Zoom in to the center of the 2d rectangle area

How do I do the scaling of the area, here I draw a rectangle using the drag and drop method, I can do the 2d to 3d Conversion using

projector.unprojectVector(pos, camera);

      

        
        
        
      

    

but i can't zoom in to fix the area,

Do I need to apply local to world coordinates? if so how to do it? I only have THREE.PointCloud grid.

u can see the image, it will show what i am trying to do.

thanks in advance.