Path: news.mathworks.com!not-for-mail
From: "Steven Lord" <slord@mathworks.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Image comparison
Date: Tue, 27 Jan 2009 09:56:11 -0500
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"Niall 84" <niall_heavey@yahoo.com> wrote in message 
news:d8b82541-f147-4e5e-8529-11658b87e993@q30g2000prq.googlegroups.com...
> Ok,
>
> Apologies for the lack of clarity.
>
> Basically I am trying to develop a new algorithm that can be used for
> the RoboCup soccer competition. The basics of it is that there will be
> a database of possible images that the robot could see, and I want to
> match what the robot actually sees with its match in the database.
> (The database images will have information attached to it that will
> tell the Robot where it is located on the pitch)
>
> However, to take absolutely every possibility would mean millions of
> images, but I'm sure it is possible for images that are very similar,
> but may have been taken at a slightly different angle, or taken from
> very close to, but not exactly the same location, to be matched. But I
> don't know how I might go about doing this.
>
> Hope that makes more sense.

It sounds like a combination of image registration and optimization -- find 
the stored image that minimizes the "amount of transformation" necessary to 
make it agree with what the robot sees.

Two of the problems I can see:

1) defining how to quantify the "amount of transformation" (if the image 
needs to be rotated 5 degrees counterclockwise to match a stored view, is 
that a greater amount of transformation or a lesser amount of transformation 
than a translation of 5 pixels?  Which one is "closer"?)

2) dealing with "stuff" (other robots and the ball, most likely) that are in 
the picture that the robot sees right now, but are not in the stored 
database.  The "stuff" could block the robot's line of sight, concealing the 
features that the robot would need to match what it sees with a stored 
image.

 I'm sure there are others.

I'm not sure CSSM is the right newsgroup to be able to help you with either 
of those problems I described above.  You may have better luck asking in an 
image processing newsgroup, like sci.image.processing, to determine if 
there's a standard algorithm or approach you should use to handle either of 
these problems.  Then, if you need help implementing that algorithm in 
MATLAB, ask those questions here in CSSM.

-- 
Steve Lord
slord@mathworks.com