Help Needed - Pano Stitching

[AndrewKulin]

I have attached a zoomed in portion of a 10 shot-stitched pano that I am pulling together to give as a framed gift for my parents at an anniversary party in 3 weeks time.  I have noticed (at the last moment of course) on getting the picture printed out that I can see some curvy artifacts in the sky, particularly bad in this portion of the photo.  In order to get this thing reprinted and into the shop for framing and all, I basically have 5-6 days to make the corrections and get the print in to the framing place.

The attachment is a zoomed in portion of the overall shot, and made overly dark to easily illustrate the artifacts I am talking of.  I had posted the whole image in User Critiques under the heading Foothills Panorama if anyone wants to see the whole thing with "correct" levels.

The photos were made with 10 vertically aligned shots, using a 40D + 17-55/2.8 (180 sec, f6.3, ISO 400), on a tripod with cable release and pano head.  Processed using PTGUI.

Any/All suggestions welcome.

Thanks

[attachment=13717:36x12_Fo..._problem.jpg]

[Ben Rubinstein]

I have attached a zoomed in portion of a 10 shot-stitched pano that I am pulling together to give as a framed gift for my parents at an anniversary party in 3 weeks time.  I have noticed (at the last moment of course) on getting the picture printed out that I can see some curvy artifacts in the sky, particularly bad in this portion of the photo.  In order to get this thing reprinted and into the shop for framing and all, I basically have 5-6 days to make the corrections and get the print in to the framing place.

The attachment is a zoomed in portion of the overall shot, and made overly dark to easily illustrate the artifacts I am talking of.  I had posted the whole image in User Critiques under the heading Foothills Panorama if anyone wants to see the whole thing with "correct" levels.

The photos were made with 10 vertically aligned shots, using a 40D + 17-55/2.8 (180 sec, f6.3, ISO 400), on a tripod with cable release and pano head.  Processed using PTGUI.

Any/All suggestions welcome.

Thanks

[attachment=13717:36x12_Fo..._problem.jpg]

Firstly are you using or processing to 8 bit? That will do it in my experience when the program tries to normalize the levels between the shots.

If you provide me the files that you sent to the stitching program (tiffs I assume) then I'll run it through Autopano (I have a lot of experience with it) and send you the finished product. See if it fixes the problem.

[BernardLanguillier]

This is the result of using a lens at an aperture where light fall off is too important. I would stop down to at least f8 with even the best lens for this type of pano.

I have had an identical case 2 days ago, Autopano giga couldn't do anything, but PTgui Pro's vignetting correction did a perfect job.

Cheers,
Bernard

[Jonathan Wienke]

I'd redo the original frames and correct the vignetting in the RAW converter, output as 16-bit, and then re-stitch. If that doesn't work, then output as a Photoshop file with each section of the pano in a separate layer. Then you can airbrush the layer masks to blend manually, using a large-diameter brush with hardness set to 0.

[button]

Make sure your PTGui is the latest version.  There is an exposure correction function for adjacent frames under the "HDR" tab (if memory serves) that may help with your problem.

John

[bill t.]

In addition to 16 bit, if you are processing the originals in raw format bring the contrast and saturation as close as possible to what you want before going on to stitching or other post processing.  Usually you will suffer the least quality loss from radical contrast increases at the raw conversion step.  And to be perfectly honest, sometimes it is best to substitute a Photoshop gradation for smooth skies that are that noisy.

One technique to fix the stitched image is to create an empty layer on top of it, then select that layer.  Select the rubber stamp tool with Opacity set to about 30, with maximum feathering.  Take a sample of a relatively smooth area on either side of one of the lines, then move the stamp left or right (but not vertically) over a line and stamp over the line which after 2 or 3 clicks will sort of disappear.  Takes practice.  Main point is, have the new empty layer selected, so you don't trash you original.  The corrections will wind up and the empty layer where they can be erased (or blurred) etc without messing up the original.  You need to have "Sample: Current and Below" selected for this to work.

[bill t.]

Should also mention that old versions of Smartblend and other blenders can generate artifacts like that.  If you are using CS4 and PTGui, you can output your PTGui files as individual layers, then let CS4 blend them for you.  CS4 blending is arguably the best blender today, though others may disagree.  I have found it can do wonders on problem skies.  I have also heard that the current version of Smartblend and the PTGui blender in the latest release are excellent.

You should also consider noise reducing the original panels before stitching, noise makes blending more difficult, although CS4 blends noisy skies pretty well.

[Thomas Krüger]

If you have trouble to correct the vignetting in your RAW converter (output 16bit tiff) have a look at PTLens to correct the images before stitching.
http://epaperpress.com/ptlens/

[bill t.]

I'm just a sucker for an image like this.  Here's a quick PS fix.  The top layer is a gradation sampled from the existing sky, with 75% transparency to re-introduce a little bit of mottle, and some added noise to keep it in line with the original shot.  The matte around the Moon is too sharp, if should be softened a bit.  I reduced noise on the original with ordinary PS Filters->Noise->Reduce Noise.

The middle layer is a half-hearted attempt to rubber stamp over the blending lines, as described in my previous post.  It's not very important, the gradation is what counts here.

[AndrewKulin]

Thanks folks for all the suggestions.  Lots of ideas for me to mull over the rest of the weekend.

Answers to some questions or comments above:

Firstly are you using or processing to 8 bit? That will do it in my experience when the program tries to normalize the levels between the shots.

If you provide me the files that you sent to the stitching program (tiffs I assume) then I'll run it through Autopano (I have a lot of experience with it) and send you the finished product. See if it fixes the problem.

- Everything is done 16 bit, until the last step which is to convert to a jpeg for printing at 8 bit.

This is the result of using a lens at an aperture where light fall off is too important. I would stop down to at least f8 with even the best lens for this type of pano.

- I had planned in the future to shoot panos and landscapes at around f8, mainly for improved depth of field.  In past I have been shooting more wide open to let me use faster shutter speeds and/or lower ISO.  Did not know about this.

Make sure your PTGui is the latest version. There is an exposure correction function for adjacent frames under the "HDR" tab (if memory serves) that may help with your problem.

- When I did this I was at 8.14 - I see an 8.15 version is now available.

In addition to 16 bit, if you are processing the originals in raw format bring the contrast and saturation as close as possible to what you want before going on to stitching or other post processing. Usually you will suffer the least quality loss from radical contrast increases at the raw conversion step. And to be perfectly honest, sometimes it is best to substitute a Photoshop gradation for smooth skies that are that noisy.

- I made adjustments in ACR before stitching.  Where I may have gone wrong, if I understand your point correctly, is in using ACR on the resulting TIFF panorama file to make some additional adjustments, primarily in HSL, curves, and some tweaks to the sharpening.

Should also mention that old versions of Smartblend and other blenders can generate artifacts like that. If you are using CS4 and PTGui, you can output your PTGui files as individual layers, then let CS4 blend them for you. CS4 blending is arguably the best blender today, though others may disagree. I have found it can do wonders on problem skies. I have also heard that the current version of Smartblend and the PTGui blender in the latest release are excellent.

You should also consider noise reducing the original panels before stitching, noise makes blending more difficult, although CS4 blends noisy skies pretty well.

- I am running CS3 so I do not know if your blending suggestion with CS4 applies to my situation (I usually upgrade paid software such as Photoshop on an alternating version cycle meaning I am awaiting the arrival CS5)

So thanks again for all the suggestions.  It appears that I will either start this over again from scratch, or try Bill T's suggestions if time becomes a real constraining factor (his sounds like the quicker route at the moment).  I have to spend the rest of the long weekend (in Canada) painting the room in which I have my PC from a deep Hunter Green (yuck) to a neutral white (so 4 coats of primer/paint) plus, my PC hard-drive is jammed and so I am installing a larger drive (easy) and have to also attempt to add hard-drive space to my operating system's drive partition (dangerous, subject to total disaster, back-ups to be done of course)

[Panopeeper]

The "artifacts" we see here have nothing to do with lens and vignetting. They are the traces of stamping. Andrew has apparently tried to repair the image with the stamp tool. This is not impossible, but one has to be very cautious with it; it should be the last resort. If stamping has to be on the sky (i.e. there is no better way to do solve the problem), then stamping should occur with a soft brush, opacity much under 100%; I could not give a figure, I use sometimes 30%, sometimes 80%.

Even more important: before using the stamp tool, the sky should be separated and undusted. Stamping the dusty (i.e. slightly noisy) sky is a firm recipe for desaster. This layer must be kept in order to prevent it from being sharpened.

Btw, the long, straight road from the left edge shows some tiny alignment errors; one of them (not far from the group of dark trees) deserves correction.

Another issue: blending. I found Emblend better than Smartblend; but anyway, whenever there is a problem with the result of one of them, the other should be tried.

[AndrewKulin]

The "artifacts" we see here have nothing to do with lens and vignetting. They are the traces of stamping. Andrew has apparently tried to repair the image with the stamp tool. This is not impossible, but one has to be very cautious with it; it should be the last resort. If stamping has to be on the sky (i.e. there is no better way to do solve the problem), then stamping should occur with a soft brush, opacity much under 100%; I could not give a figure, I use sometimes 30%, sometimes 80%.

Even more important: before using the stamp tool, the sky should be separated and undusted. Stamping the dusty (i.e. slightly noisy) sky is a firm recipe for desaster. This layer must be kept in order to prevent it from being sharpened.

Btw, the long, straight road from the left edge shows some tiny alignment errors; one of them (not far from the group of dark trees) deserves correction.

Another issue: blending. I found Emblend better than Smartblend; but anyway, whenever there is a problem with the result of one of them, the other should be tried.

I can say with certainty I did not use any stamping tool on the sky, and if stamping was used, maybe ACR or PTGUI or Photoshop did so on my behalf.  

I will take a look at the road to the left and do what needs to be done.

Thanks

Andrew

[Panopeeper]

I can say with certainty I did not use any stamping tool on the sky, and if stamping was used, maybe ACR or PTGUI or Photoshop did so on my behalf

I don't think either of those software made any stamping on your behalf. However, the banding, judges from the relative size, occurs within a frame as well (at some places the distance between the bands is only one-two moonwidth). Furthermore, the centers of those curves appear to be at or above the height of moon; this does not bode with either vignetting or vignetting correction. Or is it made of two rows of five shots each? But then the frames are even wider, encompassing more space, i.e. several bands are in one frame.

[bill t.]

CS3 also has File->Auto Blend Layers, although I only started using that with CS4.  Probably best to merge together any layers with their own adjustment layers, then select all the layers, then Auto Blend.  This leaves you with the original layers, but with masks that define intricate, wiggly blending paths between adjacent panels.  The nice thing about PS blending is that it is at the single pixel level, there is never any problem with artifacts from overlapping areas with superimposed pixels from two or more images, and it never alters the contrast or fiddles with color balance AFAIK.  Flatten the image before going on.  In the rare occasion when PS blending doesn't work out, try one of the other blenders.  Which one were you using BTW?

That stuff absolutely does look like rubber stamping with no feathering, the first I ran into it from an old version of some blender I was quite puzzled about when I had done all that rotten stamping!

The technique I described is possibly not the best, but it works and is very fast, you can fix a pretty big pano in just a few minutes once you get the hang of it.

[alainbriot]

Andrew,

Try Photomerge in CS4.  It works great.  File>Automate>Photomerge.  I've never had banding or artifacts with it and I stitch huge files.

[Jeremy Payne]

Try Photomerge in CS4.  It works great.  File>Automate>Photomerge.  I've never had banding or artifacts with it and I stitch huge files.

Slightly off-topic question ...

Is it true that CS4/Photomerge isn't as good as AutoPano/Smartblend when it comes to handling moving objects/people/etc within the frame?

[bill t.]

Smartblend is exceptionally smart about solving problems when there are objects in one adjacent panels but not the other or where and object has moved between shooting adjacent panels.  It's usually the easiest solution when you have pano sets of that kind.  However, the last-resort way to eliminate those kinds of problems is have your originals panels in layers with masks that you can edit to remove spurious objects that even Smartblend can't deal with.  Photogmerge gives you just such a layer stack by default, so you have the option of hand tweaking intractable problems.  But most of the time all you will need to do is flatten the layers that Photomerge creates.

For maybe 3/4 of typical panos Photomerge is a completely satisfactory solution.  If you get puzzling results, go back and try "Cylindrical" instead of "Auto" in the dialogue box.  Auto (which is the default) will not give good results when the camera was tilted very much up or down from the horizon.

[AndrewKulin]

I ended up combining a number of suggestions and redoing this from scratch.  In the end I used Photomerge in CS3 to do the stitching and it did a fine job (I did notice one small error that I let slide).  

I did notice artifacts after cropping the panorama to 34 x 8 (inches) so I went back, flattened the image a redid the crop and the artifacts (like small (1 pixel wide) vertical tears) disappeared.  They were found along the joins and I guess they are due to imperfect resizing of all the separate layers during cropping (I set crop tool to make the crop 34 x .

Those other curvy artifacts from my original attempt I cannot answer how they got there, probably from working and reworking the panorama over a number of sessions.

Here's the panorama I am now happy with.  Thanks for all the useful suggestions.

Andrew

[attachment=13919:36x12_Fo..._flatten.jpg]

[bill t.]

Worth the effort!  A beautiful, subtle image that well utilizes the panoramic format.

[AndrewKulin]

Worth the effort!  A beautiful, subtle image that well utilizes the panoramic format.

Thank you very much.


Andrew