"Virtual" wide angle via stitching seems to have less distortion

I was playing with a 3x3 stitched image today and for fun did a
comparison with a standard single shot:

http://satin.sensation.net.au/rowan/widecompare.jpg

I found it interesting that although the stitched image has a
noticeably wider FOV, there's a lot less perspective distortion.

Unfortunately, it's a lot of work (and CPU time) to stitch 9 images
into one!

 

Since the software has to do a little stretching when it does the
stitching, I suggest that it is correcting some of the distortion, just as
you might have done to the single image.

 

rowan194 () a écrit
dans :

yes.
however, some software (even freeware) exit to correct te lens distortion.
like this one : http://www.photo-freeware.net/ptlens.php

 

I have done some good 7 shot wides and one 13 that was far more than one
lens could do.

 

More good stuff here, including a list of software
at the bottom of the page:

http://www.panotools.info/mediawiki/index.php?title=Lens_correction_model

BugBear

 

as you would expect shooting at a more standadard focal length for the
stiched shot.

to avoid prbelms with distortion when making long panoramas I generally
get best result around the 40mm equivilant. When I do this the stitches
are often seemless.

kosh

 

yes, most books on the matter suggest using normalish (50mm) focal
lengths. They also suggest turning the camera into 'portrait' mode to
get more vertical coverage and take more frames to cover the horizontal.

Nige

 

The reason you do that is you have the best stitch results if the middle of
your picture lines up with the horizon. And in the portrait orientation
you'll get more of the scene below the horizon.

Don <www.donwiss.com/pictures/> (e-mail link at page bottoms).

 

For those of us stuck in the Point&Shoot world, this is easy advice to
follow. My latest attempt at stitching, 3 frames with an FZ5 (widest
focal length 36mm):

http://ri22.uchicago.edu/~dmsilev/tibetan_concert.jpg

It stitched pretty well, except for a few inconsiderate people in the
foreground who moved around a bit between frames.

-dms

 

Stitching is great fun...but the reason it doesn't distort is 1) software
correction and 2) you are not using an extreme wide angle....so you start
with less distortion.

 

overage and take more frames to cover the horizontal.

asssuming you plan on ignoring the rule of 1/3's that is.

 

Interesting comments on photographic "rules" at
http://theonlinephotographer.blogspot.com/
including the following advice from contributor Ken Tanaka --

"... But don't, don't, do not start confining your creative ambitions with
"RULES."
They do not exist. Take the pictures that you like to take and let your own
frustration
be your guide to developing your own set of best practices. You may, indeed,
find that,
say, the "rule of thirds" works for your own eyes, or not! "

Also on the site are examples of great photos, together
with the cliche "rules" that they've broken.

 

Pretty spot on, but taken solely at face value, is misleading. Rules of
thumb do exist, and for tried and true reasons.

BTW, if you do not hit Return as your text approaches the edge of your
compose window, you won't get odd wrapping as above.

 

: BTW, if you do not hit Return as your text approaches the edge of your
: compose window, you won't get odd wrapping as above.

Not neccissarily. Not all usenet software works the same. For example my
software has a fixed line length and the original posting wraps correctly,
but when quoting in a reply it automatically adds a quote character (in
the above it is using ":") and then a return at the end of each line. But
when I reply to a quote of a quote this return may be beyond the end of my
particular line length and so there will be some wrapping and odd line
lengths. Each program will have a default line length (and some may be
user adjustable). But each program will likely be a different length. So
if one person quotes a line that is 75 characters long, and I reply with a
70 character line length, wrapping will occur. So until all of us are
using the exact same software and the exact same settings there will be
occasional mismatches.

Now some of us (like me) try to edit the mismatched line lengths in the
quoted material so it looks good, at least on a system using the same or
longer line length than me. Of course the best way to deal with this is
for all of us to just ignore the mismatches that do crop up from time to
time (and try to trim the amount of quoted material to the minimum
possible while making it clear what we are responding to).

JMHO

Randy

==========
Randy Berbaum
Champaign, IL

 

That can be fixed. If you stitch with PTGui you can output as TIFF files
and then mask out the people in the layers where you don't want them. I
have seen web pages explaining this, but I haven't bothered to do it
myself, yet.

Don <www.donwiss.com/pictures/> (e-mail link at page bottoms).

 

But in this case, the rule of thumb to level your panorama with the horizon
over-rules the rule of thirds rule of thumb.

The reason is simple. I have a true panoramic camera (swing lens) and if
the horizon isn't perfectly level it will come out curved. Sometimes this
can create an interesting, if gimmicky effect, but for a normal looking
photo it simply has to be level with the horizon.

The same thing happens with stitching software. If you tilt the camera up
or down, depending on which software you use, the result will either be a
curved horizon, strange distortions or it won't stitch properly. There are
ways of correcting for tilt with some software, but it's much simpler to use
a spirit level and keep the camera level when you take the photos in the
first place.

If you want a rule of thirds horizon after you've stitched your pano, it's a
simple matter to crop afterwards, much easier than taking the shots tilted
and making it harder to stitch.

In fact, it can often be difficult to visualise what a stitched pano will
eventually look like so it's worth covering a larger area than you think
you'll need in order to give yourself some leeway for a nice crop
afterwards. It's really annoying to cut the edges too fine then find that
you have bits missing in the final image, since some cropping is
unavoidable.

Paul

 

So use a different tool. Use a shift lens. On a 1.6x camera the +/- 11 mm of
shift provided by the Canon TSE lenses means that with the camera mounted
perfectly level, you can place the horizon anywhere from 3 mm above the
frame to 3 mm below the frame (landscape orientation of the camera) or
anywhere from 1 mm from the top of the frame to 1 mm from the bottom of the
frame with the camera mounted vertically.

So use a shift lens to get the composition you want...

But the above is _really really really_ good advice. I shot the following
one at 13mm (300D + 10-22mm) and should have used 12, or even 11 (the
building at the left got clipped). Oops.

http://www.pbase.com/davidjl/image/43504169/large

David J. Littleboy
Tokyo, Japan

 

Good advice for those who can justify it's cost. (or a proper view camera
even.)
For those who can't, more shots and more work in photoshop is required.

MrT.

 

I thought about doing that, but haven't had the time to play around with
it yet. I could make my life easier by just cropping out the whole
foreground, but I think the crowd of people adds enough to the picture
that I'd prefer to keep them in.

-dms

 

Yes, quite right but the original post by anyone should appear fine
unless their line wrap (soft) is unusually large or unusually small, no?