Panoramas with different viewpoints

Discussion forum for techniques and issues relating to the creation of panoramic and/or "mosaic" images

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maxlyons
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Re: Camera traversing the subject - Traversoramas

Post by maxlyons » Thu Aug 13, 2009 11:19 pm

nwphoto wrote:I had been thinking about wide images of wide subjects for a long time, and had tried shooting Main Street from viewpoints on the other side. After some interesting failures I decided that what I needed was a LOT of very narrow images. But how to shoot those without wearing out the DSLR shutter, and myself?

Solution: video cameras happily shoot LOTS of images. So rotate an HD videocam to 'portrait' mode, mount it on my car window, and shoot while driving slowly along Main Street. Then write a program to extract, select every nth image and join them.
I have thought about this as well, but haven't ever found the time to try it. I would guess that it ought to work pretty well as long as the distance between the car and the subject doesn't vary. Do you have any examples that you can post? Have you tried doing this where everything was at the same distance from the camera (i.e. no foreground)?

Max

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Re: Camera traversing the subject - Traversoramas

Post by nwphoto » Thu Aug 13, 2009 11:27 pm

maxlyons wrote: I have thought about this as well, but haven't ever found the time to try it. I would guess that it ought to work pretty well as long as the distance between the car and the subject doesn't vary. Do you have any examples that you can post? Have you tried doing this where everything was at the same distance from the camera (i.e. no foreground)?

Max
I'll look out and post some examples tomorrow.

I've not had a subject like that yet, but Main Street between the side roads, with no parked cars, might come close. Early on Sunday morning might be OK.

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Re: Camera traversing the subject - Traversoramas

Post by maxlyons » Fri Aug 14, 2009 12:05 am

I'll look out and post some examples tomorrow.

I've not had a subject like that yet, but Main Street between the side roads, with no parked cars, might come close. Early on Sunday morning might be OK.
Yes...one would have to choose the subject carefully. Another idea would be to add some "intelligence" to the program that extracts regions from the video frames so that the excerpt widths are enlarged to encompass whatever foreground images might be present. Even this wouldn't be a general solution to the inevitable parallax problems (and would very tricky to do in an automated fashion), but should help produce better results.

Max

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two examples of Travo work-in-progress images

Post by nwphoto » Fri Aug 14, 2009 5:00 pm

(tho not much work or progress recently).
However, here is a link to some explanation and two sample images.

http://www4.telus.net/public/wexsessa/travo.html
John Hall

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Re: two examples of Travo work-in-progress images

Post by maxlyons » Fri Aug 14, 2009 10:48 pm

John,

The pages look interesting but it looks like at least two of the images are missing:

http://www4.telus.net/public/wexsessa/i ... 62x244.jpg
http://www4.telus.net/public/wexsessa/i ... avo11c.jpg

I think that this is an interesting project to pursue...for me, however, the stitching tools are sufficiently mature that they probably don't need reinventing. I think the real opportunity is in creating the software that extracts the appropriate slices from the video stills that allow for the best creation of a single composite image, with the minimum amount of visible parallax errors.

Max

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Re: two examples of Travo work-in-progress images

Post by nwphoto » Fri Aug 14, 2009 11:28 pm

maxlyons wrote:John,

The pages look interesting but it looks like at least two of the images are missing:

http://www4.telus.net/public/wexsessa/i ... 62x244.jpg
http://www4.telus.net/public/wexsessa/i ... avo11c.jpg


I think that this is an interesting project to pursue...for me, however, the stitching tools are sufficiently mature that they probably don't need reinventing. I think the real opportunity is in creating the software that extracts the appropriate slices from the video stills that allow for the best creation of a single composite image, with the minimum amount of visible parallax errors.

Max
Sorry about those missing files, Max, they are there now.

I agree re the stitching - that's why TravoMaker does not try to do real stitching, just abuts the images. There is an option to create separate files for each image slice, so that they can be properly stitched with a normal pano program after the selection step.
John Hall

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Post by sK8z » Mon Aug 17, 2009 3:25 pm

John, Max

i find it pretty awesome to see this discussion right now - i just finished a project for a friend of mine shooting the main shopping street in my city - about 1km, both sides.

My approach was "step, shoot, step, shoot" and it got old FAST lol

end result was that i couldn't for the life of me get any pano software to work - pta, ptgui, hugin - with any sense of reliability - so i used the "auto align" feature in cs4 with just the reposition checked, and manually lined all 300ish shots up.
from there i used the "auto blend layers" to blend small groups of layers at a time, then flatten and blend the blended stuff.

My final result turned out better than i expected, but you two are right the errors you get form far off tall buildings are hard to avoid. I ended up masking them off and recreating sky around them.

http://www.flickr.com/photos/grahamrose/3787140170/ for the photo page, and
http://farm4.static.flickr.com/3464/378 ... 6a_o_d.jpg to grab the original. you can see lots of little errors, but for the intended output (3" high) they won't show (and i'm still working on it ;P)
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Graham R

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Interesting, but too small to see well

Post by nwphoto » Mon Aug 17, 2009 7:23 pm

Hi Graham,

what I can see on the web page is interesting, but when I try to save it for a closer look, all I get is a single pixel.

But what you have is impressive, at least to those of us that know how difficult anything in this endeavour is.
John Hall

sK8z
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Post by sK8z » Tue Aug 18, 2009 4:52 pm

John, thanks for taking a peek

odd it didnt work

i have uploaded a 10kx600 version to my server - this link should work

http://www.homeshots.ca/sgr.jpg
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Graham R

nwphoto
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OK, I got a full image

Post by nwphoto » Tue Aug 18, 2009 11:13 pm

The 1-pixel thing was from the first posting I tried. When I used the the posting in 'Galleries' it was OK, so I have now seen a good copy.

Rather neat. Its a pity these need so much work and attention.
John Hall

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Post by Jim Z » Tue Sep 08, 2009 10:25 pm

The vid-cam software is a really neat idea!

The other thing to do, except that I can't afford to buy the camera, would be to drive along with a Seitz 'Round Shot' camera not spinning/turning but looking sideways out of the car. A digital version of a moving film slit camera. The longer exposures with the Seitz are ~several minutes.

The things that were close to the camera would be compressed horizontaly, and you'd have to do it on a blue sky day... but I think it would be perfect for that street scene, and no (maybe/prob) blending work!
Jim Z

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moving film & slit cameras

Post by nwphoto » Tue Sep 08, 2009 11:06 pm

Hi Jim,

I'm aware of that camera, but not familiar with it.
But I seem to remember that they need to have the subject image moving across the slit at the same rate as the film is moving, so that any image-part is static with respect to the area of the film that it falls upon. The school photo cameras of my youth achieved this by having gearing between the film, camera body & tripod mount.

So I suspect that if shooting from a moving vehicle, the correct speed will have to be determined by a series of tests, and maintained closely in a final shoot.

I started exploring the Travo project because I already have the expensive part: the videocam, and any speed discrepancies can (theoretically) be corrected post-shoot by video line & frame selection. However, that is proving very difficult and is deferred until this winter's indoors-project time.
John Hall

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Post by Jim Z » Sat Sep 12, 2009 1:29 am

(I have never seen one in person, but) I think that the Seitz is exactly a digital version of the school photo camera. (They also make a very expensive wide scaning back rectiliner camera, a digital 6x17, so to speak.)

The reason I mentioned it is that it could be used analogous to a moving-film-past-a-slit camera. These give very strange looking photos of the 'photo finishes' of horse races and Olympic sprints, before they were replaced by high speed video. And they were used for aircraft recon cameras. Oblique view photos with a slit camera are very interesting and attractive photos, to me. Very long landscapes that look very much like your street photo.

Digital or film, I think that you are right; the correct speed would have to be found and maintained. Even then, things in the foreground would be compressed in teh horizontal dirrection, and things in the distance would be stretched horizontally, if I've figured it out corrrectly... Only one range, camera/subject distance, would have the correct horizontal to vertical aspect ratio.

With out the redic expensive Seitz camera, could you capture only a single, center, line line from the vid cam, continously, and not have to do any blending? Record the image as sequencial single vertical lines, recorded at the frame rate?
Jim Z

nwphoto
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Seitz-like image from videocam

Post by nwphoto » Sat Sep 12, 2009 10:10 am

"With out the redic expensive Seitz camera, could you capture only a single, center, line line from the vid cam, continously, and not have to do any blending? Record the image as sequencial single vertical lines, recorded at the frame rate?"

Hi Jim,
If I understand you correctly - yes.

You could select one video line from each frame, or variations on a theme. Remember, the videocam is rotated to the 'portrait' orientation.

TravoMaker lets you select frames, and lines within frames:

* the starting frame,
* the ending frame,
* frame 'stride', i.e. every third, seventh or whatever frame)

and within the selected frames:
* 'strip' width, i.e. a group of 'n' lines centered on the middle line.

All the 'strips' are appended to create the wide image.
(with an option to separate the strips with a white line, so you can see the individual strip components of the whole)

I'm considering further work on it, to show the strips in relation to their neighbours, with the intent of selecting frames/strips manually for 'best fit'.

As TravoMaker is written in Python (a powerful but easy-to-learn language), even a non-programmer could probably soon learn enough to make changes. If you like, I could post some of it here, or will email the whole thing to you if you want to explore it.
John Hall

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Post by dsp » Sun Sep 20, 2009 5:53 am

I thought of this thread when I saw this fantastic centerfold (in National Geographic :) )


I think this is an incredible pano, and one of many beautiful shots in the article (and most NG articles!). Anyway, you can see the cool rig that they used to make the shot, and the trouble they went through. It makes taking a bizillion megapixel image with a fixed tripod seem easy - it may be "small" compared to some of the panos out there, but as they say, size isn't everything! Only after I read the caption, did the techno-junky in me came out, and I looked for some evidence of stitching errors. You can clearly find some, especially on adjacent trees but I don't think they diminish the accomplishment, or detract at all from the finished picture...
Kudos to the Nick Nichols and the rest of the NG team.

http://ngm.nationalgeographic.com/video ... ld&catID=1

cheers, Darcy

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