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Doing Panos with film shots.
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PostPosted: Sun Aug 07, 2011 5:00 pm    Post subject: Doing Panos with film shots. Reply with quote
Is CS4 photomerge any good as my pano from two film shots looks odd

1st shot


2nd shot


cs4 photomerge


PostPosted: Sun Aug 07, 2011 7:15 pm    Post subject: Reply with quote
There are a number of settings in CS4 to adjust how the photos merge. It looks like you set it on auto, which I find is the best way to do it as it gives the algorithm greater independence to evaluate the images. Here's what's happened with your shots:

1- The DoF is pretty large due to the lens being fairly wide-angle. So right away CS4 is going to try and reconcile that to a flatter DoF, resulting in image warping. This is what CS4 is supposed to do for photomerge, actually.

2- The shots capture quite a bit of terrain in just two images. Similar to above, this will result in warping as CS4 works to make the image flat.

3- Try cropping the image to get a rectangle. It will look a bit like a fisheye photo, which could be a neat effect.

I've been experimenting a LOT with photomerge to learn how CS4 works. And I've had some okay results and a whole lot of far-from-okay results. In general, using six images is a pretty good number. I once used 40, but the photo was way too big and it took eight hours for my PC to merge them all. Anyway, I am also trying to do more over-and-down photos meaning that the final image is a bite more like a single image. For instance, imagine the scene below show with a 55mm lens, two shots down and three across. There would likely be less image distortion.

However, your Photoshop is doing exactly what its supposed to and, as you can see in the middle of the picture, the main focus point is less distorted.

Not a shabby first attempt.


PostPosted: Sun Aug 07, 2011 7:34 pm    Post subject: Reply with quote
Thanks for replying....... it seems the results are never going to be any good with just two images unless I have plenty of overlap either side of the subject and then crop.......might try again with more images but it seems using film for panos is as useful as a chocolate teapot.


PostPosted: Sun Aug 07, 2011 7:57 pm    Post subject: Reply with quote
I did think about to make panos from 6x9 slides , but I did give up. Digital just fine, easy and less costly.


PostPosted: Sun Aug 07, 2011 8:24 pm    Post subject: Reply with quote
Quote:
but it seems using film for panos is as useful as a chocolate teapot

Laughing Laughing Laughing


I am not sure about that. I am doubting because I see on this forum how you guys do incredible stuff on film and it has for sure many advantages compared to digital.

If I would do pano with film (and I was thinking a lot about it) I would
- get a Linhof Technorama
- or only shoot with film when I am doing a outstanding scene ...

so I would practise as much as possible digital pano shooting, that one can rely 100% on the gained skills when it just comes to that magic moment shooting a pano scen with the film camera ...

that's mainly my idea about analog/digital pano

Cheers
Tobias


PostPosted: Sun Aug 07, 2011 8:24 pm    Post subject: Reply with quote
To me it looks as though there's some weird distortion going on in the unmerged pictures, before CS4 tried to merge them. Look at the buildings in the 2nd shot - some of lean to the left but what looks like a castle tower is leaning to the right. And compare the left side of the tiled roof in the foreground - it looks very different in the two shots. Can you work out what's happening?

I'm guessing these shots were hand-held? The 2nd one seems to be out of level quite a bit. Maybe it would help if you straightened them up and got rid of some of the distortion before merging? Just a thought.


PostPosted: Sun Aug 07, 2011 9:03 pm    Post subject: Reply with quote
peterqd wrote:
To me it looks as though there's some weird distortion going on in the unmerged pictures, before CS4 tried to merge them. Look at the buildings in the 2nd shot - some of lean to the left but what looks like a castle tower is leaning to the right. And compare the left side of the tiled roof in the foreground - it looks very different in the two shots. Can you work out what's happening?

I'm guessing these shots were hand-held? The 2nd one seems to be out of level quite a bit. Maybe it would help if you straightened them up and got rid of some of the distortion before merging? Just a thought.


Indeed hand held and didn't think of panos at the time so I assume in the 2nd shot the camera was pointing down more, but the leaning building seems to be a leaning building as in this shot (the lens was a Hexanon 28mm so it should be ok), and the first two shots were taken roughly by the red arrow.


PostPosted: Sun Aug 07, 2011 9:19 pm    Post subject: Reply with quote
tobbsman wrote:


so I would practise as much as possible digital pano shooting, that one can rely 100% on the gained skills when it just comes to that magic moment shooting a pano scen with the film camera ...

that's mainly my idea about analog/digital pano

Cheers
Tobias


Well I suppose I could use my 5mp Sony Cybershot Laughing but I'll have another go with 35mm film and try six shots, and if I can get as good as you will use the RB67 (that gives 10 shots).


PostPosted: Sun Aug 07, 2011 9:38 pm    Post subject: Reply with quote
Getting undistorted panos from two film shots is totally doable. Here is one I did from two film negatives on 120:



I had to trim a small bit off the top, the horizon on the left half was slightly higher, and also a bit off the bottom right. However, I was able to retain about 85% of the image. Capturing stitched photos with wild DoFs that include both close and far objects can be done with multiple photos, but a stitch can be done with as few as two photos.


PostPosted: Sun Aug 07, 2011 10:54 pm    Post subject: Reply with quote
David wrote:
Getting undistorted panos from two film shots is totally doable. Here is one I did from two film negatives on 120:

I had to trim a small bit off the top, the horizon on the left half was slightly higher, and also a bit off the bottom right. However, I was able to retain about 85% of the image. Capturing stitched photos with wild DoFs that include both close and far objects can be done with multiple photos, but a stitch can be done with as few as two photos.



Well it was your thread that persuaded me to do my two shot pano, but I didn't want to jump into your thread.



PostPosted: Mon Aug 08, 2011 6:19 am    Post subject: Reply with quote
Regarding panos and stitching, I don't understand the difference about film versus digital and why it would be different or more complicated using film. I mean, it's digital anyway, the film is just a different sensor technology but at the end you have digital images that you stitch using the same software, and this software does not care about sensor technology.

Or do I miss something specific about film?


PostPosted: Mon Aug 08, 2011 7:44 am    Post subject: Reply with quote
ylyad wrote:
Regarding panos and stitching, I don't understand the difference about film versus digital and why it would be different or more complicated using film. I mean, it's digital anyway, the film is just a different sensor technology but at the end you have digital images that you stitch using the same software, and this software does not care about sensor technology.

Or do I miss something specific about film?


Well only if you think film looks better than digital e.g. B/W or slides, but it's down to convenience and economics, to get near to the quality of a VG DSLR with 35mm film (for a say an excellent pano print) I would have to have each neg for a pano drum scanned, and that is expensive. But as Tobbsman has mentioned using the muscle of a large neg (medium format) is the way to go, but for a computer screen 35mm film might put up a good show using a home scanner compared to digital, but home scanning is boring and the cheapest cost for thirty six, 35mm shots (inc a lucky buy of film on the bay) is about £4.


PostPosted: Mon Aug 08, 2011 3:09 pm    Post subject: Reply with quote
David wrote:
However, your Photoshop is doing exactly what its supposed to and, as you can see in the middle of the picture, the main focus point is less distorted.
peterqd wrote:
To me it looks as though there's some weird distortion going on in the unmerged pictures, before CS4 tried to merge them.
Make sure you don't confuse "distortion" with "perspective" or "projection". Wink


Excalibur wrote:
it seems the results are never going to be any good with just two images unless I have plenty of overlap either side of the subject and then crop.......
Not so! I've shot plenty of two-image panoramas. In general, 1/4 to 1/3 overlap will give the best results, but in a pinch, I've stitched some with as little as 5-6 pixels of overlap. Shocked


peterqd wrote:
I'm guessing these shots were hand-held? The 2nd one seems to be out of level quite a bit. Maybe it would help if you straightened them up and got rid of some of the distortion before merging? Just a thought.

Don't do that!! The panorama stitchers (the *good* ones, at least, so perhaps not Photoshop Wink) rely on receiving unaltered images. They can then automatically calculate and correct a whole set of lens parameters, including lens distortion (simple and complex), field-of-view, projection (fisheye, equirectangular, etc), vignetting, decentering, etc, etc, etc. If you pre-correct an image, it will confuse the stitching software. Wink


ylyad wrote:
Regarding panos and stitching, I don't understand the difference about film versus digital and why it would be different or more complicated using film. I mean, it's digital anyway, the film is just a different sensor technology but at the end you have digital images that you stitch using the same software, and this software does not care about sensor technology.

Or do I miss something specific about film?

There are several key differences when doing film-based panoramas.

One is that you have an extra step of variability (the scanning). So for example, while it is easy to lock the camera settings between shots, it takes a bit more conscious effort to make sure that the *scanner* uses the *exact* same settings (including color and exposure) for the scans. The same goes for cropping as well, as the stitcher uses the full image frame to calculate FOV, distortion, etc, etc.

A second difference is that film grain is difficult to "blend"... so it is somewhat more likely that your film-based stitched panoramas will have artifacts (banding in particular). High-ISO digital shots have the same problems, but low-ISO digital shots tend to fare much better.



tobbsman wrote:
If I would do pano with film (and I was thinking a lot about it) I would
- get a Linhof Technorama

Absolutely! For film-based panoramas, a dedicated panoramic camera is hard to beat. Cool


PostPosted: Mon Aug 08, 2011 3:16 pm    Post subject: Reply with quote
Scheimpflug wrote:
peterqd wrote:
To me it looks as though there's some weird distortion going on in the unmerged pictures, before CS4 tried to merge them.
Make sure you don't confuse "distortion" with "perspective" or "projection". Wink

I thought I was being kind! To me it looks as though the two shots were taken in different positions. Smile


PostPosted: Mon Aug 08, 2011 3:21 pm    Post subject: Reply with quote
Scheimpflug wrote:

There are several key differences when doing film-based panoramas.

One is that you have an extra step of variability (the scanning). So for example, while it is easy to lock the camera settings between shots, it takes a bit more conscious effort to make sure that the *scanner* uses the *exact* same settings (including color and exposure) for the scans. The same goes for cropping as well, as the stitcher uses the full image frame to calculate FOV, distortion, etc, etc.

A second difference is that film grain is difficult to "blend"... so it is somewhat more likely that your film-based stitched panoramas will have artifacts (banding in particular). High-ISO digital shots have the same problems, but low-ISO digital shots tend to fare much better.

Thanks for this detailed answer. Ok, definitely higher complexity.

Edit: but as film is full-frame, stitching would be less required Very Happy Arrow


PostPosted: Mon Aug 08, 2011 4:13 pm    Post subject: Reply with quote
Scheimpflug wrote:


Excalibur wrote:
it seems the results are never going to be any good with just two images unless I have plenty of overlap either side of the subject and then crop.......


Not so! I've shot plenty of two-image panoramas. In general, 1/4 to 1/3 overlap will give the best results, but in a pinch, I've stitched some with as little as 5-6 pixels of overlap. Shocked


Thanks for sharing your knowledge, but I don't understand why you say "not so!".......on seeing my pano I've lost some of my picture at the ends after cropping, so surely I would have to go beyond the subject on the left for first shot and to the right of the subject on the 2nd to allow for cropping for the trapezoid shape? Also why is the finished stitch a trapezoid and not a rectangle?


PostPosted: Mon Aug 08, 2011 4:57 pm    Post subject: Reply with quote
Happy to help. I would re-stitch your source images for you to show some examples, but I'm at the wrong computer...

Personally, I find it easiest to understand when you think about the whole process at a high level. The panorama stitcher takes these "flat" images, then using clues such as the focal length (in the EXIF data for digital, or manually entered or guessed for scans), it calculates the FOV and tries to map these pixels into a 3D space. So for example, if you shoot a 360-degree panorama, it can automatically calculate the field-of-view to a very high accuracy, as it *knows* (via the matched feature points) that the images all fit into a strip that joins at both ends.

Once the stitcher knows the positions of the images in a 3D sense, then it can do another set of transformations to get them back to a "flat" image again. It is all heavy math, I won't even pretend to know all of those details. Very Happy But basically, there are a number of defined "projections", which change how this is done. Your stitched image appears to be in a cylindrical projection, which approximates a scanning camera. It is a common default, as it preserves a lot of your original in a rectangular crop... Whereas a projection which preserves straight lines would not.

In this case, the bulk of the trapezoid shape is a result of the horizon placement. Since the camera was pointing down, you have captured more under the horizon. Wink You should be able to artificially shift the horizon, and get a more rectangle result... But your buildings at the bottom might look funny. Wink


PostPosted: Mon Aug 08, 2011 5:58 pm    Post subject: Reply with quote
I rendered the scene fastly with my stiching engine ...
corrected also the horizontals and verticals in the stiching software ... which appeared a bit weird in those shots (I guess it was also a bit of a problem of capturing the frames)

what I saw is that the lens vignetts, see left up corner ... no good for stiching at all. better take a lens which has as less distortions/vignetting etc. as you can get.





The result is not really satisfying. Check that you also take same shutter for each frame, else you get those bad sky overlaps as in this shot ...

Cheers
Tobias


PostPosted: Mon Aug 08, 2011 6:29 pm    Post subject: Reply with quote
tobbsman wrote:
I rendered the scene fastly with my stiching engine ...
corrected also the horizontals and verticals in the stiching software ... which appeared a bit weird in those shots (I guess it was also a bit of a problem of capturing the frames)

what I saw is that the lens vignetts, see left up corner ... no good for stiching at all. better take a lens which has as less distortions/vignetting etc. as you can get.





The result is not really satisfying. Check that you also take same shutter for each frame, else you get those bad sky overlaps as in this shot ...

Cheers
Tobias


Oh well, it's thumbs down for a Hexanon 28mm f3.5 lens Crying or Very sad My next two shot pano will be of Windsor castle (next to Eton college) that you might have heard of (swarming with tourists last week) with a 24mm Ensinor lens...when I've used the rest of the film up. In fact it's only about 45min cycling distance from my house and might go back and try sigma 24mm superwide II and Canon FD 28mm lenses.


PostPosted: Mon Aug 08, 2011 7:06 pm    Post subject: Reply with quote
Quote:
My next two shot pano will be of Windsor castle (next to Eton college) that you might have heard


Smile Yes my parents took me there many many years ago ...
What I remember are the small ultra-clean gardens inside, ... the grass cut 5mm as on a golf court Wink I hope I remember the right place.


Quote:
with a 24mm Ensinor lens...when I've used the rest of the film up. In fact it's only about 45min cycling distance from my house and might go back and try sigma 24mm superwide II and Canon FD 28mm lenses.


concerning panorama-progress I can recommand you NOT to take to wide angles for the beginning. A 35mm is perfect to practise with on ff and gives natural results concerning pano-distortions.
If you have a zeiss Flektogon 35/2.4 in possession, it's the perfect lens to start with.
Looking forward to your windsor shots ...

Cheers
Tobias


PostPosted: Tue Aug 09, 2011 7:09 am    Post subject: Reply with quote
tobbsman wrote:

concerning panorama-progress I can recommand you NOT to take to wide angles for the beginning. A 35mm is perfect to practise with on ff and gives natural results concerning pano-distortions.
If you have a zeiss Flektogon 35/2.4 in possession, it's the perfect lens to start with.
Looking forward to your windsor shots ...

Cheers
Tobias


Thanks...I do have Canon FD 35mm f2.8 and Hexanon 40mm f1.8 and for plan B have plenty of excellent 50mm lenses.......but if none of my wide angle lenses are good enough for panos with buildings, I'll just have to use them for the countryside.


PostPosted: Tue Aug 09, 2011 8:51 am    Post subject: Reply with quote
You should definitely get great pano results with Canon FD 35mm 2.8.

Cheers
Tobias


PostPosted: Tue Aug 09, 2011 3:46 pm    Post subject: Reply with quote
Windsor castle using 24mm Ensinor lens and Superia 100asa film, just supermarket scan to about 3mp.

first shot


2nd shot


Photomerge


Nothing to do with panos but thought I'd tuck this shot in while I was near the castle (same Ensinor lens), thinking back I could have taken better/interesting shots with a zoom... oh well, maybe next time.


PostPosted: Tue Aug 09, 2011 6:29 pm    Post subject: Reply with quote
Your second attempt is hugely improved. My only comment would be, and I am OFTEN guilty of not doing this, making it four shots, two with more sky, to make it more of a square image. The clouds there look like they were pretty dynamic and could have added a lot to the photo. Another workaround for that would have been three shots with the camera rotate 90 degrees.


PostPosted: Tue Aug 09, 2011 7:18 pm    Post subject: Reply with quote
David wrote:
Your second attempt is hugely improved. My only comment would be, and I am OFTEN guilty of not doing this, making it four shots, two with more sky, to make it more of a square image. The clouds there look like they were pretty dynamic and could have added a lot to the photo. Another workaround for that would have been three shots with the camera rotate 90 degrees.


It's all exciting and when members like Tobbsman were taking so many shots for a pano, it put me off using film, but I am surprised what you can do with two shots when you want to "get it all in" but can't step back far enough. Anyway I'll try more shots per pano next time as it's a handy skill to know and use at times.
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