Title: Vanishing point
Content:  of some plane, say α , is obtained by the intersection of the image plane with another plane, say β , parallel to the plane of interest ( α ), passing through the camera center. For different sets of lines parallel to this plane α , their respective vanishing points will lie on this vanishing line. The horizon line is a theoretical line that represents the eye level of the observer. If the object is below the horizon line, its vanishing lines angle up to the horizon line. If the object is above, they slope down. All vanishing lines end at the horizon line.
Title: Horizon
Content:   The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether it intersects the relevant body's surface or not. The true horizon is actually a theoretical line, which can only be observed to any degree of accuracy when it lies along a relatively smooth surface such as that of Earth's oceans. At many locations, this line is obscured by terrain, and on Earth it can also be obscured by life forms 
Title: Vanishing point
Content:  As a vanishing point originates in a line, so a vanishing line originates in a plane α that is not parallel to the picture π . Given the eye point O , and β the plane parallel to α and lying on O , then the '''vanishing line of α ''' is β ∩ π . For example, when α is the ground plane and β is the horizon plane, then the vanishing line of α is the horizon line β ∩ π . Anderson notes, "Only one particular vanishing line occurs, often referred to as the "horizon". To put it simply, the vanishing 
Title: Horizon
Content:  and algebra have a simpler foundation than previously thought.  The horizon is a key feature of the picture plane in the science of graphical perspective. Assuming the picture plane stands vertical to ground, and P is the perpendicular projection of the eye point O on the picture plane, the horizon is defined as the horizontal line through P. The point P is the vanishing point of lines perpendicular to the picture. If S is another point on the horizon, then it is the vanishing point for all lines parallel to OS. But Brook Taylor (1719) indicated that the horizon plane determined by O and the horizon was like any other plane: The peculiar geometry of perspective where parallel lines converge in 
Title: Horizon
Content:  plane converge (when projected onto the picture plane) as their distance from the observer increases. For observers near sea level the difference between this geometrical horizon (which assumes a perfectly flat, infinite ground plane) and the true horizon (which assumes a spherical Earth surface) is imperceptible to the unaided eye (but for someone on a 1000-meter hill looking out to sea the true horizon will be about a degree below a horizontal line). In astronomy, the horizon is the horizontal plane through the eyes of the observer. It is the fundamental plane of the horizontal coordinate system, the locus of points that have an altitude of zero degrees. While similar in ways to the geometrical horizon, in this context a horizon may be considered to be a plane in space, rather than a line on a picture plane.
Title: Picture plane
Content: Given are an eye point O (from oculus), a horizontal plane of reference called the ground plane &gamma; and a picture plane &pi;... The line of intersection of &pi; and &gamma; is called the ground line and denoted GR. ... the orthogonal projection of O upon &pi; is called the principal vanishing point P...The line through P parallel to the ground line is called the horizon HZ In the technique of graphical perspective the picture plane has several features: The horizon frequently features vanishing points of lines appearing parallel in the foreground.
Title: Horizon
Content:  from the observer. For instance, in standard atmospheric conditions, for an observer with eye level above sea level by 1.70 m, the horizon is at a distance of about 5 km. When observed from very high standpoints, such as a space station, the horizon is much farther away and it encompasses a much larger area of Earth's surface. In this case, the horizon would no longer be a perfect circle, not even a plane curve such as an ellipse, especially when the observer is above the equator, as the Earth's surface can be better modeled as an ellipsoid than as a sphere.
Title: Vanishing point
Content:  1. Projections of two sets of parallel lines lying in some plane πA appear to converge, i.e. the vanishing point associated with that pair, on a horizon line, or vanishing line H formed by the intersection of the image plane with the plane parallel to πA and passing through the pinhole. Proof: Consider the ground plane π , as which is, for the sake of simplicity, orthogonal to the image plane. Also, consider a line L that lies in the plane π , which is defined by the equation ax + bz = d .Using perspective pinhole projections, a point on L projected on the image plane will have coordinates defined as, x′ = f·x⁄z = f·d − 
Title: Glossary of geography terms
Content:  with a narrow crest and steep, symmetrical slopes of nearly equal inclination on both flanks, especially one created by the erosion of an  which exposes homoclinal sedimentary rock strata. horizon: The apparent line that separates the ground from the sky, dividing all visible directions into two categories: those that intersect the Earth's surface and those that do not. When not obscured by buildings, trees, or mountains, the true horizon can be useful in navigation and determining positional orientation. horn: A formed by the back-to-back abutment of three or four adjacent, leaving a distinctly pyramidal peak. horst: A raised block of the Earth's, bounded by parallel or, that has been 
Title: Horizon
Content:  as trees and/or human constructs such as buildings. The resulting intersection of such obstructions with the sky is called the visible horizon. On Earth, when looking at a sea from a shore, the part of the sea closest to the horizon is called the offing. As of 2021, nearly all humans who have ever lived have not personally observed the horizon of any celestial body other than Earth's horizon, with the only exceptions being those Apollo astronauts who have traveled to the Moon and have thus also observed the lunar horizon in addition to the terrestrial horizon. In addition the horizons of several 

Question: if there is a line that lies parallel to the horizon it is said to be?
Answer: A vanishing point.