Tilt-shift Miniature Effect
An extreme selective focus that makes a full-size scene appear to be a scale model.
In depth
The illusion works because the eye associates a very narrow band of sharpness with close-range macro viewing, so a scene with only a strip in focus is read as small. It is strongest from a high viewpoint, with saturated colour and bright light, and it is achieved either with a tilted lens or with a graduated blur in processing.
Examples in practice
A city street photographed from a tower with a tilted lens looks convincingly like a model railway layout.