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Topic: view-pipeline
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Andreas Ruf

Posts: 11
Registered: 12/7/04
view-pipeline
Posted: Mar 6, 1997 6:58 AM
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I've some trouble with 3D-plots in matlab, in particular when Im given
the perspektive 4x4 transform P directly by view(P).
How does the viewing pipeline actually work. What I understood sofar,
that given a point A=(x,y,z) its homogenious coordinates
a(x,y,z,1) are multiplied by P, and then a orthographiq projection via

O = 1 0 0 0
0 1 0 0
0 0 0 1

is done to obtain homogeneous screen coordinates, that are finally (u,
v,w) displayed by u/w, v/w!
Summarizingly

u
v = O P a
w


However, as soon as I change to:

u
v = O P inv(H) H a
w


with P'= P inv(H) and a' = H a, and setting(view(P') and plotting a'
the projection should remain the same, is however distorted
significantly.

It seems to be that there is another transform or another V
in the pipeline!

u
v = o P V a
v

How is the projection actually realized ?

andreas





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