Entering the digitally-animated “Van Gogh: The Immersive Experience” is less like walking into a painting and more like stepping into an IMAX fever dream. In a room the size of a railroad barn, painterly trains come and go, filling the interior with images of soft gray smoke. Flowering almond trees shed their petals on the breeze, and reach to the sky, 40 feet above our heads.Painted sailboats float on a bubbling Rhone River, as yellow stars whirl in the blue night sky. Walls melt. Water pools on the ground. This section of the traveling exhibit is the climax of a multimedia experience, with its super-boosted subwoofer sound effects and eye-popping writhing visuals.