[3] From 1942 to 1943, he studied at the Tallinn School of Fine and Applied Arts under Eerik Haamer and Johannes Greenberg.
[4] Ohakas started showing his works at exhibitions in 1946, and in 1959 he became a member of the Artists Union of the Estonian SSR.
[5] Ohakas participated in the renewal of Estonian art in the 1960s, and he was in close contact with Ülo Sooster and many artists from Tartu and Tallinn.
[5] Ohakas's work in the late 1950s was characterized by the "harsh style" (Estonian: karm stiil)[6] (e.g., Pirita, 1959).
Starting with the end of the 1960s, his geometrizing style often reached the point of being abstract or surreal (e.g., Natüürmort kannuga 'Still Life with a Pitcher', 1970; Linn 'City', 1973; Antiik 'Antiquity', 1974).