This paper is devoted to in-depth study of the crystallization process in the K2O-TiO2-SiO2 glass under thermal poling using a profiled anode and heating temperature below the glass transition temperature. The crystallization was investigated by Raman scattering and mechanical profilometry at the specified conditions. It was found that the glass remained transparent without crystallization signs on the electrode-glass contact surface (profile peaks at the electrode) whereas the glass surface became frosted over other areas where there was an air gap between the electrode and glass (it was shown to be caused by the formation of a nanocrystalline anatase layer). A transition zone a few tens of micrometers wide and a few micrometers high was formed between frosted and transparent glass areas, i. e. at the edges of the electrode-glass contact surface. The mechanism of formation of the crystalline phase and relief was discussed.