Dear all
We 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
Number of photos: 300-400
Photo taken out before processing: None
Software: Photoscan
Many thanks in advance!
Replies
Hi Keneth thank you. We will. Best
Hi Qan Le,
You can also try to recover your log file directly by extracting the memory card from Pixhawk and read on your computer.
Maybe next time you can increase the overlap of images, i usually do 80% longitudinal and 65% lateral
We are based in Cameroon and may help you for outsourcing, I sent you a friend request to discuss.
Pascal
The second one is missing even more photos, so that's kind of a problem.
I suspect you flew over the area of interest, you should have covered more of the surrounding area too.
I too am surprised over the poor precision, also no elongated/stretched markings in the turns makes me believe you do not have a image skew (wrong picture matched with wrong position)
- how did you match the position ? - by CAM messages ? - why is so many photos missing ? - and are all the rest of perfect, sharp quality ?
hard to say anything more without the material. - but unless camera calibration if very off (like wrong lens), or geodata is mismatched with photos, I am afraid you can't fix it . - maybe improve by setting manual markers in photos, but not fix properly. The missing photos on leftmost part of second location will make that area impossible to stitch. (and calculate DEM at all.)
Hi Andre K
Thank you for your comments - I think they are valid e.g. we did have issue with geotaging. We could find the .tlog so we used Event30 geotagging utility. However there seems to be another geotagging activity with the log file on the Pixhawk autopilot - according to Event38 instruction manual. We couldn't do the second tagging because we couldn't get the log file from the using the microUSB cable.
I need to check with my team before I could respond more fully.
In the mean time, would you be kind enough to repost your reply to this same post under "Agriculture UAVs"?
I just moved the post to "Agriculture UAVs" as I thought it might be more appropriate.
Hi Joe
Yes we do need some help here. We also want to test out your drone data management software. I will email you separately. Best. Quan
Did not find the thread you mentioned. http://diydrones.com/forum/topic/search?q=Agriculture+UAV
It sounds like you tagged from .tlog - that's a big no-no , the position is reported there with extra delay and/or jitter based on the telemetry link , at 10Hz.
Thank you Andre