Jean-Marc Vezien (jmv++at++grip.cis.upenn.edu)
Thu, 21 Mar 1996 17:51:52 EST
We are currently trying to input real calibration
parameters extracted from Sony CCD cameras into
a performer channel. Our parameters are the
standard parameters used in computer vision, i.e.
(u0, v0) : center of the image (intersection of
optical axis with image plane. Typically close
to (256,256) for a 512x512 image. Close but *not*
equal).
(sx, sy): scaling factors in both directions,
which is the number of imaging cells (image
pixels) per unit length.
We've tried to interpret these parameters in
term of the coordinates of a frustum and
by calling pfMakePerspChan. Unfortunately
we did not manage to obtain a matching between
real and synthetic images. We computed the formulas
for the (left,right,bottom,top) channel cordinates:
left = -u0 / sx (negative)
right = (512 - u0) / sx
bottom = -v0 / sy (negative)
up = (512 - v0) / sy
near = 0.001 (our unit was 1mm)
far = 10 (arbitrarily large number).
(note that our frustum is not symetric).
But apparently this is wrong: the object
is imaged shifted to the right in our
viewport, instead of being centered like
in the real image.
Does someone have a clue as to how to
compute the frustum, given our parameters
above ?
Thanks for any help,
Jm.
This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:52:34 PDT