blog added 10/01/2004

DeFish Settings for Sigma 8 mm Lens

Church Panorama
This panorama of a University College Chapel is a fairly difficult panorama to get to stitch correctly. It has beams in the ceiling and tiles on the floor. There has been no post processing to remove errors from this QTVR file, or artifact removal within Stitcher.

The QTVR movie of this chapel is found here.

There were a few comments on the QTVR Maillist forum that others were having difficulty with my settings. They seemed to have worked here.

However, I do not pretend to know why my settings work. I did try in the light of comments to change the settings to more understandable values but failed to get good stitches.
So here is my work flow and settings and original files so that you can experiment yourself with values.

Yes, I know the panorama is dark in this example, but I can easily (and have) recover the shadow detail in post-processing, but this isn't the task at hand here.

So my work flow is:

1) 7 photographs with Canon 10D plus Sigma 8mm, camera portrait position on the nodal point of the lens using a Kaidan spherical panorama-head. Exposure for each shot was same using full manual control. Looking at these photographs it is clear that one thing I didn't do was lock the white balance (here they are AWB), you should do this (of course shooting with Canon RAW allows you to set and lock the white-balance) and you should have it on manual focus too. The setting for the camera in this case were ISO 100, f6.7 at 1/30 sec.

2) Defish each using these settings.
 Setting
   (
   "Sigma8mm"
   FishRadius(1.456457)
   FishCenter(0 0)
   FishFOV(170)
   FishRotation(90)
   FishRadialPolynomial(1 0 0)
   Projection(perspective)
   FOV(90 120)
   Zoom(1)
   Options(rectangular noHemiCube dependentWidthHeight bicubic )
   )

3) In Stitcher overlay two images, set focal length to be 12.6mm, then run High Distortion calibration.

4) Add and stitch in rest of images.

5) Adjust all images at end - this gave end focal length of 12.673 (117.24) FOV and Distortion 0.006 to get things nicely aligned I have started to use the Stitching camera setting in Stitcher here I set this to x=0 y=-14 z=-1

6) Render spherical image as shown above as TIF file (5000x2500) - you can see the full resolution output here (900K .jpg)

7) Clickehere Cubic Converter is used to make QTVR movie.

Steps 2-7 take well under 10 mins on my computer to do.

Download original files here:
the 7 Canon .jpg files (12.1Mb)
the 7 Defished files (24.2Mb)

These are provided for you to experiment with and not to republish without permission.