First off, let's be clear about one thing - The Secret Of The Unicorn is made by a person who first discovered Tintin as an adult. To be precise, it is made by someone who discovered Tintin after he directed Raiders Of The Lost Ark. When a French review said Raiders was a nice homage to Herge, Spielberg got curious.
No wonder, then, that in the 2-dimensional, static panels of ligne claire created by Herge, Spielberg saw characters in popping 3D - textured, shaded and in blockbuster-style action. He saw cliffhanging set-pieces and edge-of-the-seat adventure.