Measure 3D position of target

Hi,

I am very new to Arduino programming and trying to calculate x,y coordinate of target object using arduino. I am not sure if I should be using Laser Range Finder or Gyroscope. I want to measure the position of target object relative to fixed point on my sledge probably base of an arm that is pointing to target object. Any help would be highly appreciated.

Update: Problem statement: To get co-ordinate of any point in 2D rectangle of length L and breadth B with vertices (0,0), (L,0), (L,B), (0,B) by rotating arm, pivoted at (L/2,0) .

I want to measure the position of target object relative to fixed point on my sledge probably base of an arm that is pointing to target object.

Perhaps if you drew and posted a diagram, the meaning of this sentence would be clear.

Thanks for your replies, I updated the question, hope its clear now.

To get co-ordinate of any point in 2D rectangle

Sorry, still not clear to me. How will the point be identified?