stitching pano shots

[OZAmateur]

i use cs4 to stitch pano shots and lately ive been having some real issues with the 'straightness' of the shots.
I have got some great shots taken of city skylines and use photomerge to slice them together and find that the horizon's are all sloping away (down to the left or right).
Ive done my best at ensuring that i take the photo's at the same level but still cant stop the processing coming back with a sloping horizon.

What am i doing wrong?

[William]

If you feel your right into Pano shots , Maybe think about a dedicated Pano head for the Tripod, This way you can rotate the lens around the Nodal Point , And after stitching you wont have to crop so much off the image , :) http://archive.bigben.id.au/tutorials/360/photo/nodal.html

[ameerat42]

OZAm, let's have a look at one like you mean. Am.

[OZAmateur]

64334

this was stitched using cs4 'auto' setting on photomerge.
image was re-sized to 1024 so i could attach it here. no other editing.
as you can see it dips to the right, each individual shot was taken at the same height by hand. rotating body left to right.

[ricktas]

My guess is you are not staying at the same level as you move 'by hand'. You can straighten this shot by using the ruler tool.

Select the Ruler tool (in CS4 this is under the eye dropper)
then draw a line along the horizon, that follows what 'should' be level
Go to Image : Image Rotation : Arbitrary.
Accept the angle that is pre-filed (this is from your ruler line)
Click Ok
Crop the result

[William]

You'll get a more acceptable image if you just rotate the camera on the same axis , Not the whole of your body , I would give a tripod a go also , I've had success doing Pano's with my 50 mm 1.8 doing 3 rows of 7 shots , And turned out great hand held , Never had those lines you've got though after the stitching , Even on CS3 Try doing the Pano with more space than needed , Just to give yourself more room for cropping maybe :) Oops ! Sorry Rick you snuck in before me , Good idea also

[OZAmateur]

thanks heaps for your help guys. I love pano shots and its something that requires a great deal of knowledge not just in how to take a photo but in how to process it.

William, the lines you see in my shot are the join marks and they are still there as the image was so heavily re-sized and i hadnt blended it.

[ameerat42]

OZAm. The above comments are fairly correct. This result looks like some I have got when I have "unconsciously" followed points of interest in the landscape, like the tall stack, and then tried to keep the
more interesting parts central. This image does not suffer much from "rotation" but rather from being skewed by the stitching program to follow a horizon line. When this happens I usually resort to Photoshop to fix it up. Have a look at the images I did in CS2 Photoshop. I used the blue guides to check what was straight or not. Click on the image for a larger view. Am.

Note that in the 1st image (a little bit of contrast applied) the stack is virtually vertical. The horizon dips away to the right.
http://ten6fg.blu.livefilestore.com/y1pQOPnWKPWz11eY7p_cOthdZRUr5rV_Z1aWRoczfxlTWcokQH5Lf_dMr9VnDJxrcScEqaeepW3veqFvQNTAa1PakJJRilaxdZy/bridge-1.jpg?psid=1 (http://cid-e15ffd049d805436.photos.live.com/self.aspx/AusPhotoPics/Tutorial/bridge-1.jpg)

In the 2nd picture I have "skewed" the image by lifting the RHS until the horizon is approximately level. Note how the bridge piers and the smokestack are still aligned with the vertical guide.
http://ten6fg.blu.livefilestore.com/y1p2hEJ_ikzS5Zcd07a7r7u7oK9-YRT4oPIiFSVHoahR1v3BfdDf1eVO2hXo0URRg-yOsUf4gOuLa6jkw7B2LTLG7TfaZW1-Tym/bridge-2.jpg?psid=1 (http://cid-e15ffd049d805436.photos.live.com/self.aspx/AusPhotoPics/Tutorial/bridge-1.jpg#resId/E15FFD049D805436!410)

In the 3rd pic I have "warped" the image to stretch the sky upwards a little on the RHS, then I have slightly cloned bits of sky and cropped the image a little.
http://ten6fg.blu.livefilestore.com/y1phvAsDMv5HTRGv3epohhfvfYkhEzLd9egz_JErLjf6K_7uNtqcNF9E1WZBZaOghZNr5EFvekAAHX8sliu8IcrFGl2kpEvotsz/bridge-3.jpg?psid=1 (http://cid-e15ffd049d805436.photos.live.com/self.aspx/AusPhotoPics/Tutorial/bridge-2.jpg#resId/E15FFD049D805436!411)

The 4th picture is the finished result. Note I did not try to fix this up too much. I am not sure what your whitish "cracks" in the image are from.
http://ten6fg.blu.livefilestore.com/y1prqUWuHN9Wzyo8QIQ3N9qjxgelJu9Zq8AA5-c_UM02pA-ni7EM-8Tye171_yzK19MsmrRz6NNZU_8LWzlxC0OR4kVjWs3RehA/bridge-4.jpg?psid=1 (http://cid-e15ffd049d805436.photos.live.com/self.aspx/AusPhotoPics/Tutorial/bridge-2.jpg#resId/E15FFD049D805436!407)

[OZAmateur]

ameerat...thanks for your detailed walk through of whats involved in fixing my pano.
it looks like if i take the information outlined here i can save myself a lot of time and return better photos.
as for the white cracks...they only showed up when i reduced the image size of the stitched pano. in the original full sized version they do not appear at all?!