The pioneer in the technique of photographic collage was:

The correct answer is Raoul Hausmann. He was an Austrian artist and writer. And he was a forefather and dominant figure of the Dada movement in Berlin, who was known particularly for his ironic photomontages and his provocative writing on art. One of the important figures there also includes the experimental photographic collages, sound poetry and institutional reviews that has a profound influence on the European Avant-Garde in the aftereffects of World War I.