Mapping from hemisphere projection to latitude-longitude format


I used ImageMagick to convert from fisheye to rectangular projections.
I wasn't much concerned with the accuracy so I can't tell if it's
appropriate for you. You can find more here:

I also remember that I used one of the Radiance binaries to convert
from one projection to another. I can't remember which tool it was and
which conversions are possible. If you use a non-Radiance source image
you have to convert it to Radiance hdr format and add the view
specification to allow the conversion.



On Mon, Dec 7, 2009 at 12:41 PM, Claus B. Madsen <[email protected]> wrote:

Dear list members,

I use HDRShop to convert between mappings for environment maps, e.g., from
mirror ball to lat-long, etc.

I now have two other mappings that I wish to convert to lat-long (though I
realize that both mappings will only give me half a sphere, e.g., top half
of lat-long map).

1) An image taken with a Sigma 8mm 180 degree field-of-view fish eye lens to
take a high-res image of the sky (same hemispherical mapping as RADIANCE
renders into when using the -vth option for rview/rpict)

2) An image of a diffuse hemi-sphere (diameter of 0.3 meters, turned out on
a lathe) spray painted with a diffuse grey

I am convinced that both mappings are identical (i.e. identical to the
hemi-spherical projection model in RADIANCE). So far I have used the
'mirrorball closeup' format in HDRShop but found this to be the wrong
mapping yielding incorrect lat-long mappings. I have now understood the
entire geometrical issue and just need a piece of software to warp
hemisphere images to lat-longs ... perhaps a plugin for HDRShop?

A couple of years ago I raised this issue with the people who wrote HDRShop
but they claimed the Sigma lens should be treated as mirror ball closeup
when re-mapping in HDRShop. I am now convinced this is not true after having
tested it extensively.


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