Please ignore the question I posted below. That was my misunderstanding. I
----- Original Message -----
From: "Kunihiko Igarashi" <kigarash@...>
Sent: Thursday, November 25, 2004 11:53 PM
Subject: Re: Re: [Playerstage-users] Stereo Head Disparity Image Question
> Another questions.
> I am trying to calculate distance using disparity information from the
> stereo head camera.
> From my understanding, disparity is the x coordinate difference between a
> certain object position on the left camera image and the same object
> position on the right camera image.
> Both image should be at distance f (focal length) from the camera, and
> disparity value should be less than the base distance of left and the
> right camera.
> I hope I am saying the right thing. Please correct me if I am wrong...
> Then, to recover disparity information, I only need to divide data from
> disparity image by fdiv, right??
> To find the disparity of the ith pixel of the image, we need to do
> disparity[i] = imagedata[i] / fdiv;
> I could get the ith pixel's imagedata using Andrew's method.
> I changed both imagedata and fdiv from network-byte-order to
> host-byte-order before calculation.
> Please correct me if I am doing something wrong at this point again.
> I became really confused at this point.
> First, what is the unit (e.g. m, cm, etc.) of the resulted disparity
> value. Is that in cm??
> Second, I believed that the focal length of the camera (which I could not
> find) does not change. So, changing the size of the camera image (e.g.
> from 320*240 to 60*45) does not change the disparity value that much.
> However, as the size of the image becomes larger, disparity value I get
> using the method above becomes larger. For example, disparity value I got
> at one pixel by above method is 8 when the image size is 60*45, but
> becomes 42 if the image size is 320*240. This value is also larger than
> the base distance of the camera. Why is this happening??
> Third, this is not really a StreoHead camera question, but is there an
> information about the focal length of the cameras?? Or is there any way
> to calculate it??
> Could anyone please answer my question??
> Thank you very much
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