#CAMERA ACCURACY
12-Jan-94 23:46:23
Sb: #75846-#CAMERA ACCURACY
Fm: John K. Jordan 71174,711
To: Michael E Bartlett 71033,3070
>>3DS Camera/FOV…
You are correct in your observation of the focal length/FOV
un-relationship. We had some discussion on this earlier. A group I
do some work for was using some of my images to simulate a robotic
vision system. The optics guru ran into the same (small)
discrepency. However, with image processing calculations, "small" is
relative. <g>
The bottom line: don't use the Lens focal length value (50mm, etc) to
do scientific work. For historical reasons, the math behind the
focal length calculation was simplified to maintain consistency with
other Adesk software (as per Yost Group). (I guess at the time they
never thought a bunch of crazies would be trying to do science with
3DS!) The focal length value is fine for artistic merit and as a
good starting point for people familiar with 35mm cameras.
The FOV angle, however, proved to be mathematically right-on. You can calcuate
the appropriate focal length from the FOV.
JKJ (in focus this time)
PS: the robot vision system was an fantastic success – you CAN do great science
and engineering and (new military buzz-word:) Rapid Prototyping with 3DS.