straighten panorama

my soft to make Panoramas (photostich) often ends up doing them on a curve. How can I straighten up the picture, ie decurve an image? thanx

"frederic pichon" wrote in message

my soft to make Panoramas (photostich) often ends up doing them on a curve. How can I straighten up the picture, ie decurve an image?

First you'll need to start with using a leveled tripod when shooting. Next you could use a different stitching utility, allowing to control yaw, pitch, and roll. The pitch and roll parameters can be used to distribute the tripod leveling errors evenly over the composite image.

Bart

Try Autostitch
http://www.cs.ubc.ca/~mbrown/autostitch/autostitch.html
"Bart van der Wolf" wrote in message

"frederic pichon" wrote in message

my soft to make Panoramas (photostich) often ends up doing them on a curve. How can I straighten up the picture, ie decurve an image?

First you'll need to start with using a leveled tripod when shooting. Next you could use a different stitching utility, allowing to control yaw, pitch, and roll. The pitch and roll parameters can be used to distribute the tripod leveling errors evenly over the composite image.
Bart

Bart van der Wolf wrote:

"frederic pichon" wrote in message

my soft to make Panoramas (photostich) often ends up doing them on a curve. How can I straighten up the picture, ie decurve an image?

First you'll need to start with using a leveled tripod when shooting. Next you could use a different stitching utility, allowing to control yaw, pitch, and roll. The pitch and roll parameters can be used to distribute the tripod leveling errors evenly over the composite image.
Bart

It is often more than that. A curved pano is due to the camera being pointed slightly up or down during taking. It is almost impossible to keep it level by hand. You are right that a leveled tripod will fix that.

I have a big, heavy pano head on a great tripod that will do that just fine. However, it's all rather big and heavy. So, I find that I rarely take it with me.

Luckily my Hugin frontend to Panotools will stitch it very nicely. However, it takes more that control points for the yaw, pitch, and roll to correct a curved horizon.

I have found that the best and easiest way to correct the curve of the horizon in Hugin is to have an object on each end of the pano that is vertical. Horizontal will work too. You then put in a "vertical line" set of control points. Do this for one frame on each end, giving you two vertical lines. Hugin/PT will straighten everything up just fine.

Of course, you don't always have anything straight in a pano. Landscapes are particularly bad for having nothing to line up to. I have tried to skew bits of the picture at a time in Photoshop, but it's a pain. It hasn't been very satisfactory either.

I usually stitch the pano and leave the curve in. Then Enblend. Then I open the pano in Hugin as one image. I then apply an artificial horizon using the same control point method as above. The difference is to make one horizontal line from the center to the right side and another from the center to the left side. You are likely to have to do it over several times until you get it looking right.

None of these techniques work very well for 360 degree panos. I have found that handheld 360 panos are almost impossible to get straight and not wavy. The pano head on a tripod will be what you want for 360.

Clyde

"frederic pichon" wrote in message

my soft to make Panoramas (photostich) often ends up doing them on a curve.
How can I straighten up the picture, ie decurve an image?

Someone else can point you to software tips, but permit me to point out the common errors made in panoramic. Solve the 'at the camera' issues first, and the software will be happy to do proper stitching.

A tripod is necessary. Use a leveling head such as the Manfrotto 3416. It will maintain level through 360 degrees with minimal hassle. Make certain your frames are of equal degrees, and make enough frames so that horizontal distortion is minimized. See the Manfrotto 300n for a very nice unit that goes on top of the 3416. Turn off autofocus. On many auto-everything cameras the focus will hunt between shorts. Turn off autoexposure! Expose for the brightest part of the scene, or within a reasonable lattitude. Finally, it is best to rotate the camera at the nodal point of the lens. I gave up on the manufactured units that accomplish the later because they are too flimsy or too expensive, and made my own. ...oh, and when you get everything set up right, a cloud will pass over the sun in the middle of your sequence and you will have to start all over. :)

well all this is good and fine for professional work, but I dont really feel like carrying a 4kg tripod on a 7 hrs hike to the top of the mountain, to take one souvenir picture...

Thanks for Autostitch, which works much better indeed, although it is slow and seems to drastically reduce the definition of the original pics. I was more inquiring for a way to decurve an image, something like a negative spherisation, which would enable to define a base curve, and transform it into a straight line, like an anamorphose.

PS doesnt do that??

"Clyde" a

"frederic pichon" wrote in message

I was more inquiring for a way to decurve an image, something like a negative spherisation, which would enable to define a base curve, and transform it into a straight line, like an anamorphose.

PS doesnt do that??

Filter - Distort - Spherize?

In article <431a2a8b$0$21299$>,
says...

Thanks for Autostitch, which works much better indeed, although it is slow and seems to drastically reduce the definition of the original pics. I was more inquiring for a way to decurve an image, something like a negative spherisation, which would enable to define a base curve, and transform it into a straight line, like an anamorphose.

I suggest you try panorama factory. It's shareware and you can evaluate it before you decide to buy.
It figures out everything for itself (although you can override and fine tune). It corrects for camera tilt, vignetting, barrel distortion and will produce cylindrical or spherical projections.
Most of the 360 interactives on my web site were stitched with this. If you are using a digital camera it even has some special features for that as well.

--
Robert D Feinman
Landscapes, Cityscapes and Panoramic Photographs
http://robertdfeinman.com
mail:

Lorem Ipsum wrote:

"frederic pichon" wrote in message

I was more inquiring for a way to decurve an image, something like a negative spherisation, which would enable to define a base curve, and transform it into a straight line, like an anamorphose.

PS doesnt do that??

Filter - Distort - Spherize?

That way is a huge pain. Besides, I've never been successful with it.

Clyde

"Clyde" wrote in message

Lorem Ipsum wrote:

Filter - Distort - Spherize?

That way is a huge pain. Besides, I've never been successful with it.

Sorry. I am not sympathetic. If people want true panoramas, then they have to make it in the camera first, or lower their expectations. The later seems to be the way most people go, so have at it.

"frederic pichon" wrote in message

well all this is good and fine for professional work, but I dont really feel
like carrying a 4kg tripod on a 7 hrs hike to the top of the mountain, to
take one souvenir picture...

Since you get the best results if you avoid the issues from the start, and at the same time want to travel light, try a spirit level in the camera's hotshoe when handholding the camera. You may also want to use a plumb-line type of string hanging from the lens (approx. entry pupil / nodal point) so you can keep constant height and rotation point. As a weight on the string you can use anything, like a carabiner.

Bart

"frederic pichon" wrote in message

my soft to make Panoramas (photostich) often ends up doing them on a curve.
How can I straighten up the picture, ie decurve an image? thanx

CS2 has the new mesh warp feature. Just the tool for what you want to do...

Are U using a digital camera to do the panorama's?? If so - read on...

I have just gone thru this process extensively - and I found something interesting.... The software used afterwards and whatever arrangement I had with the tripod (eg using a spirit level to get absolute level panning..) - none of that had any impact - I always got curved images. SO I took a look at the EXIF information in the file headers from the digital camera and noticed that the images I had been taking at the wide angle setting of the camera - had effective focal lengths of 8mm!!!! Even though on the camera I had selected wide angle and this was 35mm - the hi resolution CCD in my camera - 12,000 effective pixels - meant this was reduced from 35 to 8mm
So I did the frames again - this time selecting a much lower resolution AND zoomed in the camera lens. This of course meant I got a lot more frames to stitch together - but at least I could easily do this now manually. The results using stitching software were even better (PTGui for example)..

Hope this helps

"MetaMorph" wrote in message

Are U using a digital camera to do the panorama's?? If so - read on...
I have just gone thru this process extensively - and I found something interesting.... The software used afterwards and whatever arrangement I had with the tripod (eg using a spirit level to get absolute level panning..) - none of that had any impact - I always got curved images. SO I took a look at the EXIF information in the file headers from the digital camera and noticed that the images I had been taking at the wide angle setting of the camera - had effective focal lengths of 8mm!!!!

Distortion. Yep, you did the right thing to zoom out and make more pictures.

Lorem Ipsum wrote:

"Clyde" wrote in message

Lorem Ipsum wrote:

Filter - Distort - Spherize?

That way is a huge pain. Besides, I've never been successful with it.

Sorry. I am not sympathetic. If people want true panoramas, then they have to make it in the camera first, or lower their expectations. The later seems to be the way most people go, so have at it.

Well, I did explain how to straighten curved horizon panos earlier in this thread. I do it all the time with Hugin/PanoTools. Well, if it's less than 360 degrees.

Clyde

You mean ZOOM IN - zoom out gives a wider field and the problem I referred to!!

:-(

MetaMorph wrote:

You mean ZOOM IN - zoom out gives a wider field and the problem I referred to!!

:-(

Technically using a longer focal length won't solve the problem of curved horizons. It will make it less likely that you aim up or down. So, the curve is likely to be less pronounced. But curved horizons will still be there.

The only to not have curved horizons is to keep the camera level.

Clyde

On Tue, 06 Sep 2005 09:09:51 -0500, Clyde wrote:

MetaMorph wrote:

You mean ZOOM IN - zoom out gives a wider field and the problem I referred to!!

:-(

Technically using a longer focal length won't solve the problem of curved horizons. It will make it less likely that you aim up or down. So, the curve is likely to be less pronounced. But curved horizons will still be there.

The only to not have curved horizons is to keep the camera level.

....or flatten the Earth ;-)

--

Hecate - The Real One

Fashion: Buying things you don't need, with money
you don't have, to impress people you don't like...

Try this: take a long piece of light rope or heavy twine and tie a loop in the middle big enough to fit the lens through it. Tie the free ends together such that it supports the camera at eye level when you step on it with both feet (feet fairly wide apart).The rope defines a triangle with the base between your feet and the loop at the apex, with the camera lens in the loop. This arrangement is light and prevents side-to-side movement, though it does not prevent you from rocking forward and back. You pull up slightly with the camera to hold the rope taut. Use a mark in the viewfinder to hold the horizon level and the same distance from the top of all pictures. Try to pivot the camera around the loop as you take your pictures.

Tom Nelson
Tom Nelson Photography

In article <431b7f83$0$11073$>, Bart van der
Wolf wrote:

"frederic pichon" wrote in message

well all this is good and fine for professional work, but I dont really feel
like carrying a 4kg tripod on a 7 hrs hike to the top of the mountain, to
take one souvenir picture...

Since you get the best results if you avoid the issues from the start, and at the same time want to travel light, try a spirit level in the camera's hotshoe when handholding the camera. You may also want to use a plumb-line type of string hanging from the lens (approx. entry pupil / nodal point) so you can keep constant height and rotation point. As a weight on the string you can use anything, like a carabiner.
Bart

In article <4318bcd9$0$21294$>, frederic
pichon wrote:

my soft to make Panoramas (photostich) often ends up doing them on a curve. How can I straighten up the picture, ie decurve an image? thanx

"Tom Nelson" wrote in message

Try this: take a long piece of light rope or heavy twine and tie a loop in the middle big enough to fit the lens through it. Tie the free ends together such that it supports the camera at eye level when you step on it with both feet (feet fairly wide apart).The rope defines a triangle with the base between your feet and the loop at the apex, with the camera lens in the loop.

That reads nicely, but does not work as you imagine it does.

It's worked well for me on some pretty long exposures. Here's an example from the Museum of Natural History in London:
http://www.tnphoto.com/Whales1-w.jpg

Tom Nelson
Tom Nelson Photography

In article , Lorem Ipsum
wrote:

"Tom Nelson" wrote in message

Try this: take a long piece of light rope or heavy twine and tie a loop in the middle big enough to fit the lens through it. Tie the free ends together such that it supports the camera at eye level when you step on it with both feet (feet fairly wide apart).The rope defines a triangle with the base between your feet and the loop at the apex, with the camera lens in the loop.

That reads nicely, but does not work as you imagine it does.

"Tom Nelson" wrote in message

It's worked well for me on some pretty long exposures. Here's an example from the Museum of Natural History in London:
http://www.tnphoto.com/Whales1-w.jpg

I like the picture, Tom. Don't you agree that you could have avoided distortion by using a leveling head on a tripod and more pictures?

In article , Lorem Ipsum
wrote:

"Tom Nelson" wrote in message

It's worked well for me on some pretty long exposures. Here's an example from the Museum of Natural History in London:
http://www.tnphoto.com/Whales1-w.jpg

I like the picture, Tom. Don't you agree that you could have avoided distortion by using a leveling head on a tripod and more pictures?

Of course, but I didn't want to take a tripod and a pano head on a vacation trip to London from the USofA. The OP was looking for a solution for hand-held panos on backpacking trips.

Frederick Pinchon wrote:

well all this is good and fine for professional work, but I dont really feel
like carrying a 4kg tripod on a 7 hrs hike to the top of the mountain, to
take one souvenir picture...

Tom Nelson
Tom Nelson Photography