Panoramics offset from the Horizon

my setup, Digital SLR, 12 mm lens (really 18mm on a Digital SLR)

15 degrees of down bubble (dip)

final image sizes are 1600 pixels high (I'm in vertical mode, camera rotated 90degrees using a pano setup from really right stuff)

Image sensor on Fuji S3 is 23mm high (in vertical mode)

Using the Perspective Photoshop Plug in from Pano Tools (http://www.all-in-one.ee/~dersch/)

step 1 - load images into photoshop, apply perspective filter set at 15degrees

step 2 - the fun

• 18mm lens at an angle of 15degrees means the centre line (horizon) is offset by 18mm*sin(15 degrees) = 4.6587 approx
• 23 mm image sensor producing 1600 pixels is 69.565 pixels per mm
• 4.6587 mm centre offset * 69.565 pixels per mm = 324 pixels so the centre of the image has to be moved down by 324 pixels.
• to move the centre line by 324 pixels, simply add 648 pixels to the top of the image using the photoshop canvas size tool. So a 1600 pixel image becomes a 2248 pixel high image.

step 3 assuming there is plenty of overlap in the images, trim the sides - making sure to make the images all the same size, or Panorama factory will complain. (This step has to be done because the perspective filter adds black side areas where the image has been shifted and there is no info, if you don't trim these, PanoFactory will try to blend black with whatever it is over leaving strange shadows).

Please note, when dipping the camera you must alter the position of the camera also, so an old nodal distance from the centre of the camera x, is now x * cos (15 degrees) for a 15 degree dip.

Note, if you have tilted the camera UP, then you need to add the space on the bottom off the image.

Why is all this neccesary ?

When PanoFactory warps the images based on the focal length of a lens, it has an assumption that the horizon is in the middle of the picture, so all the above stuff is simply a way of putting the horizon back in the place in the image where it should be (not originally the middle of the picture) so that warping can commence. You can then crop the space off afterwards.

Why do all this ?

well, I for one do not have a lens that will do a full 360 sphere, however I do have a lens I can do two passes with, one tilted down and one tilted up, then I can stitch the two together....