Optical Wonderful
Geometric & Impossible Objects
Shapes and structures that look plausible at a glance but could never be built in three dimensions - impossible triangles, endless staircases, and the perspective tricks that make them convincing.
Café Wall Illusion
Perfectly straight mortar lines between offset black and white tiles look tilted. Change the shift, the mortar colour and the thickness to switch the illusion off.
Geometric
Escher's Waterfall (The Impossible Waterfall)
Escher's lithograph of water that flows downhill all the way round a loop and back to the top. Trace the route and find the joint that can't exist.
GeometricKanizsa Triangle
Three notched discs create a bright triangle with sharp edges that isn't drawn anywhere. Turn the discs and watch the triangle disappear.
Geometric
Penrose Stairs (The Impossible Staircase)
A staircase that climbs forever in a closed loop. Why each flight looks right, why the loop can't exist, and how the idea reached Escher.
Geometric
Penrose Triangle
Three beams that form an impossible closed triangle. Turn a real 3D model in the demo and find the one direction from which it becomes impossible.