We (www.gmxconsulting.co.uk) are developing a large-scale agriculture project in Nigeria (5,000ha) and started to use drones to survey and map topography.
The intention was then to use the Digital Elevation Model for irrigation planning and design. However, when we post processed the images we got very large x y z errors - please see the photos below.
1. Could anyone tell us where we have done wrong? Can we correct NOW (after the aerial survey)?
2. Also we look to outsource the drone surveying and post processing for our projects in Africa - Anyone interested please let us know.
Here are some more details:
Platform: E384
AGL: 120 - 180m
Overlap: Front 60% Side 60%
GCPs: No
Flight time: <60 mins
Cameras: Canon S110 RGB and NGB
Number of photos: 300-400
Photo taken out before processing: None
Software: Photoscan
Many thanks in advance!
Replies
Hi Qan Le,
You can also try to recover your log file directly by extracting the memory card from Pixhawk and read it on your computer.
Maybe next time you can increase the overlap of images, we usually do 80% longitudinal and 65% lateral. CGP will also greatly help. All said above already.
We are a land / sea / aerial survey company based in Cameroon and Nigeria, and may help you for outsourcing, I sent you a friend request to discuss.
Pascal
Hi Pascal
Sure, we took the Pixhawk memory card with us back to London (the drone still in Nigeria). It's good to know that you near where we are. Let's talk.
Best, Quan
Hi Quan,
one question - the change in alt was during the flight? if so way was it?
it looks like this is the reason for the big elevation inaccuracy.
if you have limitation to do the whole flight at 120m the do it in 180 the deference in the ground resolution is not that big of deference and I think that`s where the problem is located. we have done several vineyard mapping on topography called "running hills" whit no change of the altitude with grate successes
as for the GCPs you need it only if you want to "anchor" the orthopoto to the world if an accuracy of 2-3 m is OK you can use the UAV GPS.
feel free to contact me by mail would love t help you with your project.
have a great year
Benny
bennys@agrimapic.com
Hi Benny
The first flight was at 180m and second at 120m AGL. They were entirely autonomous so I am not sure how the change in AGL affected the accuracy. Anyway for irrigation planning and we need accurate in the cm. It is actually not difficult for us to get a few GCPs. We just need to plan better next time.
For UAV surveys the key outputs we need for irrigation planning and design are:
- contour map with x y z at scale of 1:500
- orthophoto
As we are designing, developing and managing agriculture projects in Africa we would like to partner with UAV surveyor, companies or individuals. Our projects are generally >1000 ha.
Please could you send a proposal and some example of your work to quan.le@gmx.com ?
Best,
Quan
Quan if you fly in South Africa and shortly all the SADC countries you better make sure you are legal. Jail time otherwise.http://www.safedrone.co.za/
@Gary,
South Africa and Hobby Drone
http://www.safedrone.co.za/hobby-drone-pilots
Hi Gary
Excluding South Africa, it takes about an hour to get clearance with the local Aviation Departments in the respective countries....we have been there and done it!
Regards
Michael
Sure Gary - One of the reasons why we want to outsource the flying. It was fun but apart from the licensing issue, we would rather focus on the actionable insights - we are ag developer and manager, not drone surveyor.
Thanks again for your advice earlier.
Best, Quan
Hi Quan,
Would be very much interested in discussing the opportunity of undertaking the Data Collection and Data Processing as per your requirement. We have gained a lot of experience in mapping large areas at a very rapid pace. We are using custom built UAVs with two hours endurance and can carry 1kg of payload. We are able to map upto 4400 Hectares area in a single day with 3.5cm/px for RGB and 10cm/px for Multispectral Camera. Plus the UAV being indigenous, we can get the work done in very affordable cost. The accuracy achieved by use of GCPs is upto 10cm. We are also working on the RTK systems to reduce the efforts of GCPs.
Please contact me at pravinp404@gmail.com
Sounds great Pravin. For UAV surveys the key outputs we need for irrigation planning and design are:
- contour map with x y z at scale of 1:500
- orthophoto
As we are designing, developing and managing agriculture projects in Africa we would like to partner with UAV surveyor, companies or individuals. Our projects are generally >1000 ha.
Please could you send a proposal and some example of your work to quan.le@gmx.com
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