Problems Aligning photos
Hello,
For some reason, the last several flights I have taken have produced images that won't align in WebOEM or Agisoft Metashape. I'm using a Mavic 2 Pro. I'm pulling my hair out because this is for my master's project, and it's been discouraging because I've gone out several times to my project site and still have come short of an orthomosaic.
I'm not getting gimble errors and I have tried my flights with and without terrain follow. Here are the last two flights I did this week and an image showing how screwed up this is. Anyone know what this could be?
Comments
21 comments
The Dronelink flight looks OK to me which means the most likely scenario is that you are having trouble in the stitching
A few things that occur.
First, trees are notoriously difficult to do in the first place because they are just so similar. But...it should still be possible.
Did you do anything to the photos first? One of the best ways to stitch similar photos is to use geotagging to locate them in the first place, if you somehow processed them into new files that removed the geotag data you are making life difficult for the program.
If you can - send a link with the photos so we can take a look at those too.
Barry, thanks for looking into my request. Here is the box link to all of my photos that I've taken. I didn't do anything to the photos. They were originally shot in DNG format but the last two flights were in JPG because a friend told me that would be an easier format to process them. I didn't alter the photos - just gave them to two friends who had trouble aligning them.. I don't do/haven't done backend processing.
https://oregonstate.box.com/s/rnke8po14zbkbo42s8pi6k31enoby2o2
Thanks. I'll take a look but I'm a bit backed up at the moment so give me some time. If others get to it ahead of me - great!
No worries - thanks for even trying it out. Let me know if the link works fine.
Link to the images worked fine. One image set (597-617) failed to process in 3dfZephyr but the other set went through to a 3d model with 18 of 20 images used by the software.
That's a real tough scenario to do though - lots of trees.
Hey Ken, sorry I'm not privy to what you said by 18 of 20 images used by the software. What do you mean?
Yeah, it's been a royal pain in the ass but I really see some value for field Foresters to use drones to map their units before getting on the ground data.
2 images failed to align is my interpretation. You can run it yourself using the free version of 3dfZephyr available here:
https://www.3dflow.net/3df-zephyr-free/
Cody Bentley
What were your exposure settings? A lot of these images (in the 50a_5-11-22 data set) are badly over exposed which I don't think is helping your situation at all. Here's an example:
Yeah I saw that - I had it on auto. If you check Unit 41a, they should be better.
Ken Kroeker This has inspired me to learn - i downloaded the free trial. Thank you for the suggestion. The 50 cap on pictures is no good because Most of thse units are over 200 photos but it's better than nothing if I can get it to work.
Cody Bentley
The Unit 41a are better but still badly over-exposed IMHO. If anything you are better off slightly under-exposing - I tend to set my camera to -.03ev.
I would take a good look at your settings before the next capture as I don't think you are setting the camera up correctly - the Mavic 2 pro is capable of much better results than this.
Barry Houldsworth Hi Barry, how do you set the camera to -0.3ev. Any resources you recommend I look at? Is this in the DJI app or dronelink?
Add this as a component before the map
https://app.dronelink.com/barry-houldsworth/components/component/OyMTDPqanckKtIj51Dhe/ez429Bt3bL11qZxZdGL4
Cody Bentley
I processed this last night using the most current version of WebODM desktop - and your 41a data set and it worked fine.
You can download the assets here: https://www.dropbox.com/s/ylvted4s04fi8qs/Santiam-Highway-5-11-2022-all.zip?dl=0
If you run it again please be sure to adjust the exposure settings.
Ahhhh I have the same problem and I managed to solve it in some simple ways So let me share my experince.
I am guessing you are using the mapping feature so here it goes.
+ For the out of place alignment
Make sure that you have high GPS signal. A lot of the time, when you have low GPS signal, this will happened. I don't know why but I wait until I have like 15 GPS signal before start the mission. For me, I wait like additional 3 to 5 minutes after starting the drone before starting the mission.
+Align photos solution
You are taking a forest picture, I too had this problem. The only solution I have for you is to take more pictures. It works for me. I know mapping takes pictures automatically but do you know you can take the picture yourself while the mission is going on?
The problem here is for places like forest, Agisoft fails to find a reference point when aligning the picture, so your solution is take picture in between the intervals of the software taking the pictures. I hope Dronelink will allow us to adjust the the intervals to take the picture like say take 1 picture per second. It works well for me.
Hope this helps. I know I am not a tech savy and English is not my first language. Please forgive me if you do not understand. I will try explain it better if there is any confusion.
Barry Houldsworth Thanks again for all of your help - do you mind if I use that ortho/report in my project write-up? That looks really good. Also, does this flight look good (with your camera settings)?
https://app.dronelink.com/cody-bentley/my-first-project/plan/6mn1Fg76B8C2mj0y2gOW/ug5iVtANb8gMZ6YBaj4m
TarzanEng Thanks for chiming in - I usually have 14-16 satellites when flying. I did not know I could take pictures while flying.. What I am going to do next flight is the flight mission I posted above. I am going to try out the grid pattern. I am limited by battery (i only have 3) but this might help. Your English is good - thanks for helping!
Hi Cody
I will wait until 23 but 16 satellite signal is pretty good. (I should clarify, I have 15 signals when I start the mission but when it flew to the starting point, it will already have 23)
I am not sure the grid pattern helps but I find it far more effective to just press the button when taking pictures. As you mentioned yourself, you only have three batteries so I guess that might be an issue as well.
I already posted in other discussion topic about to take more pictures during mapping mission. I hope I can get it resolved soon.
Out of curiosity, what is you drone? Mine is DJI Mini Mavic 2, just for reference.
EDIT: Oh, yours is Mavic 2 Pro. Nice drone. Sorry, it just skip my mind XD
TarzanEng No worries! I'm actually borrowing it from a professor. When it works out, drones are fun. When it doesn't, which has seemed to be a majority of this project because of my own mess-ups, it's really frustrating. I have a few flights planned so hopefully it works better!
Cody Bentley
No problem with you using that in your project - I hope it helps.
The mission looks good to me - you probably don't need the video parts of the component, but it shouldn't hurt either.
The only thing I would suggest is that you change the FOV of the drone from HQ to Full FOV - that will significantly reduce the amount of the flight time and the number of pictures it takes, but should still give comparable results.
Barry Houldsworth
Can you explain the difference? What is FOV? (Field of View?)
Cody Bentley
Yes, it's Field of View. HQ is basically zooming in - if you have the drone start it up and switch between the different settings, you will quickly see the differenct.
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