MultiCamSelfCal with only 2 cameras

[brian]

Hi,

is it possible to use MultiCamSelfCal for a two camera setup?

If not, can you suggest any other calibration toolset, which uses a similar approach?


Thanks in advance,

Brian

[João Carneiro]

Hi Brian,

This method is for more than two (as stated in the website – min 3 cams). You might want to consider Yves-Bouguet  toolbox using the chessboard:

http://www.vision.caltech.edu/bouguetj/calib_doc/index.html

Chrs,

 

Joao

[brian]

Hi Joan,

thanks for that hint. Unfortunately my system allows me to track only a very limited amount of markers, so the chessboard approach is not feasible.

Do you know any other techniques which are based on moving some markers (maybe with a known distance) by hand?

I've already spent some time, but could not find one.


Thanks,

Brian

[Zsolt Ero]

Hi,

I'm just normally a reader of this group, but I had a similar problem
some time ago when I wanted to calibrate a wiimote what can only track
4 dots. My solution was to have a laser-cutted 50x50 cm black acrylic
board with holes in it in a grid. Then you just either manually put a
led in the wholes or develop an Arduino controller for it to make it
automatic. I wanted to make it automatic and I finally I didn't have
time to do it, but I think my solution would have worked well. The
important thing is that for calibration you only need points, and you
can measure them one by one at a time!

Regards,
Zsolt

[Joao Carneiro]

Hi Brian,

>Do you know any other techniques which are based on moving some markers
>(maybe with a known distance) by hand?

If you have your 3d points coordinates and corresponding 2d image coordinates why not directly estimate your projection matrix?
Chrs,

Joao

[brian]

Hi Joao,

I meant that the relative distance between the markers is known, not absolute coordinates in 3d space.

At the back of my mind, I think I've already seen an approach using 4 markers arranged like an coordinate system with a distance of 20 cm to each other.

But I can't remember the system setup. Maybe it is just impossible.


Regards,

Brian

[Joao Carneiro]

Hi Brian,

With 4 points you cannot but with 6 or more you can.
What I was suggesting is that you just establish one of your 6 points as the origin and calculate the 3D coordinates of the other 5 or more points from that one. Use the corresponding image points to estimate the projection matrix according to the known relationship xi = PXi.
Please refer to "multiview geometry in computer vision" from hartley and zisserman.
Chrs

Joao