The photoelectric interpretoscope is a data processing complete set of equipment of photoelectric theodolite used in experimental shooting range. Its main purpose is to interpret the numerical value of the measuring angle of theodolite. And the medium is the measuring films photographed by theodolite. The original data is in the form of lattice. The traditional ways of data collection of photoelectric interpretoscope are firstly changing the lattice of films into pulse signals, and then rebuilding, enlarging and compressing them. Finally the lattice pulse signals are collected and distinguished by means of inquiring. But the rate of wrong code is always very high when the widths of pulse signals are not identical. A new way of data collection is presented in which the compressed lattice is collected within the time limitation permitted by computer with barycenter method. The method can also work properly when the widths of pulse signals are not identical. The distinguishability is increased and the rate of wrong code is reduced.