# Linear Scanning - Roads / Gas Pipelines

I have a job to create a 300-kilometer pipeline orthophoto. It will accompany a highway and I believe the dronedeploy mapping app is not able to help me. I thought of using the native DJI software in the follow-me function for this scanning process. How much should I set up the photos overlap? How to calculate the projection in solo of the photos flying a P3-pro to 100, 150 or 200 meters? Can the dronedeploy software calculate the orthophoto with only 1 pass or should I make 2 passes? Help is welcome.

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WOW! What a great opportunity!
I would think that DD would be able to help you, what makes you think otherwise?
It obviously wouldnâ€™t be able to complete the entire length in one shot, but in smaller sections it would be fine.
If it were me, I would conduct a trial-run of the right-of-way (1000m length or so) at a 45Âş angle across its width, with 75-80% overlap at 100m AGL and see how that works.
Hereâ€™s a similar, linear project:

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What is the accuracy and precision level requirement? (How close to real-world coordinates and how fine a resolution do you need) The accuracy requirement will drive how many GCPâ€™s you will need. I always go with at least 5 per flight, more if convenient, plus at least two or 3 check points so you can check your true accuracy and can prove it.
The precision spec will drive the GSD (Ground Sample Distance) which will determine your flight height. Iâ€™ve been doing linear type surveys with at least 3 flight lines - one down the middle and one along each side - more if it a wider swath. I use 85% forward overlap and 65% which is good enough for generating a 3d model as well as orthophoto.
Sounds like an awesome project - Iâ€™m seriously jealous!

Diogod, That sounds like a really cool project. I will offer some suggestions to you as I am finishing up a 250 mile storm water drainage project for a local city department.

I am assuming you will have trees and ground cover in many sections of your run just like I do. For my project, I set up flights in areas of heavy vegetation at 300 ft. altitude with a 75/75 overlap. DD flight planning is used most of the time but every once in a while, I will have runs that turn and twist in such a way that the flight plan ends up mapping a lot of area that is not needed. This is usually in clear open areas so I use Litchi to plan a linear flight that provides at least three passes (100 ft.between lines) and the map comes out great.

Good luck on the project and keep us updated.

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We just released a Linear Flight Planning beta app on our app market. This is specially designed to map thin and long areas of interest. Try the app and let us know what you think of it.

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Hi Manu,
I had tried to use your app with no success. I cannot activate the app. Any ideas?

Regards,
Felipe

Hello, can you give brief steps on how to go about planning a linear mission as per the above? I canâ€™t get it to work at allâ€¦Thanks

Where are you getting stuck? I created a GIF on how to use the app, you can checkout here: https://www.dropbox.com/s/g1ws9dnccdpn97p/linearmapping2.gif?dl=0

Here are screenshots:

1. Create a plan and open Linear Mapping app

2. Inside Linear Mapping app, turn ON the toggle, and click YES on the toast

3. Edit the geometry as you see fit to cover a linear area of interest

Note: After this plan is synced to your mobile device, you will see edited geomtery with no linear flight plans by default. You need to just turn ON the toggle on mobile device to create linear flight paths to already edited geometry.

Thanksâ€¦I canâ€™t seem to get it to work on our usual Samsung note , Lenovo table (both android), and my desktop. Oddly enough it works on my windows laptopâ€¦Nonetheless, when the mission was saved on that laptop, using the android to open the mission and fly it failsâ€¦So Iâ€™m not quite sure whatâ€™s happeningâ€¦

p.s the dialog â€śAllow linear mapping to modifyâ€¦â€ť does not come up on our android tabs and desktop, it does on the laptopâ€¦

Thanks

Hi Manu, the app is stuck at " Allow Linear Mapping to Modify Waypoints", since this prompt does not come up on some tablets and a â€śYESâ€ť is expectedâ€¦I suggest skipping this prompt altogetherâ€¦

Hi Manu,

Thanks for the message and the effort in producing the gif file.

At the begining I had problems in running the app. The App white pop up window never appeared after clicking on the App button to activate the App in my laptop running Win 7 and using Opera. I fix this with help of DD people by unblocking the site â€śamazonawsâ€ť (or something like that) in the browser location services settings.

Now that I had a successful flight and nice images, DD doesnâ€™t compile the 2D map: After uploading the photos I did change and update the survey area before postprocessing. The resulting 2D map do not consider the updated area, only a straight line.

Below an image with the resulting 2D map and in red the intended survey area.

Inline image 1

Any ideas?

Regards,
Felipe

Hi @Felipe can you send me the link to the map so I can investigate?

@ard thanks for the feedback, I will incorporate this in our next version which may be in a week or so.

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@manu, Just click the link below:
http://drdp.ly/QnNz3u

Felipe

@Felipe we are reprocessing your map with relaxed crop geometry. I think the problem was that the initial geometry you chose during upload was quite tight.

Hi Manu, any update on this?

Thanks

@ard here is the map I processed with default boundaries: http://drdp.ly/PR66vg