circumference measurement for a shell

If you use a PS2 mouse as your sensor, there is an arduino library that will track the distance.

My system has to measure circumference of any circular/elliptical object which is larger in size.

I have been looking for the ideas to attain this.

Is it possible with ps2 mouse?

The ps2 mouse here will be in motion or stationary?

the entire area has to be covered as to measure circumference. either mouse has to roll over or shell has to rotate..

or else you have any other idea? kindly explain to me pls

im grateful

Let me add some details in my question to elaborate what I am asking for - The idea is to measure the vertical and horizontal distance traveled by the mouse without the screen size limitation. I have a wireless mouse which can move freely in any direction within 10-15 feet range. I want to use this advantage to measure any distance. I know I can map the maximum range of my mouse on my screen and can do that but I don't even want range of the mouse to be the constraint while measuring the distance. Do I need raw mouse data to do this?

Edit: Example - : What I am trying to do is measure the real world distance using mouse. Let say I have to measure the dimension of a table then I would just move my mouse on the table and it will register the dimension.

Few points to conclude the question

1. Can we use mouse to measure the distance?
2. Can we do it without modifying the mouse?
3. Since mouse cursor can't move beyond the screen it is difficult to measure the x,y coordinate, Isn't it?
4. Mapping the real world distance to screen is one solution but I don't want to that because it constraints it ability to measure the distance.
5. Can we move the mouse beyond the screen?
6. If we can, can we get the mouseX or mouseY location ?

A wheel coupled to an encoder. There are encoder sketches on line.

Yes a mouse can measure any size X and Y.

The encoder mentioned by Eliot can also do this.

How the output of encoder can be used to measure length?

can you provide me sample code ? point out example/links?

Thanks douglas for your guidance.

Wireless mouse can be interfaced with arduino for measuring circumference?

any examples/links/sample code

Try this :

http://blog.tkjelectronics.dk/2013/12/bluetooth-hid-devices-now-supported-by-the-usb-host-library/

i decide to go this encoders,as study says distance calculation of mouse varied with speed.

There are several encoders availabe in market.

should encoder suit my application for length measurement ie circumference.

Output of encoder can me converted to distance?

you have any idea?

Here is another possibility:

https://www.indiegogo.com/projects/01-world-s-first-dimensioning-instrument--2#/