Originally from Moravia, Semerak worked as a scenic painter for theaters. Afflicted with schizophrenia, he was unable to continue working and received a disability pension.

His drawings, which fill the entire sheet of paper, are teeming with meticulous detail. Executed in diluted India ink and tempera paint, he built, drawing after drawing, a vast encyclopedia of an obsessive world, populated by airplanes, boats, trains, and visionary architecture from which faces sometimes emerge.

His works are nourished by historical, architectural, or mythical themes, symbols from different cultures and religions, and revolve around a central figure, likely a kind of self-portrait.