If your getting an fbx with an existing offset from an app like maya, then
shouldn't you need the offset in distance, not pixels?  Maya's filmback
offset is measured in inches.

-deke

On Mon, May 2, 2011 at 06:24, John RA Benson <[email protected]> wrote:

>  width = 1998
>
>   lens
>  offset
>  calculated offset from camera u
>
> (-u/2)*width
>
>  calculated u from offset
>
> -1*(2/width*offset
>
>  win_translate.u (from camera fbx file)  20 -24 -18.34 0.024
>  0.01835662  23.1 -24 -5.34 0.024
>  0.00534497  24 -38 -29.04 0.038
>  0.02906466  24 -24 -18.34 0.024
>  0.01835662  35 -30 -22.92 0.030
>  0.02294578
> Strange - something funny with our fbx conversions then? Or maybe the
> win_translate isn't the filmback offset?
> I would have thought the values for offset and calculated offset would be
> the same, and the actual win_translate.u and the calculated u would be the
> same.
> the actual offset for the first shot is -24 pixels and the win_translate.u
> = 0.18, yet the calculated u is 0.024.
>
> The 2 cameras with offsets of -24 both had a u of 0.018, but by using these
> calculations it should be 0.024. I'm not sure what's correct...
>
> jrab
>
>
> Deke Kincaid wrote:
>
> u would be:
> -1 * (2/width * offset)
>
> v would be:
> ((root.format.h/root.format.w)*2)/root.format.h * offset
>
>
> -deke
>
> On Thu, Apr 28, 2011 at 14:26, John RA Benson<[email protected]> 
> <[email protected]> wrote:
>
>
>  While we're on the subject of cameras and a little matrix math -
>
> does anyone have the math for converting pixel values of the offset of a 
> filmback into the window u value for the camera?
>
> Say I want to offset the image by 15 pixels, I'd need to adjust the window u 
> by ... ?
>
> thanks!
> JRAB_______________________________________________
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