A measurement probe, such as a touch trigger or analogue probe, is described that comprises a deflectable stylus portion and a wireless communications unit for transmitting stylus deflection data to a remote probe interface. The receiving end is adapted to receive a moving document. The linear texture is drawn on the model in a width of minimum dots regardless of the width occupying the coordinates after the perspective transformation of the model. Roots of a z-transform of the forward channel estimate and roots of a z-transform of the backward channel estimate are determined.