[Radiance-general] aspect ratio problem

[iebele]

Hi Carsten,

I have a real problem in understanding goniometry :(

Do you know how to solve your equotation when the horizontal view angle 
is known?
In other words, how do I get the value of vv when:

tan(vv) / tan ( 84 degrees ) = 576/1024

Thanks a lot!


>iebele wrote:
>  
>
>>Hi Lars,
>>
>>Thanks for your suggestion using image aspect ratios instead of pixel
>>aspect ratios.
>>
>>Anamorpic Pal is (as I understood) a 720x576 image stretched to 1024x576
>>by the displaying device.
>>This suggests a pixel of which width is 1.42 taller as its height.
>>
>>I tried your suggestion and rendered my image at 1024x576 square pixel
>>with a the vv value calcualted like this:
>>vv = vh / 1.42  (where 1.42 is 1024/720 )
>>
>>Rendering square pixels at 1024x576 works fine, at least the image fits
>>the videoframe.
>>But I really wonder if the way I calculated the vv value is correct.
>>
>>-Iebele
>>    
>>
>
>vv and vh are view angles. To fit them to a given image aspect ratio
>(height over width) make sure that the quotient of the tangents of the
>angles fit the image aspect, i.e. tan(vv)/tan(vh) = 576/1024 in your
>example.
>This gives you undistorted square pixels at the given resolution, I
>don't know however if this is what you need, 'cause I don't know how
>that stretching in anamorphic pal is done..
>
>-cb
>
>_______________________________________________
>Radiance-general mailing list
>Radiance-general at radiance-online.org
>http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
>  
>