Questions surrounding the degree of correspondence with reality, and the inherent limitation(s) in this respect of perspective views/images are much debated. In a sense, there is no single ‘optical reality’; because each perspective image involves unique visual, optical, geometrical, and (often) psychological factors such that particular solutions are required.
Linear Perspective
Perspective is complex as it reconciles 3-D physical space with 2-D visual/represented space. Achieving perfect equality is often difficult because there is no 1:1 correspondence among the dimensions involved. Patently, information may be lost in this process due to the inherent optical limitations of a single point of view, plus aspect of form changes and scale/size relations, resulting in reduced (or concealed/confused) visual information structures/details. Overcoming aspects of this geometric correspondence—or equivalence—problem is a key ‘goal’ of visual/optical/technical perspective.
The ‘correspondence or equivalence problem’ of linear perspective; refers to the fact that for a 2-D monocular image of a 3-D object projected onto an image plane (or 2-D surface), the projection does not contain adequate information to unambiguously identify the 3-D object form/position; whereby many differently shaped/located 3-D objects can potentially produce the very same image form.
To help solve this problem, we employ contextual factors, including often a metric grid or framework structure.
Solutions to Correspondence Problem
Certain kinds of perspective, for example, multi-view parallel perspective, can provide a partial solution to the correspondence problem (reconciling object/image equivalency). However, no monocular ‘convergent or parallel’ perspective can entirely sidestep the problem of scale—because any increase in projection scale/resolution reveals new structural details and thus apparent shape/ size changes in the perspective image.
Using monocular perspective to view/image an unspecified spatial reality with wholly uncertain geometry, one cannot unambiguously identify the source spatial object/scene geometry—without adequate knowledge of key perspective method facets (ref. known viewpoint, standard picture-plane geometry, recognised objects, established metric grid, manifest projection scale/resolution, etc).
In a way, a graphical perspective method such as linear perspective is a quantitative construction of space—whereby we employ pre-determined knowledge of spatial forms—or use of known, often designed, and regular scene geometry.
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