Mapping from hemisphere projection to latitude-longitude format

Claus.

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:

http://www.fmwconcepts.com/imagemagick/index.php

http://www.fmwconcepts.com/imagemagick/polar/index.php

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.

Regards,
Thomas

ยทยทยท

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.

Sincerely,
Claus

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