PanoTools mailing list archive

Sender:John Blommers
Date/Time:2001-May-03 17:38:56
Subject:Re: help with full frame fisheye


proj-imim: Re: help with full frame fisheye John Blommers 2001-May-03 17:38:56
To John Paraskevas,

May I recommend that you perform a lens calibration? This is done by 
mounting the camera over its nodal point on a level tripod and taking 
at least 3 precise overlapping photos of a scene. The image 
parameters for yaw, pitch, and roll are known accurately (pitch and 
roll are zero, and for 3 pictures yaw is 0, 120, and 140) and not 
optimized. Only a,b,c and v  are optimized - the resulting stitch 
should be excellent. The a,b,c,v values are used when stitching 
images taken with that lens from then on. My own findings are like 
your own. If you don't have a reasonably close estimate for v the 
optimiser may not be able to improve it.

Another way to estimage v is to photograph a know object from a known 
distance from a known angle (usually 90 degrees) and applying 
trigonometry. For example, suppose a 15-inch wide object w 
photographed from 36 inches d just fills the image. v = 2 * atan( 
(w/2)/d ) = 23.5 degrees

- John Blommers

>Hello everyone:
>  I'm fairly new to this list and I'm still trying to get comfortable 
>using  both PanoramaTools and PTgui.  My immediate concern is trying 
>to use images  taken with  a canon 15mm full frame fisheye on a 
>Canon EOS-1N body.
>My first question is wether it's possible to create cubic panoramas 
>using 7 or 8 shots around plus one up and one down with this lens.
>Right now,  I'm having a difficult time creating even a basic 
>cylindical panorama with this lens. What is the actual HFOV of this 
>lens? I've tried several numbers between 77 degrees and 136 degrees 
>with out success. My resulting jpeg images are just a mishmash of 
>non-connecting picture parts.
>Also,  is it necessary to do a panotools correction (radial shift) 
>in photoshop before importing the images to PTgui, and what would 
>the typical settings be for that type of correction?
>I'm hoping that someone out there who  has used this lens and camera 
>combination can provide some advise or share a script that would 
>give me a good starting point.   I would be extremely grateful for 
>any help at all.
>John Paraskevas

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