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
Thank you Jeff,
is your utility exe Ground Control Station / MS Windows run off-line / on-line , since it supports MAVLink, during the flight ?
Does it access done camera's sd card during the flight ?
Sorry for basic question but I would like to set more exif tags for the image, more tags from sensor data.
I am just testing exif read library (js)
Looking for exif write library (js)
to work in off-line mode (batch processing) controlled via html page.
I need to save GCS, RTK data as exif tags.
The utility is an exe which takes as inputs the .tlog from a pixhawk powered vehicle and exports a csv with image names corresponding to GPS tags (lat, lon, alt). It's a PC application which would be run after the flight only.
Hi Cedric,
The area we surveyed was very remote in Africa. Google earth image was very poor.
Impressive accuracies you got there. Have you done a comparison between survey by total station and by drone for engineering design.
Can you say that in most cases you can replace total station and other ground instruments with drone survey? The issue for us is that right now ground surveys take too long due to various challenges of operating in Africa. If we can use drones for engineering survey then that will cut our time in the field significantly.
I am on quan.le@gmx.com for further discussion.
Best. Quan
Many thanks Cedric just a final point before I move to the direct email, if the ground is a mixture of bare ground, glass of different heights, crops and some trees (typical of Africa arable land) the would the accuracy be OK?
We will go through the paper but it looks good.
quan.le@gmx.com
Best
Quan
Hi Cedric
But any wild agriculture land will certainly include all type of vegetation. I guess through post processing/photogrammetry you can correct the distortion created by tall grass and trees?
@Quan,
you can get 1cm GPS accuracy and 1cm resolution with RTK GPS diff and corrections, modern GPS chips can be clocked 1Hz up to 50Hz.
To establish an array of Ground Control Points for a large area ortho surveyed you don't need to spend $Ts.
Mobile Control Point with your drone mount RTK GPS can offer you 1cm GPS accuracy and 1cm GPS resolution.
But going back to your problem.
Your imaginery can still be repaired since image overlap can be used to correct err in alt, step by step (basics of trigonometry) image by image.
Since you are not interested to have your imaginery repaired, I really don't know how could I be of any help.
Hi Darius we will reply with proper GCPs - There are still a lot area to cover.
Best
Quan
Cedric, thanks for sharing. Excellent paper
Thank you for your advice. We think photogrammetry is a specialist skill that is best left to professionals. The flying was fun but we will look to fight people to work with on multiple projects. Best. Quan
Thank you.
Execellent lectures by Cyrill.
Any chance to get pdf version ?
-
1
-
2
-
3
-
4
-
5
of 5 Next