Missing Part of an Image

Hi,

I need some help understanding why part of an image is missing. I uploaded 646 images but it only appears that about half of the images were stitched. Using two different data sets from two different drones gave me the same results. Why would part of the image not process?

Thanks for your help.

Anthony.

1 Like

Hi Anthony, sorry for the trouble. Forests are some of the most difficult landscapes.

This could be lots of factors, but sharing your settings used, frontlap and sidelap, platform (camera), flight height, and your photos if you are able to share them will help us troubleshoot.

1 Like

smathermather,

I can start with my settings:

First Data Set
Platform: Autel EVO II Pro 6K
Altitude: 250 feet
Speed: 5mph
Front Overlap 80%
Side Overlap 70%

Second Data Set
Platform: Phantom 4 Pro V2
Altitude: 250 feet
Speed: 17.3 mph
Front Overlap:80%
Side Overlap: 70%

I am in the process of uploading the images from both data sets to share with you. I will post a link here for you. It will be awhile for the upload to complete.

Here is the link to the Autel Data Set. There are 637 images. Still uploading but here is the link.

https://drive.google.com/drive/folders/1lNGEA1fDu2m-dVp44Rlj6kdPEFxmxeGg?usp=sharing

Here is the P4Pv2 Data Set link. There are 431 images. Again, still uploading but here is the link for when complete.

https://drive.google.com/drive/folders/1Svh8XWKftWEgkMF-BwbJn-Z5JBQ8KBiX?usp=sharing

Thanks!

1 Like

Excellent! Thank you. 70% side is problematic over forest – minimum over forest might need to be something closer to 75%, especially flying that low. But, with some extra feature extraction and maybe some other tweaks, we might be able to get something suitable from the dataset.

Do you need just orthos or elevation data as well?

1 Like

Just Orthos. I generally have not had a problem with these settings before. But interestingly enough, the part that is missing has a road so it should be easy for the system to stitch, I would think. By the way, The same problem happened with the 350 foot altitude. Same part of the image missing. You want me to upload those too?

1 Like

Hmm. Sure: you might have outrageously good overlap with both. :smiley:

1 Like

Agreed! I worked with 4 data sets. The Autel at 250 feet, and the P4Pv2 at 250, 300 and 350 feet. All 4 orthos are are missing the image in the same area. Strange!

1 Like

Ah, upload them all. Let’s figure out what works.

I used to work in parks and I got super frustrated with forests and just stopped flying them at less than 77% because most of the time 75 or less worked, but 77% was a guarantee of a good result and worth the time/predictability trade-off.

But: software has improved since then, and so we’ve got more tools to throw at this than then.

1 Like

OK, the 250, 300 and 350 will be in the P4Pv2 folder. Looks to be about 4 hours before upload is complete. I will catch in a day or so?

1 Like

Sounds good. I’ll have somewhat slow internet over the end of the week and weekend, so I might not get to it until early next week, but happy to take a look if I get to sooner.

1 Like

I appreciate it. Thanks!

2 Likes

Just as a test I am trying a new project with the images (Autel Data Set) from the area that is missing from the first image. I want to see if the system errors.

2 Likes

I had to verify the capture locations of the images so there aren’t any missing tiles. So I am stumped how 4 data sets from two different drones is exhibiting this type of output from the server.

1 Like

70% side lap in all the datasets is the explanatory variable — that is low for forest. That said: I can’t really say for sure until I see the data. :slight_smile:

1 Like

The entire data set is at the links Stephen. Thanks!

2 Likes

Stephen,

I went back today and took another data set. Changed the settings to 80/80 @ 330 feet and the same thing is happening. So it is not the overlap that is an issue. I just do not understand why the system is overlooking parts of the image.

1 Like

We must be lacking detail there for one reason or another. What’s your shutter speed vs airspeed? Did you try with rolling shutter correction on?

1 Like

If these are the data you are direct uploading, you’ll need to fix your filenames from different flights from overwriting each other. I’ve only checked one of the datasets, but it looks like you might have duplicate filenames.

If you need help renaming files, do a quick search on these forums for fixing duplicate filenames. There are a few different approaches. If this is the issue and you find the solution, post back here about what you did to fix it. If this doesn’t fix it, I can dig deeper.

1 Like

Stephen,

I am not sure what you are looking at that you see duplicate file names, but each data set is its own entity. Lets just work with one data set for now. It contains images 1 through 637. There are no duplicates. If I upload all those images, it leaves off the whole top portion of the map.

To answer Saiins question. It was flown at 250 feet at 4.5mph, shutter speed is 1/200 at f/5.6. The Autel has a mechanical rolling shutter which I do not believe can be turned off. However, I also flew three data sets with a Phantom 4 Pro V2 which has a mechanical shutter at the same altitude. Camera settings were the same. I also collected a data set with the P4Pv2 at 300 and 350 feet and same camera settings. Results were the same on the map output. The top half does not get stitched. It is as if the server just overlooks the images from that area. Interestingly enough, If I just upload the missing section, the server stitches them. But why does it not include them when I upload the 637 image job?
I never had this problem before. Normally, I just upload the images and everything gets stitched.

1 Like

Hmm, 431 is what I get in the second dataset without duplicates. I’m not sure what happened with the zip I downloaded from Google. I am currently starting a test with that one not the larger 637. It is usually better to test with smaller datasets exhibiting the same symptoms for faster iterations

Now running on defaults. Out of curiosity (as I don’t think this has been addressed yet), what are your settings, and have you run this with default settings to any effect yet?

1 Like