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Photoshop is really bad at stitching

 
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perdu34



Joined: 25 Nov 2016
Posts: 50

PostPosted: Thu Aug 02, 2018 6:23 am    Post subject: Photoshop is really bad at stitching Reply with quote

Just for fun I loaded my latest stack and stitch into Photoshop to see how it would cope.

So far, there are 230 tiles covering this beetle. Once finished it will be a ~600 megapixel image.

The alignment took just over 90min on a 2013 MacPro with 6-cores, 16GB of ram and a 2TB scratch drive. Photo alignment is a single core process in Photoshop CC so cheaper, but newer I7 would have done it faster. The scratch drive is just an old empty USB3 hard drive so not to use the internal 500GB SSD.

Here are the results:

Yes, this is a 10GB image Smile

As you can see its bad, really, really bad. Almost comically bad.

Lightroom does a MUCH better job of aligning and blending the images, but has size limitations.




Another week and I should have finished imaging the legs and it will be just the editing left to do.
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JohnyM



Joined: 24 Dec 2013
Posts: 360

PostPosted: Thu Aug 02, 2018 11:31 am    Post subject: Reply with quote

I wouldnt even touch that large panorama without telecentric optics.
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perdu34



Joined: 25 Nov 2016
Posts: 50

PostPosted: Thu Aug 02, 2018 12:42 pm    Post subject: Reply with quote

JohnyM wrote:
I wouldnt even touch that large panorama without telecentric optics.


Thanks for your vote of confidence. It really is these little bites of encouragement that keep forums alive.
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JohnyM



Joined: 24 Dec 2013
Posts: 360

PostPosted: Thu Aug 02, 2018 12:50 pm    Post subject: Reply with quote

Dont get me wrong, i dont mean to discourage you. Actually i evny your patience to put enourmous amount of time that this kind of work requires.

Seeing how much distortion is present in the image and comparing it to my results, i suspect your lens is quite far from telecentric, therefore making this kind of project very challenging. I would dare to say - impossible - for me, as i cannot spend that much time on manually stiching the images.

Can you check your stacking software alignment and scaling parameters log? Just curious.
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 19326
Location: Richland, Washington State, USA

PostPosted: Thu Aug 02, 2018 12:54 pm    Post subject: Reply with quote

perdu34, I confess that I'm curious about your motivation for doing this particular piece of work.

I have seen several people go to a lot of trouble to make huge pixel count stack-and-stitch images of insects.

In some cases the goal is to make wall-sized artwork that can be viewed arbitrarily closely and still look good. I can easily understand that.

But those cases also involve perfect specimens and lots of attention to all the other aspects that make spectacular art.

None of that seems to be the case here, so I'm curious.

I get the vague feeling that maybe you're developing technique that will eventually be used for something else, but I have no idea what that might be.

Is this an aspect that you're able to talk about?

--Rik
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JohnyM



Joined: 24 Dec 2013
Posts: 360

PostPosted: Thu Aug 02, 2018 1:05 pm    Post subject: Reply with quote

My comment was coming from my experience.
I've used Mp-E65 on FF to get images like this:


Those are 500 megapixels (analyzing software limit) panoramas of prepared samples. About 15 fields of 10 slices deep stacks. Automatically aligned images in photoshop resulted in 3 "sub" panoramas, that i had to manually stich while using warp distortion.

Only after producing final image, i've noticed that it's full of small errors like this:
top of image


bottom of image


I've stacked just ~10 images per FOV of very flat subject. Insect like specimens i wouldnt attempt anything bigger than 2x2 FOV. Maybe 3x3 if i could find a good reason to spend time on it (im often printing 150cm x 100cm 150 ppi from single A7RII FOV and find results quite satisfactionary).

Hence my recent interest with telecentric lenses, that i struggle to understand. Maybe it's a good idea for you too.
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Beatsy



Joined: 05 Jul 2013
Posts: 1391
Location: Malvern, UK

PostPosted: Thu Aug 02, 2018 4:42 pm    Post subject: Reply with quote

I've done this too. In my case, it was expending infeasible amounts of time and effort to produce a 30k-pixel square image of a 2mm diameter diatom arrangement I'd made. Stack and stitch with a 10x Plan APO objective. Sure, I could zoom in and see striae and even punctae on individual diatoms. But in showing it to the world, I posted a 1k square image first, followed by an A1 print for an exhibition (an exception, not what I ever planned to do).

In both cases, I put FAR too much effort into producing the original image in comparison to the output resolution that was actually needed.

But! Big but! It was still a very useful learning experience. Now I tend to consider what I'm going to do with the image in order to "balance" the effort put into capturing it. Not what I *may* do - what I *will* do. The only reason I do that now though is because I learned "the hard way" for myself, not because I listened to those who pointed out my wasted effort.

I wouldn't have it any other way. Lessons experienced are infinitely more effective than lessons dictated IMO! With the former, you can incorporate your own desires and proclivities - and sometimes produce something far beyond what is considered possible by accepted wisdom. Go for it!
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elf



Joined: 18 Nov 2007
Posts: 1356

PostPosted: Thu Aug 02, 2018 5:13 pm    Post subject: Reply with quote

Orthographic stitches are almost impossible to do without either distorting the subject or having stitching artifacts.

In my opinion, the only good methods to make large panoramas are by rotating the lens/camera around the entrance pupil or using a telecentric lens.

That being said, try Autopano Pro or Microsoft ICE for orthographic stitching. Both will be significantly better than Photoshop.
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