and atmospheric conditions that will effect the camera. Also, I’m going out on a limb here, but you do have a computer capable of stitching that all together, processing it (think color mapping, pyramids, etc), and storing it mosaiced along with the original format (think terabyte at least)???


#7

In our region the AGL limit is 400’ or 400’ above that tallest subject structure. I think most places have this regulation so I would check with your area before too much planning. If that is the case then you almost triple your planning flight time.


#8

Hi E_Poole,

I agree, it is going to be a nightmare to store and process. I think fixed-wing or Cessna is the way to go.


#9

Hi Michael,

You are correct. The legislation caps non-licensed pilots at 400ft. Licensed pilots can fly higher but need to obtain permission prior to undertaking any survey at greater altitude. It think this project is crazy. I think you are right, fixed-wing is the way to go.


#10

You should use terrain following drones/planning for this site as the change in height (~700m) is too great.

I would also support other posters recommending the use of a fixed-wing UAV, eg A Delair UX11 with PPK (not RTK).

I would also consider an AGL of 300m to be too high for safety, but if that is the prescribed flying height then VLOS is essential.

Regards
Dave


#11

Hi Saigondave,

I have to agree with you, fixed-wing would be the way to go.


#12

Just thought I’d drop this article into the thread here - 17,000 acre map for the Camp Fire. Detailed write up of the experience.


#13

Hi Adam,

Great article. I see they flew 518 mapping flights. Wow.