Recommendations on getting a straight horizon?

Discussion forum for techniques and issues relating to the creation of panoramic and/or "mosaic" images

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Recommendations on getting a straight horizon?

Post by harryshin » Sun Aug 20, 2006 12:33 pm

1. I assume this has been asked numerous times before... but, can some folks out there give me some concrete tips on how to get a straight horizon?

2. Some basic data:
a. I use the manfrotto spherical head.
b. I shoot 28mm
c. Most scenes are not a problem, but in situations where one can
clearly see the horizon (ie the ocean against the sky) in panos
exceeding 180 degrees, I just have problems getting a pano where
the horizon is completely straight (usually one of the pano is not

3. I assume my problem occurs when capturing the images; I use a
bubble level etc... but the greater the pano capture (degrees), I
assume that a greater degree of errors occurs.

4. Any help appreciated.

Harry Shin

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Re: Recommendations on getting a straight horizon?

Post by maxlyons » Sun Aug 20, 2006 12:57 pm

harryshin wrote:can some folks out there give me some concrete tips on how to get a straight horizon?

If you are using PTAssembler, then there is no need to take the images so that the horizon is level. The software can deal with the images if they are rotated. (If you are using a simpler, auto-magic stitching program, then you may be out of luck. I don't know.)

Using PTAssembler, I'd suggest setting some horizontal control points along the horizon if you want to ensure that it is rendered as horizontal.

Assuming you are using cylindrical or mercator projection (rectilinear is a mathematical impossibility for images with FOV>180 degrees), then you can optimize all parameters for all images except yaw for one image. This will allow the optimizer to pick the pitch and roll for all images, and should allow the horizon to be rendered as straight.

Johns tutorial on the optimizer should be at the top of the reading list for figuring out how to take the "training wheels" off and use the optimizer to its full potential.


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Post by johnh » Sun Aug 20, 2006 2:22 pm

I think that where you have a broad expanse of clear horizon, it's best to assign a row of line control points (t3) along it, with just one pair of horizontal line points (t2). If the horizon passes through several images, a couple of t3 points on each image will be enough. optimized as Max suggests. It also works for equirectangular images too, BTW.


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