wwp@yahoogroups.com:
Re: Image width / 96 and height
Markus Altendorff 2005-Sep-28 21:34:00
Dave 360texas.com wrote:
> So what I am gathering.. for a proper image width should
> be divided by 96, and be a 2:1 ratio.
>
> This set width numbers are divisable by 96 and /2 for
> 2:1. Of course we have to watch the final MOV file size
> too...
Note that this width rule only applies for Cylinders - if
you're using a 2:1 ratio, most likely it's not cylindrical,
but spherical! There's a very thorough explanation of the
rules and resolution calculations on the homepage of Ken
Turkowski:
http://www.worldserver.com/turk/quicktimevr/panores.html
Personally, i use a cube tile size of 640x640 (ugly) or
768x768 (less ugly) for the small panorama, and 1480x1480
for the fullscreen one. This equals a 4648x2324 spherical
panorama. Note that the cube face size is NOT simply the
spherical circumference divided by 4 - you've got to factor
the projection from spherical to cubical into it. Imagine
putting a ball in a box - the box' circumference will be
larger than the ball's.
My line of reasoning when i pick a cube face size is:
- the smaller the image is, the higher the JPG quality can
be set while maintaining a fixed file size
- vice versa, the larger the image is, the less JPG quality
can be used.
BUT:
- the larger the image is, the less noticable the JPG
compression "residue" will be (usual JPEG blocks are 8x8),
so i may get away with choosing less JPG quality
BUT (2):
- the larger the (uncompressed) image, the less smooth it
will pan in the browser (if playback buffer memory becomes
too tight)
Decisions, decisions...
-Markus