Changes in frequency-integrated intensity of various hydrogen and helium lines as a function of distance along the vertical direction through the field of view defined by the first thread (from bottom to top), for different numbers of randomly unaligned threads (using the p4 model). The intensity is given in erg s^-1 cm^-2 sr^-1 and the vertical position in the field of view is given in Mm. The horizontal axis represents the position vertically away from the solar surface with the zero point at the centre of the first thread.