One-dimensional time domain helicopter-borne electromagnetic responses are computed using G-S transform and Gauss numerical integral. The variation of electromagnetic responses due to bird height is analyzed, and then the variation of bird height is transformed to the variation of pseudo-layer thickness of zero conductivity to eliminate the error of the altimeter. Based on the pseudo-layer model, conductivity depth imaging is conducted using artificial neural network while the apparent height is introduced as the output of ANN. CDI obtained by artificial neural network is much closer to the true model than that by lookup table method, especially for resistive layers.