wwp@yahoogroups.com:
Re : Does the image width have to be divisible by 2 to join correctly?
Thomas Rauscher 2005-Sep-28 18:20:00
Hello,
on Wednesday, September 28, 2005, 19:23:39 you wrote:
MA> centreofengland wrote:
>> --- In #removed#, Thomas Rauscher <#removed#> wrote:
>>
>>>The problem is, that I currently use integer math for the cropping.
>>>The solution is to make the horizontal tiles a divisor of the image
>>>width.
>> Hi Thomas, So what you are saying is that lets say my jpg is 6550
>> pixels wide then I need to change the "Horizontal Tiles" value to 25?
>> If so then I guess its best if my jpgs are a nice round figure rather
>> than somthing like 6569 pixels wide.
Yes, correct. If you good with prime numbers you can choose any pixel
width, but I think its easier with "nice" numbers like 20, 25 or 30. I
will fix this in the next release of Pano2QTVR, so that the error is
spread to all tiles, so that it is not so much visible.
>> So the height of the jpg does not matter then?
No, the height doesn't matter, as long as you don't make horizontal
tiles. Than the same rule applies. (make 3 or 5 a divisor)
MA> Once upon a time ;) the rule for QTVRs was that each tile
MA> (!) measure (in pixels) had to be divisible by 4 - of
MA> course, that was in the days of cylindrical-only panoramas,
MA> but i think it hasn't changed since then.
MA> So, if you have 25 horizontal tiles, the value must be a
MA> multiple of (25*4) = 100 pixels since each tile must fit the
MA> rule. The vertical size must be a multiple of 4.
This only necessary for pre QT 3 clients.
From the "Inside Quicktime VR":
Important: The pixel dimensions of your image file should be evenly
divisible by 96 in the long dimension and evenly divisible by 4 in the
narrow dimension. This is important for tiling. This is only true if
you?re tiling into the standard 24 x 1 tiling. If you?re good with
prime numbers, you can use other tiling schemes, but the resultant
tile size should be divisible by 4 in each dimension (no longer a
requirement if all clients use QuickTime 3 or greater).
MA> Note: At least i think so - with the advent of Mac OS X,
MA> even Apple's free tools learned how to re-scale and optimize
MA> these values all by themselves, so there's no real feedback
MA> left (earlier tools would simply come up with all kinds of
MA> error messages instead, and even with a helpful one like
MA> "nearest possible size 6144x768" or something).
The Quicktime Tools do a rescale, but I don't wanted to do this,
because I don't want to loss quality by rescale by just 1 pixel.
MfG,
Thomas.