PanoTools NG:
Re: Some more tests on Optimal Cubefaces.
Erik Krause 2008-Nov-01 14:52:31
Am Saturday, November 01, 2008 um 11:33 schrieb
philipp_koch_als_name_gibts_oft:
> Sorry, maybe this is a dumb question, but I
> simply could not get the same values when looking at the example on
> your website.
>
> To make it simple: Say, there is an equirectangular image with 1000 x
> 500 px.
>
> 1000 x 0.7 = 700
> 700 / pi = 222.8169203
>
> So, one could shrink the equirectangular image to 700 x 350 px in
> Photoshop and convert this image to six 222 x 222 px cube faces?
>
> Or am I getting something totally wrong here?
No. To simplify the calculation you can simply divide by 4.5 (app.
pi/0.7)
In any case: It might be best to not first reduce the equirect and
then create cubefaces but use a good anti-aliasing interpolator and
create the smaller cubefaces directly from the larger equirect. This
saves one interpolation step.
BTW.: While photoshop creats nice small JPEGs at good quality it
might be no good idea to use it for cubefaces stripes. In any stripe
there are at least two joints where the single cubefaces don't fit.
At these joints the jpeg compression creates artifacts that are later
visible in the resulting panorama. See
http://www.photopla.net/wwp0703/stripes.php for details.
If I remember correctly Pano2VR and Pano2QTVR create stripes using a
different compression scheme near the edges, which avoids these
artifacts.
best regards
--
Erik Krause
Offenburger Str. 33
79108 Freiburg
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