Capturing Long Canals

We have a project coming up which will require surveying approximately 80 miles of canals in South Florida. The goal of our survey is to identify and catalog any wading birds that we observe to create a regional inventory for our client.

These canals are ~75 feet wide on average. Take a look at the attached images…

Should I make these flights one long single transect (first picture) or should I make it so the drone will make multiple passes back and forth (second picture).

We have a DJI P3 Pro. I’ve read that flying at ~250feet is actually ideal when using DD to create aerial imagery or 3d models. What would be a good altitude for flight in this situation? We will be trying to identify species and population numbers of the birds which will be roosting among the mangroves on sides of these canals. Since the goal of these missions will be hi-res pictures that will allow for species identification, shouldn’t I fly at a lower altitude?


So I will give you the advise that I was given for roadway projects and that is to not go directly parallel to the canal. I go at a 45-60 degree angle to the centerline of the roadways and have had great results.

Hey @Dylan_Ayers,

congratulations on such a sweet gig! SO to piggy back on what @dragonflyAS has mentioned, you will want to fly at an angle not parallel to the canals, a 30-60 range should work nicely. There are a couple of reasons for this; it will allow you to capture better the edges of the canal where parallel travel will loose some data there, this will also increase the amount of data points you get that are outside of your desired area (in this case the canal) this is important for the software to be able to create accurate tie points, and will help to increase the local accuracy (resolution) of the map. Make sure you are flying more than just the 75 feet width of the canals.

As to the height this is counter intuitive, you might think the closer i am the better detail i can capture in a photo, and for a single photo this may be true, however you have to remember that a key point of producing high quality and superb definition orthos is the ability of the software to find and coordinate tie points to stitch the images together. So you will find there is a balance here, the lower you fly the more detail in one picture, however since you are actually capturing a smaller area in the photo you are getting less data for the software to use, which will lower the accuracy. On the other hand if you fly higher you will be capturing more data in each photo for the software to be able to create more tie points. This will lead to an overall better map quality ( i would suggest running some test runs to find the best mix of detail and data for your needs.)

Also since you are talking a very large, if not just long, project make sure you are breaking the entire project into an organized system, (section A- map A1, etc) this will allow for easier organization and file management. and make sure your mapped sections have some overlay so they can be tied together.

Scott Lashmit

Have you tried flying at survey height over wading birds that are visible to you as you fly? I suspect they will be very hard to see from above. I have had to look for eggs in nests and that was tricky but had the advantage of the target being bright (ish)

Thanks for the advice!

This is definitely something we are thinking about. If you’ve ever seen a rookery with birds nesting (in FL), you’ll know that they are actually very visible, especially lighter colored specimens, (snowy egret, spoonbills, ibis…)

The birds sit atop the vegetation and build their nests towards the “outside” of the mangroves. We will not be counting eggs, we are looking only for species type and numbers. With previous tests of the drone, we have been able to take some pretty high-res photos that allowed us to do some plant identification from ~200ft in the air…I think we will be flying lower for this project.

I have flown missions out in the swamp here in South Florida and fly about 200 to 250 and can easily see the birds below. I would probably say 200 foot agl would be a good altitude. All you can do is run the mission at a angle as the other folks have said and see how it looks. Just have some batteries on hand to run the same mission say at a different alt to cover you. Of course going out and shooting a few different single photos at different heights can be done also with instant information before running the full mission. Best of luck I am sure you wont have an issue.

We have an endangered bird here and if there are two eggs on a nest one egg is removed and incubated elsewhere. Previously folks had to wade out to the nest to look. This is quicker and less intrusive. Best of luck with your work.

Hi Dylan. I sent a message to you. Could you check your box?


I have jus completed filming a small section of pipeline, not that different from your project. I tried flying it it to different configurations. The first was up and down the line parallel with the route and the second I did two flights for each section at 45 degrees to the line such that that two flights are at 90 to each other. Both were flown at 250ft. The later, whilst taking a lot longer produced a far better result. Generally I planned the flights to optimise flight time allowing room for safety. In my case I was looking for good resolution plus I needed accuracy as I was using ground control points.

A big job - hope you have a lot of batteries!!