  In this work, we develop an updated model for pion-nucleus scattering in the
framework of the distorted wave impulse approximation in momentum space. We
construct the second-order pion-nucleus potential, which involves analysis of
pion-nucleus elastic scattering as a solution of the Lippmann-Schwinger
equation. The potential is based on the individual pion-nucleon scattering
amplitudes extracted from SAID, and its second-order correction is presented in
detail. We estimate optimal energy-independent parameters of the potential by a
multi-energy fit of the pion-${}^{12}$C total, reaction, and differential
elastic cross sections. We show the predictive power by applying it to pion
elastic scattering on ${}^{16}$O, ${}^{28}$Si, and ${}^{40}$Ca.
