Curved horizons?

[Stephmw]

Hi Everyone,

I'm slowly going through my collection of cylindrical shot sequences, trying to get some half-decent animations out of them but I've hit a bit of a problem.

In the single-row pano below, the horizon line is towards the bottom of the frames and ends up having a massive curvature when seen as a cylindrical panorama (the shot is 270x80).

http://stephanemw.googlepages.com/sos_panorama.html

Are there any adjustments I can do to rectify this? Ideally I'd like the horizon straight, I don't mind distortions elsewhere.

Thanks!
Steph

[zleifr]

Maybe (hopefully) there is a better way of doing this, but padding the bottom of the image with black space so the horizon is at the midpoint, and then using borders.swf plugin to limit the downward tilt would work.....

[ericob]

The cylindrical projection [being used] assumes that the field of view above the horizon is equal to that below the horizon. In other words, the assumption is that the horizon is at the vertical middle of the image.

If the camera actually was level (not pointing upward), then indeed padding the image on the bottom until you get the horizon in the middle should produce a more normal looking image. You should then be able to use the limits plugin to prevent the user from being able to see the padding.

If the camera was pointing upward, padding the bottom isn't going to fix the perspective problem. However, in this image there conveniently aren't any buildings!

[Stephmw]

I've updated the link (http://stephanemw.googlepages.com/sos_panorama.html) with a padded image and it really does fix the horizon... what I haven't managed to do yet is find a good combination of either the Limits or Borders plugins (should I try them both simultaneously?) that constrains both the panorama & the camera to the image proper...

Any ideas?

[zleifr]

I know that you can do it IMPERFECTLY with the borders plugin, but you might end up effectively hiding some of the bottom of the picture on the sides. And also, the zoom will screw things up. If you set borders with normal zoom and then zoom out you will see the padded part.

I haven't ever messed with limits, but I would really try to make it work, or maybe a combination of both: Use limits and restrict downward tilt with borders, AND pad the image with the same color as the background, so if a bit pops out here or there, it is not obvious.....

[rullator]

Is there any way to set up FPP for usage with panoramas with off-centre horizons?

Sometimes I shot panoramas with -180,180 and -30,90, whereas the horizon is at 0 and the panorama is embedded using the cylConverter.