calibration of camera

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

calibration of camera

lombardijoseph
i used calibration.cpp from the openCV samples folder and a chess board
print out to calibrate my camera. The program for calibration run
successfully, but do i need to put any results for this calibration.cpp
into my program? or once i ran this program the camera is calibrated
forever? Do i need to run the calibration program each time i start my
application? what happened exactly during calibration?

thanks for your replies

Reply | Threaded
Open this post in threaded view
|

Re: calibration of camera

Marco Paladini
to calibrate means to measure camera parameters (focal lenght, zoom, central point..)
you might need those parameters in your programs or not.
http://en.wikipedia.org/wiki/Camera_matrix (follow from there,
interesting http://en.wikipedia.org/wiki/Category:Geometry_in_computer_vision)



----- Messaggio originale -----
Da: lombardijoseph <[hidden email]>
A: [hidden email]
Inviato: Mercoledì 7 gennaio 2009, 1:03:49
Oggetto: [OpenCV] calibration of camera

i used calibration.cpp from the openCV samples folder and a chess board
print out to calibrate my camera. The program for calibration run
successfully, but do i need to put any results for this calibration.cpp
into my program? or once i ran this program the camera is calibrated
forever? Do i need to run the calibration program each time i start my
application? what happened exactly during calibration?

thanks for your replies


------------------------------------

Change settings: http://www.yahoogroups.com/mygroups, select
   Get Emails (get all posts)
   Daily Digest (one summary email per day)
   Read on the web (read posts on the web only)Or Unsubscribe by mailing [hidden email]
Yahoo! Groups Links




     
Reply | Threaded
Open this post in threaded view
|

Re: calibration of camera

Golan Levin
In reply to this post by lombardijoseph
"Calibration" is not a procedure which is performed on your camera,
such that the actual device is somehow changed!

Instead, the calibration procedure returns a set of numbers which
characterize your particular optical arrangement. For example, the
calibration procedure determines the precise optical center of your
camera's CCD chip, and it calculates the precise field of view, and
the precise barrel distortion and torsional distortion caused by your
camera's optics.

Once your have calculated these numbers, you must use them in your
code. For example, you could use them to "un-warp" the camera image in
order to eliminate distortion from the lens. This is particularly
helpful for cameras with wide-angle lenses.

If your optics are extremely stable, then you should not need to
calibrate every time the program starts... but it can be helpful. Even
tiny changes to the focus/zoom of your lens will have significant
effects on the calibration numbers which are computed. Any camera
which has a possibility of moving (e.g. mounted on a robot) should be
calibrated periodically.

The Trucco & Verri book explains this well.
http://www.amazon.com/Introductory-Techniques-3-D-Computer-Vision/dp/0132611082

Best
Golan


--- In [hidden email], "lombardijoseph" <lombardijoseph@...>
wrote:

>
> i used calibration.cpp from the openCV samples folder and a chess board
> print out to calibrate my camera. The program for calibration run
> successfully, but do i need to put any results for this calibration.cpp
> into my program? or once i ran this program the camera is calibrated
> forever? Do i need to run the calibration program each time i start my
> application? what happened exactly during calibration?
>
> thanks for your replies
>