Lyman-alpha emitters and their intensity map are powerful probes of the large-scale structure at optical and near-infrared wavelength as HETDEX plans. Given typically very high optical depths, scatterings due to neutral hydrogen have a non-negligible impact on the observed distribution of Lyman-alpha photons. To study this in detail, we run a suit of radiative transfer (RT) simulations on Illustris and investigate two possible distortion effects on the galaxy clustering signal arising from RT in real space (Behrens, CB et al. arXiv:1710.06171) as well as in redshift space (CB, Saito et al. in prep.).