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Flat Horizons ???

PostPosted: Sat Jul 21, 2012 11:27 am
by Farrealm
Hi Everyone,

I posted a message about this a few months ago and still can't figure it out :(

Usually, Autopano works fine for me... no problems at all.

But... sometimes, typically when I have photos in a pretty flat landscape (and Australia sure is flat)... I end up with "wavy" or "S-shaped" horizons. No matter how much I try to correct (vertical lines, changing the centre-point, etc.) I can't get a straight horizon (see the example in this post).

I am just wondering what the problem is and how to fix it. I shot these images free-hand. Could it be the way I shot the images (I tend to not hold my camera perfectly straight). Is there a way to fix this in Autopano (I shot about 7 images over 160 degrees field of view)

Any suggestions, greatly appreciated!!!

Cheers!

PostPosted: Sat Jul 21, 2012 1:30 pm
by klausesser
Farrealm wrote:Any suggestions, greatly appreciated!!!

Hi!

My own experiences show that it helps to shoot three rows for dealing with a straight horizon. Even if you don´t need the upper or lower rows it allows to get the image straightened.
At least i never had any issues to get the horizon straight . . . :cool:

The other way is to care taking the shots levelled by using the AF-fields in the viewfinder as markers.


best, Klaus

PostPosted: Sat Jul 21, 2012 2:16 pm
by a a gruntpuddock
This is usually caused by not keeping the camera axis vertical and can happen even using a tripod.

I can normally get most of it out by adjusting the position of the centre point, but sometimes you have to move the centre from side to side as well as up and down.

If you select planar layout, you might be able to straighten it by putting a series of horizontal lines along the horizon, but this can create unacceptable distortions elsewhere.

PostPosted: Sun Jul 22, 2012 3:00 am
by Destiny
Hi.. You could, if you have it, just drop the image into PS and straighten it.. . Nice looking Billabong... ;)

Destiny...

PostPosted: Sun Jul 22, 2012 10:46 am
by Farrealm
Hi Everyone,

Thanks for replying!

I guess there is no excuse for poor photography! Most of the time I don't have this problem. But this is when I plan to go out and shoot some panoramas with my D90. I usually take time to level my tripod and take lots of images. Hadn't thought about shooting multiple rows, I will definitely try this out next time. Thanks Klausesser! Sometimes you can't help yourself though. I ended up at this place and thought I'd give it a go with my 'pocket' Canon. I was in a rush as well...

Moving around the centre-point usually helps me out, or straightening the horizon bit by bit (also using vertical line). This shot is impossible though. PS is a great tool as well, I usually use it to get rid of "that final bit of distortion".

Yeah I know... Australia isn't all flat... :-) I lived near the Snowy Mountains for quite some years. I must say though, there are some amazingly flat landscapes in Australia. Just see the example above ("Hell's Gate"). This is a photo of the Hay Plains, west of Hay in NSW. It is absolutely flat (except some emus sticking out here and there) and stretches for about 130km (almost the width of The Netherlands). I lived in The Netherlands for 27 years and thought these Hay Plains were rather impressive! (I mean... it doesn't even have the equivalent of the Utrechtse Heuvelrug!).... flat as a pancake...

Thanks everyone...

PostPosted: Mon Jul 23, 2012 10:55 am
by Farrealm
Thanks Artisan S. I appreciate your advice. Yes, I think it is something that is missing a bit (horizon tool). I think Autopano is a great bit of software. I spent quite some time trying all the different ones before I bought Autopano. At the time I thought it was the best and most user friendly stitching software (probably still is). There is the "Automatic Horizon" button but this doesn't seem to do much (in my experience). Possibly it is just difficult to develop for their IT guys? Anyway, I'll take more care with the control point. Cheers!

PostPosted: Tue Jul 24, 2012 4:23 pm
by [bo]
Just wanted to add a bit of advice to the topic, being a handheld panographer myself...

Most of my horizon problems are solved by re-creating the control points. Select each link, delete all CPs, create new CPs selecting segments of the photos near the horizon. Yes, that results in some problems in the foreground, but I rather retouch those than deal with a split seascape!

PostPosted: Thu Jul 26, 2012 8:24 am
by Farrealm
Thanks [bo] and Artisan. Deleting the CPs did the trick. I got rid of all of them and just created new ones around the horizon... I ended up with a horizon that was slightly curved but with a bit of final correction in PS it looked perfect! :D