We propose a modified generalized Harvey–Shack model by adding the empirical correction factor related to the scattering angle on the basis of the original theory. The result shows that the modified model reduces the root mean square error (RMSE) from less than 2% to less than 1%, and the relative peak error from less than 50% to less than 20%, which significantly improves the accuracy of scattering prediction. The prediction of the Rayleigh–Rice model is not as good as the Harvey–Shack model. The RMSE of the Rayleigh–Rice model is within 2.5%, and the relative peak error is within 60%. © 2022 Optica Publishing Group