Vision Sensor focal length

[mateo]

hi, where can i find the focal length value of a vision sensor in v-rep?
thanks!

[coppelia]

Hello Mateo,

V-REP uses the angle of view of a camera, instead of the focal length. You can calculate one from the other. In V-REP, take the largest from a view's width or height: that corresponds to the angle of view of the camera or vision sensor.

You can modify this in the camera's dialog (Perspective angle), or in the vision sensor's dialog (Perspective angle).

Cheers

[mateo]

thanks a lot for the exhaustive answer...nevertheless i have a doubt: is it the right formula (the one i should invert): \(\alpha=2 \arctan\left(\frac{d}{2 f}\right)\) ?
in that case i should know \(d\) ...but i don't.. right?
thanks again

[coppelia]

Hello Mateo,

The focal length makes sense only in situations where you have a real projection surface, like a camera film or camera sensor. If you have a real camera with focal length F, then check what the film size / sensor size is for the value of d. Then you can calculate the angle of view and use that in V-REP.

Cheers

[mateo]

now I understand,
so, if i want to use the usual formula to change reference space, from camera space to image space:

\(U_i=f \frac{X_c}{Z_c}\)

\(V_i=f \frac{Y_c}{Z_c}\)

which \(f\) should i use?
thanks
matteo

[kleinash]

Wish there was a way to upvote..

[coppelia]

Hello,

have also a look at this post.

Cheers