Thread Subject:

epipolar line and coordinates in second image

Hi,

can any body suggest me some matlab code for the following problem:

I have matrix F (transformation matrix), and two image views.
(i)
I want to find out epipolar line on image 2 corresponding to a point in image 1.
(ii)
by using a point in image 1 and matrix F, how i can find coordinate of a point in image 2

thanks in advance for your help.
regards,
from
Image Vision

Hi,

You can use the Computer Vision System Toolbox to solve these problems
nicely.

1. You can use the "epipolarLine" function to compute the epipolar line. For
example, the epipolar line in image 2 corresponding to a point, pt1, in
image 1 is
line2 = epipolarLine(F, pt1)

2. I guess your goal is to find the a point in image 2, pt2, which
corresponds to another point, pt1, in image 1. We knew that pt2 will lie on
the eipolar line, line2, for sure. We could test every location on line2 to
find the best match for pt1. The matching score of a location and pt1 can be
computed by comparing some features extracted from their surrounding
regions. Because the epipolar line can have arbitrary orientation and the
two images may have different scales, reliable features are difficult to
find.

A better solution is to rectify the images firstly. Then the corresponding
points will have the same row position and the two images will have the same
vertical scale. You can use the "estimateUncalibratedRectification" function
to compute the rectification transformations. Please see the example of this
function for the use of it. Then you can use simple block matching along the
row direction to search the corresponding point. You can also use the
"disparity" function to compute the disparity, which returns the location of
all corresponding points in the image.

Thanks,

Huibao

"imagevision " wrote in message
news:julvf7$a5o$1@newscl01ah.mathworks.com...

Hi,

can any body suggest me some matlab code for the following problem:

I have matrix F (transformation matrix), and two image views.
(i)
I want to find out epipolar line on image 2 corresponding to a point in
image 1.
(ii)
by using a point in image 1 and matrix F, how i can find coordinate of a
point in image 2

thanks in advance for your help.
regards,
from
Image Vision

Thanks for the reply.
I dont have that tool box.
please guide / suggest some code example (s ).
regards,
from
Image Vision



"Huibao_Lin" <hlin@mathworks.com> wrote in message <jumbk1$sj4$1@newscl01ah.mathworks.com>...
> Hi,
>
> You can use the Computer Vision System Toolbox to solve these problems
> nicely.
>
> 1. You can use the "epipolarLine" function to compute the epipolar line. For
> example, the epipolar line in image 2 corresponding to a point, pt1, in
> image 1 is
> line2 = epipolarLine(F, pt1)
>
> 2. I guess your goal is to find the a point in image 2, pt2, which
> corresponds to another point, pt1, in image 1. We knew that pt2 will lie on
> the eipolar line, line2, for sure. We could test every location on line2 to
> find the best match for pt1. The matching score of a location and pt1 can be
> computed by comparing some features extracted from their surrounding
> regions. Because the epipolar line can have arbitrary orientation and the
> two images may have different scales, reliable features are difficult to
> find.
>
> A better solution is to rectify the images firstly. Then the corresponding
> points will have the same row position and the two images will have the same
> vertical scale. You can use the "estimateUncalibratedRectification" function
> to compute the rectification transformations. Please see the example of this
> function for the use of it. Then you can use simple block matching along the
> row direction to search the corresponding point. You can also use the
> "disparity" function to compute the disparity, which returns the location of
> all corresponding points in the image.
>
> Thanks,
>
> Huibao
>
> "imagevision " wrote in message
> news:julvf7$a5o$1@newscl01ah.mathworks.com...
>
> Hi,
>
> can any body suggest me some matlab code for the following problem:
>
> I have matrix F (transformation matrix), and two image views.
> (i)
> I want to find out epipolar line on image 2 corresponding to a point in
> image 1.
> (ii)
> by using a point in image 1 and matrix F, how i can find coordinate of a
> point in image 2
>
> thanks in advance for your help.
> regards,
> from
> Image Vision