1. A method for estimating a pose of a camera relative to a surface upon which a 3D object rests such that a volume can be estimated for that object in an image captured by that camera, the method comprising: determining a matrix K from parameters intrinsic to a camera used to capture at least one image of an object for volume estimation purposes; determining a camera translation vector T=[t X t Y t Z ] relative to a set of real-world reference coordinates in (X,Y,Z); determining a camera rotation matrix R from camera angles (φ,θ,ω) relative to the X, Y and Z axis, respectively, of said real-world reference coordinates, wherein said camera translation and said camera rotation are determined from depth values associated with pixels of a surface of said object, said depth values being measured by a depth sensor of said camera; and estimating a distance Z, of said camera, comprising: Z c [ i j 1 ] = KR [ X Y Z ] + KT T .