A street is a paved public thoroughfare in a built environment. It is a public parcel of land adjoining buildings in an urban context, on which people may freely assemble, interact, and move about. A street can be as simple as a level patch of dirt, but is more often paved with a hard, durable surface such as concrete, cobblestone or brick. Portions may also be smoothed with asphalt, embedded with rails, or otherwise prepared to accommodate non-pedestrian traffic.
Originally the word "street" simply meant a paved road (Latin: "via strata"). The word "street" is still sometimes used colloquially as a synonym for "road", for example in connection with the ancient Watling Street, but city residents and urban planners draw a crucial modern distinction: a road's main function is transportation, while streets facilitate public interaction. Examples of streets include pedestrian streets, alleys, and city-centre streets too crowded for road vehicles to pass. Conversely, highways and motorways are types of roads, but few would refer to them as streets.
In photography and cinematography, perspective distortion is a warping or transformation of an object and its surrounding area that differs significantly from what the object would look like with a normal focal length, due to the relative scale of nearby and distant features. Perspective distortion is determined by the relative distances at which the image is captured and viewed, and is due to the angle of view of the image (as captured) being either wider or narrower than the angle of view at which the image is viewed, hence the apparent relative distances differing from what is expected. Related to this concept is axial magnification -- the perceived depth of objects at a given magnification.
Perspective distortion takes two forms: extension distortion and compression distortion, also called wide-angle distortion and long-lens or telephoto distortion, when talking about images with the same field size. Extension or wide-angle distortion can be seen in images shot from close using a wide-angle lens (with an angle of view wider than a normal lens). Object close to the lens appears abnormally large relative to more distant objects, and distant objects appear abnormally small and hence more distant – distances are extended. Compression, long-lens, or telephoto distortion can be seen in images shot from a distant using a long focus lens or the more common telephoto sub-type (with an angle of view narrower than a normal lens). Distant objects look approximately the same size – closer objects are abnormally small, and more distant objects are abnormally large, and hence the viewer cannot discern relative distances between distant objects – distances are compressed.