Hi,

I would like to know how to do the conversion to Matlab co-ord system given a set of co-ords which are in Cartesian co-ords system

Let say, I was given x,y coordinates of pixels in Cartesian system as  (-1,1), (1,1), (-1,-1), (1,-1) , assuming the 2x2 pixel is the Origin here.

Now I want to form the structuring element as given below

SE = 
1 0 1
0 0 0
1 0 1

Is there a function which I can use to do this.

Replies will be helpful

Thanks

On 10/30/2010 1:24 PM, madhu s wrote:
> Hi,
>
> I would like to know how to do the conversion to Matlab co-ord system given a set of co-ords which are in
 > Cartesian co-ords system
>
> Let say, I was given x,y coordinates of pixels in Cartesian system as  (-1,1), (1,1), (-1,-1), (1,-1) ,
 > assuming the 2x2 pixel is the Origin here.
>
> Now I want to form the structuring element as given below
>
> SE =
> 1 0 1
> 0 0 0
> 1 0 1
>
> Is there a function which I can use to do this.
>
> Replies will be helpful
>
> Thanks

I do not understand this "structuring element". What is it?

To rotate a vector, one multiplies it by a transformation matrix.

Is this what you want?

What is "Matlab co-ord system"? Sorry, I never heared of "Matlab 
coordinates systems"

--Nasser

Please refer this link

http://www.mathworks.com/help/toolbox/images/ref/strel.html

"Nasser M. Abbasi" <nma@12000.org> wrote in message <iai6jq$8ro$1@speranza.aioe.org>...
> On 10/30/2010 1:24 PM, madhu s wrote:
> > Hi,
> >
> > I would like to know how to do the conversion to Matlab co-ord system given a set of co-ords which are in
>  > Cartesian co-ords system
> >
> > Let say, I was given x,y coordinates of pixels in Cartesian system as  (-1,1), (1,1), (-1,-1), (1,-1) ,
>  > assuming the 2x2 pixel is the Origin here.
> >
> > Now I want to form the structuring element as given below
> >
> > SE =
> > 1 0 1
> > 0 0 0
> > 1 0 1
> >
> > Is there a function which I can use to do this.
> >
> > Replies will be helpful
> >
> > Thanks
> 
> I do not understand this "structuring element". What is it?
> 
> To rotate a vector, one multiplies it by a transformation matrix.
> 
> Is this what you want?
> 
> What is "Matlab co-ord system"? Sorry, I never heared of "Matlab 
> coordinates systems"
> 
> --Nasser

There is a strel() function.  But it doesn't make any sense to run a
filter with a 3 by 3 structuring element on an image that is only 3 by
3 pixels, so you'd better have more pixels in between -1 and 1 than
just 3.  And you'll need to know the calibration scaling factor and
the "real world" units that you want to use.  For example, -1 *what*?
Is that in meters, or microns, or light years?

But you need to think about coordinate systems (and not just because
your sentence didn't make sense (to me at least)).  MATLAB operates in
terms of matrices - that means pixels and elements.  That means you
have to keep track of, and create, spatial calibration factors on your
own.