AP: Panorama stitcher rotates horizons, preventing accurate merging

[LenC]

I have been trying to make a panorama from a group of pictures shot together that contain a sea-sky straight line horizon. Modifying the source masks as in the video "Tricky Panoramas" has not been helpful, and I realized (and demonstrated) that many individual pictures are rotated, and by different degrees depending on which other pictures they are stitched with. So:

Does anyone have a workaround for this situation? Or a third-party stitcher that does not behave this way?

Or should we ask Serif to add a feature to address this need?

(True, not all my horizons are perfect, but I checked them.)

 

[stokerg]

Hi LenC,

Without seeing the pictures it's hard to see what is happening.  From the sounds of it, Affinity is rotating some of the images to line up with something from the previous image.  If you'd like to upload the images you are using to our Dropbox here i can at least then try to replicate the issue and get an improvement logged with the Dev team if need be.

[LenC]

Tried to upload files, queue kept stopping. I got all 11 prestitching originals up, plus a couple of screen shots on upload status from Dropbox. Flattened the three 60-MB stitched afphotos to 20-MB jpegs, but the Dropbox screen would get to 40% uploaded and quit.  I can try halving the linear dimensions tomorrow or try to upload the files through the forum. You can try stitching these yourselves or wait for a second try. Here's what I was intending to post with the files:

 I have placed the following image files in your Dropbox location:

 

Original 11 unstitched files labeled L1.jpg to L5.jpg (lower row) and U1.jpg to U6.jpg (upper row),

 

Stitched images from lower, upper, and both groups of originals [failed on 9/25/18]

S1 AP-stitched lower group.afphoto/ or jpg

S2 AP-stitched upper group.afphoto

S3 AP-stitched both groups.afphoto

 

Discussion

All stitched files show rotation of horizontal lines and mismatch of details near the horizon. (Horizontal lines and a straight sea-sky horizon are clearest in the leftmost two original images.) The S1 lower row contains shoreline features below the horizon, and the S2 upper group contains sky with clouds above the horizon. It appears that there is more rotation in the group with sky and clouds.

If this is not clear enough I will try to take another series with a clearer horizon, but I do not have immediate access to such a scene.

I attempted to explore an alternative stitching app by downloading Hugin.app from hugin.sourceforge.net. This is free and open source and is complex, and is also aware of projection, rotation and alignment issues. One stitching using default parameters gave an image that was superior in places to the above but not excellent. An attempted repeat led to a dead end that I attribute to not so great documentation of the user interface. If I make progress with this I will add a note to the thread.

[John Rostron]

How much overlap is there between your individual images? Lack of overlap is a common reason for mis-alignment. You should aim for at least 25% overlap between images.

John

[stokerg]

Hi LenC,

Thanks for uploading the files.  As @John Rostron has mentioned, a good amount of overlap between images will always help when stitching panorama images.  While you do have some overlap, it isn't much between pictures and then you have the different exposure levels of the images, again which won't help when trying to stitch images.  Also a tripod would really help as it would keep the horizon straight between images, which will also be why some are rotated as it's trying to line objects up.

Having said all that, i just noticed from the EXIF data these images have been shot on an iPhone, which isn't a problem, i use my iPhone camera a lot when feeling lazy and don't want to carry round all my camera equipment.   Have you tried just using the Pano Option on the camera?  As that should be able to take one long image and no need for stitching  

[mikerofoto]

I do have a pano I can’t get done, around 35% over lapping, a mountain behind the lake and it just won’t align the lake at horizon with trees.

other than that 8 files pano, usually AP does a good job stitching them.

[LenC]

Thanks for your suggestions. I will check the overlap and try to do better. But my pictures are shot in stolen moments while walking with others, so time to compose is rare and a tripod not workable. The iPhone panorama option for seascapes without a tripod can also produce wavy horizons that are beyond my ability to repair. However, the varied exposure issue in wide panoramas such as these seems to be handled well by the AP algorithms.

I try to make up for the limitations of my photos in the evening in AP, so my proposal is: are there some changes in the stitch options that might help users (not just me) make better pictures? My exposure to Hugin has made me realize how many subroutines go into action when one presses the Stitch button. The options available in that program, once one understands it better, include a choice of projections (spherical, cylindrical, architectural, many others), the ability to manually nudge the source images' locations, and the do-not-rotate option that I was originally seeking. Some others seem too specialized for general use. So the developers can ponder if there is enough demand to expose some of the stitcher's workings to the general public. I for one would appreciate it, since I'm not sure that Hugin can repay the investment in learning the GUI.

 

[LenC]

@mikerofoto, can't say much without seeing, but I once fixed an issue by cropping one image before stitching.

[stokerg]

2 hours ago, mikerofoto said:

I do have a pano I can’t get done, around 35% over lapping, a mountain behind the lake and it just won’t align the lake at horizon with trees.

 

I'm on a few days holiday now till Monday and won't be back on the Forums until then.  If you wanted to send an email to affinitysupport@serif.com and send the images in, one of the guys in the office will be able to take a look   It sounds like they would be a good set of example images to log an improvement with the Dev team.

 

2 hours ago, LenC said:

But my pictures are shot in stolen moments while walking with others, so time to compose is rare

I know that situation very well.  I'm always being told to hurry up when out with others as i'm normally trying to setup a shot of something that's caught my eye  One thing i've learnt, a few extra minutes setting up a shot can save a lot of headaches as not everything can be corrected in post, sadly.  

2 hours ago, LenC said:

are there some changes in the stitch options that might help users (not just me) make better pictures? My exposure to Hugin has made me realize how many subroutines go into action when one presses the Stitch button.

I'll have to log an improvement suggestion with the Dev team and if it's okay with you, i can use the images you uploaded as an example and see if they make any adjustments.  I'm glad it's not up to me to do the coding (or any coding for that matter) behind the 'stitch' button, so many variables to account for as every set of images it's processing is different.  Can't say i've used Hugin, but i'll check it out over the next few days and see what results i get.

[LenC]

It's ok to use my images for that purpose. It's interesting how many stitching programs are listed in https://en.wikipedia.org/wiki/Comparison_of_photo_stitching_software and links therein.

And I imagine there are others serving special needs in science and engineering. The Hugin.app is a front end for a large collection of programs that seems to be European in origin but has a large world community that is comfortable with the command line and compile-your-own. The English documentation appears poor, but there are tutorials and perhaps better docs in other languages.

I was unable to run Hugin after the first try, but I expect I can learn enough to do that.

[LenC]

Some tutorials on YouTube.

[LenC]

A bit of history from an extended link crawl on Wikipedia and links therein. There was a proprietary program created ca. 2003-2006 called AutoStitch that automated the process of choosing how to blend the images into a panorama (http://matthewalunbrown.com/autostitch/autostitch.html). It's available from here in free demo versions; there were  commercial Mac versions but the links on the above site say that they are no longer available, one as of this month. However, a license went to Serif and is presumably the ancestor of the AP stitcher. So there must be some Serif people who have an idea if manual intervention in this process can be useful. A commercial license adds capabilities but I can not immediately tell what software is using it.

I downloaded the demo Mac version from the above page, and it worked well on the lower 5 of my images in default mode after adjusting the output size (jpg). The horizons I think are somewhat better than the AP versions, though not perfect. There is a ghost image that would have to be retouched out. The dark shadows were also much improved.