Re: Vertical misalignment

[P3D John W Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Fri, 9 May 1997 13:01:21 -0500
>From: "P3D Dr. George A. Themelis" <fj834@xxxxxxxxxxxxxxxxxxxxx>
>Subject: Re: Vertical misalignment

>>Somehow I managed to get the camera off-level, (tripod probably sank in 
>>the mud) and the only good picture shows a sloped horizon line. 
>>
>>I mounted this picture in an RBT, making no adjustment for the 
>>horizon. It looks fine (though it looks like someone was standing a 
>>little crooked).  I can tell that if I want to straighten this 
>>valuable shot, it will require rotation _and_ vertical adjustment. 
>>Needless to say, this slide has been on my To-Do list for awhile!

>I don't understand this rotation _and_ vertical adjustment.  The minute you
>rotate each chip individually to correct the phychological tilt that
>bothers you, you have introduced vertical misalignment which _cannot_ be
>corrected not matter what vertical adjustments you make.

However, working it in the other direction can sometimes be useful.
If there is vertical misalignment in the two views (for instance pictures
taken by hand with the camera at different elevation for the two shots),
then the stereo picture can sometimes be saved by rotating the two views -
the horizon looks tilted, but at least it forms a stereo pair. One of the
lunar surface stereo photos from the Apollo missions was mounted this way
in a Stereo World article some years back.

John R


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