Editing Depth perception (section)

=== Perspective ===
{{main|Perspective (visual)}}
The property of parallel lines converging in the distance, at infinity, allows us to reconstruct the relative distance of two parts of an object, or of landscape features. An example would be standing on a straight road, looking down the road, and noticing the road narrows as it goes off in the distance. [[Visual perception]] of perspective in real space, for instance in rooms, in settlements and in nature, is a result of several optical impressions and the interpretation by the [[visual system]]. The [[Visual angle|angle of vision]] is important for the [[apparent size]]. A nearby object is imaged on a larger area on the [[retina]], the same object or an object of the same size further away on a smaller area.<ref>''[https://www.univie.ac.at/mikroskopie/1_grundlagen/optik/Grundlagen%20der%20Optik.pdf Grundlagen der Optik].'' page 24.</ref> The perception of perspective is possible when looking with one eye only, but [[stereoscopic vision]] enhances the impression of the spatial. Regardless of whether the light rays entering the eye come from a three-dimensional space or from a two-dimensional image, they hit the inside of the eye on the retina as a surface. What a person sees, is based on the reconstruction by their visual system, in which one and the same image on the retina can be interpreted both two-dimensionally and three-dimensionally. If a three-dimensional interpretation has been recognised, it receives a preference and determines the perception.<ref>Georg Eisner: ''[http://www.eisner-georg.ch/Andere/Perspektive/Perspektiven.pdf Perspektive und Visuelles System – Wege zur Wahrnehmung des Raumes]'' pp. 102–103</ref>
<gallery>
Perspektivisches Sehen und Interpretation.png|Context-dependent interpretation of the size
08913-Perspective Run.jpg|Shots at different distances
Study in Vanishing Perspective.jpg|The horizon line is at the height of the armrests.
Spatial vision and perspective.jpg|View from a window on the 2nd floor of a house
Mountain panorama in France 3.jpg|Mountain peak near the [[snow line]] and several mountain peaks above the snow line
ISS-40 Sicily and Italy.jpg|[[Earth#Size and shape|Earth curvature]]
</gallery>
In spatial vision, the horizontal line of sight can play a role. In the picture taken from the window of a house, the horizontal line of sight is at the level of the second floor (yellow line). Below this line, the further away objects are, the higher up in the [[visual field]] they appear. Above the horizontal line of sight, objects that are further away appear lower than those that are closer. To represent spatial impressions in [[Perspective (graphical)|graphical perspective]], one can use a [[vanishing point]].<ref>Georg Eisner: ''[http://www.eisner-georg.ch/Andere/Perspektive/Perspektiven.pdf Perspektive und Visuelles System – Wege zur Wahrnehmung des Raumes]'' page 181</ref> When looking at long [[geographical distance]]s, perspective effects also partially result from the angle of vision, but not only by this. In picture 5 of the series, in the background is [[Mont Blanc]], the highest mountain in the Alps. It appears lower than the mountain in front in the center of the picture. Measurements and calculations can be used to determine the proportion of the [[Earth#Size and shape|curvature of Earth]] in the [[subjectivity|subjectively]] perceived proportions.