>
> Why do you substract one here?
> >512/2-25-1 = 230

The pixel coordinates start at zero, so essentially the pixel runs from 230
to 231

>
>
> Thanks for your help!!
> Alexis
>
>
>
>
> >As far as I calculate, for your scene, <1,0,0> should be at <230,240>
> >
> >dx = 5.12
> >1/2dx = 2.56
> >@4x distance (100=4x25):
> >1/2dx=10.24
> >pix res = 2(10.24)/512 = 0.04 /pix
> >point <1,0,0> projected = 1/0.04 = 25 pix
> >512/2-25-1 = 230

actually all this was a bit unecessary.
By similar triangles, at 4x the focal distance (camera = 100mm, focal =
25mm), pixel resolution should be 4x larger (width, height 4x larger over
same number of pixels)
i.e., horizontal pix resolution at 100mm = 0.01 x 4 = 0.04 mm/pix
point <1,0,0> is transposed 1mm to the left, 1mm/0.04 mm/pix = 25pix
half image resolution = 512/2 = 256pix
subtract 25: 256-25=231pix
this is at the right side of the pixel, subtract one more to get left side
231-1 = 230pix
this is because the pixel coordinates run from 0 to 511

-tgq

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