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Author Topic: Stack & Stich  (Read 2672 times)

michaelbiondo

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Stack & Stich
« on: February 11, 2009, 08:18:08 pm »

Hello, I am shooting architecture with a cambo ultima35 (with a 1ds mark III) using rear rise, fall & shifts to create a 9 image pano (3 across , 3 up/down)
then merging in CS3. So far so good. In high contrast situations I like to create stacks with bracketed frames and my problem is that I am getting images merged differently in CS3 thus when I create the stacks they are out of registration. Any Ideas??
Thanks.

bill t.

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Stack & Stich
« Reply #1 on: February 11, 2009, 11:14:26 pm »

Well I'm a stack-then-stitch kind of guy.  I use Photomatix batch processing to stack (with the auto-align feature turned on) then pass the stacked .tifs on to PTGui or PTAssembler for stitching.  Both of those can stack & stitch automatically if you wish, I guess I'm a little old fashioned in that regard.  BTW the very, very latest Photomatix update has some significant reliability improvements and the fusion stuff is hugely better than before.
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michaelbiondo

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Stack & Stich
« Reply #2 on: February 12, 2009, 09:24:59 am »

Thanks, I use photomatrix, some of the time. The bath processing feature is great. But I am looking for a way to stich the 9 frames first then create a stack and then use the bracketed exposures to paint in highlights & shadows using a layer mask. I will check out PTgui or PT assembler (will they run on a mac or do I need PTmac?) for the stacking phase of the workflow as CS3 is not getting me consistent enough results for fine registration of the layers

bill t.

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« Reply #3 on: February 12, 2009, 11:04:18 pm »

PTGui runs on Macs, have not personally used that version.  Well worth the investment.  There are others of course, but PTGui rarely raises my blood pressure.  The ability to easily toss out certain control points (like on moving vegetation) is great, and you can quickly edit control points in general.  Plus the real time preview lets you straighten out and rotate panos, and view the different available projections.  Runs very fast on PC's, I'm sure also on Macs.
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bill t.

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« Reply #4 on: February 13, 2009, 12:58:08 am »

To continue, if you shoot your bracketed images in registration as with a tripod then you can first stitch say your normally exposed bracket set, then save the control points with PTGui's File->Save which saves only the file names and stitching information.  The file will have a .pts extension.

Then load up say your highlight bracket set, and apply the same stitching parameters with File->Apply Template.  Select the .pts file you previously saved, PTGui will apply the same stitching information to the new bracket set, which will register with the previous one.

Of course you must have the same number of images, in registration.  CS4's File->Auto Align Layers function can be used to register slightly misaligned frames.  Load all your images in a layer stack, then one at a time select subgroups of your individual bracketed frames, and Auto Align.  Continue until your entire pano set is aligned (on a frame basis, not as a stitch).  Then if needed you can crop the entire stack in one operation to eliminate white space around various images.   Then go on to stitching.
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michaelbiondo

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« Reply #5 on: February 14, 2009, 08:02:40 am »

Thanks Bill, sounds like a great workflow. Yesterday, I just competed a project of 20 architectural shots where i changed my process slightly. Let me know how this looks to you. When stitching the images I chose the perspective option (instead of the auto option) in the layout section of the photomerge dialog box. Flattened the file, then combined all of the files (light, med, dark) into one file with three layers, two of which have layer masks and then proceeded to paint in my highlights & shadows. The registration of the all the images looked perfect to me.
No doubt that PT gui is a more robust, industrial grade stitching tool and I would love to check it out sometime but at the moment I have my hands full with wrapping my brain around the adobe products, and I have not even upgraded top CS4 yet!

bill t.

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« Reply #6 on: February 14, 2009, 09:03:08 pm »

Well there are plenty of ways to get things done, I'm always for the most direct path.

This got me thinking about CS4 stitching, so I ran few tests using a nightmare pano set.  28mm lens, camera tilted severely upward, len centering probably a few mm from optimum.  The worst thing you can do to panoramic stitching software.

The composite image is a CS4 cylindrical projection.  I have marked a few stitching errors on the cropped image.  Most of the image stitched pretty well.  As expected the indicated extreme area has some errors.  PTGui and other stitching programs would also give these errors on the first go-around, the main difference is that by carefully editing control points, I was able to get excellent final results with PTGui, but with CS4 there is really no recourse at this point.  (Does CS4 have some further adjustments I don't know about yet?).  But the bottom line is, the CS4 results are pretty good and on less tortured pano sets the results are essentially perfect (usually).

The curvy image is CS4's Spherical projection.  If there is a way in CS4 to correct it, I wasn't able to find it.  OTOH stitching is essentially perfect.  In PTGui it would take just a few seconds to fix this by dragging and rotating the image with the mouse.  The thing with this image is, spherical projection works better than cylindrical because the "hump" in the steel beams is less pronounced in a straightened-out spherical projection.

So it looks like CS4 is almost there for problem stitching, and possibly already there for most mainstream stitching.  Sure would be great to be able to do it all in one program!  But for now I'm holding on to PTGui, since it can fix all the "not-quites" still lurking in the CS4 stitching paradigm.
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michaelbiondo

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« Reply #7 on: February 15, 2009, 07:38:19 am »

interesting, As soon as I get a chance (or as soon as I get into a bind) I will check out PT mac as it really is fantastic having the control points, Of course by that time Adobe will probably find a way to build the control point option into CS5. Thanks for all of the advice and information as it was very helpful.
Michael
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