Five of Dicke’s brothers studied engineering in Delft but Otto wanted to be an illustrator and artist. With no formal training he started working as an illustrator at an advertising agency but soon established himself as an independent commercial artist. Alongside this he worked one day a week teaching model drawing at the Rotterdam Academy of Art (Rotterdams Academie voor Beeldende Kunsten).
He painted many commissioned portraits but the landscape was his passion. His landscape drawings were often made as a protest against the mindless way in which the landscape was being treated. He liked Drenthe and visited often.