Unit: Drawing in Perspective

Additive Shape Building– is one of two basic approaches to creating complex shapes in which simple shapes are combined to make larger forms.

Angle of Incidence– is the angle at which a subject is positioned in relation to a reflective surface or mirror.

Angle of Reflection– is the angle at which a subject’s reflection appears on the reflective surface or mirror.

Atmospheric Perspective– the perception of depth resulting from the color-shifting effects of the atmosphere. The more particulate matter or the greater the distance between the viewer and the subject, the more muted in value, muted in saturation, and cooler in hue the subject will appear.

Center of Vision (COV)– The center of vision is the endpoint of the viewer’s line of sight, indicating the direction of the viewer’s gaze. The center of vision is often, but not always, located on the horizon line.

Compositional Frame – The compositional frame is a drawing’s outer edge that crops the scene and delineates what is presented as part of the final image versus what is relegated to the margins. Oftentimes vanishing points are outside of the compositional frame. When employing a cone of vision, you must inscribe the frame within the cone.

Cone of Vision– The cone of vision is the range of sight of the viewer, with the center of vision as its center. Subjects rendered outside of the cone of vision appear distorted. Normal monocular vision is a 60-degree cone of vision, however, artists more often employ a 90-degree cone of vision to maximize useable composition area.

Convergence– is one of three principles of linear perspective in which receding forms appear increasingly closer together.

Diagonal vanishing point– is the point where a set of parallel diagonals receding from the viewer appears to converge. We abbreviate as DVP.

Diminution– is one of three principles of linear perspective in which receding forms appear increasingly smaller.

Elevation view– is a side view of the subject on a two- dimensional grid. An elevation view depicts the relative height and location of forms.

Field of Sight– is a concept specific to five-point perspective. It is analogous to the line of sight used in one-, two-, and three-point perspective. Field of sight represents an area of observation where the viewer simultaneously observes 180 degrees of the scene in all directions.

Five-Point Perspective– is a point of view in which five sets of parallel edges recede from the viewer and appear to converge at five vanishing points. A rectangular prism is assumed.

Focal Point– is an area of interest, detail, contrast, or anomaly within a composition that draws an observer’s attention. Focal point is a tool used by artists and designers to describe or express a visual idea or narrative, and it should not be confused with a vanishing point.

Foreshortening– is one of three principles of linear perspective in which receding planes appear to shorten.

Ground Line (GL)– represents the ground plane in an elevation view. The ground line is located below the horizon line, and the distance between the ground line and horizon line indicates the height of the viewer with respect to the height of the subject.

Ground Plane– is the two-dimensional horizontal plane below the horizon line, representing the ground or floor.

Horizon Line (HL)– is a horizontal line where the sky appears to meet the ground. The horizon line is an illusion and represents the place where diminution, convergence, and foreshortening are infinite.

Isosceles Triangle– is a three-sided shape with two sides of equal length.

Law of Vanishing Points– says that any set of parallel edges receding from the viewer will appear to meet at a vanishing point.

Light Source Vanishing Point (LVP)– is one of two special types of vanishing points used to create cast shadows. The light source vanishing point is the location where the light converges, aka the point of origin of the light source itself.

Linear Perspective– is a geometric method of depicting three-dimensional subjects in a two-dimensional format. Linear perspective uses rectangular planes and prisms to model monocular vision, creating an illusion of depth.

Line of Sight– represents the direction of the viewer’s gaze and is usually perpendicular to the horizon line and always points to the center of vision.

Multi-Point Perspective– is a form of linear perspective that uses five or more vanishing points to build the image. Multi-point perspectives mimic fish-eye (180 degree) and panoramic (360 degree) views.

Monocular Vision– is sight from one eye with the other eye closed. Unlike binocular vision, which combines sight from both eyes for depth perception, monocular vision can be modeled with linear perspective.

One-Point Perspective– is a point of view in which one set of parallel edges recedes from the viewer and appears to converge at a single vanishing point. A rectangular prism is assumed.

Orthogonal Lines– are diagonal lines that can be drawn along receding parallel lines (or rows of objects) to the vanishing point.

Parallel lines– lines that are equal distance apart and never meet.

Perpendicular lines– lines that are at a right angle to another line.

Perpendicular– an angle that is a 90-degrees.

Perspective Center– is the middle point of a rectangular plane in perspective, found at the intersection of the plane’s diagonals.

Perspective Grid– is a three-dimensional grid in perspective that can be based on either square or rectangular planes. There are one-point, two-point, three-point, four-point, five-point, and infinite-point perspective grids.

Perspective Scaling– is the process of repeating a form within a composition while maintaining its size and relative proportion.

Picture Plane (PP)– is the two-dimensional surface onto which three-dimensional space is translated. It is analogous to a window or viewfinder situated between the viewer and the subject. Think of the picture plane as standing in for the piece of paper onto which the subject will be drawn. Positioned between the viewer and the subject, the picture plane is always perpendicular to the viewer’s line of sight.

Plan View– is a top-down view of the subject and ground plane on a two-dimensional grid. A plan view depicts the relative width, depth, and location of forms. Floor plans and maps are examples of a plan view.

Point of View– is a particular view of a subject, as defined by the viewer’s station point and center of vision in relation to the subject. Observable linear perspective categorizes all points of view into one of three major types: one-point, two-point, and three-point.

Projected Station Point– is the projection of the viewer’s three-dimensional location in space onto the two-dimensional surface of the perspective drawing. In perspective, the projection is understood and projected station points are functionally synonymous with station points.

Rectangular Plane– is a flat surface that has two dimensions and 90-degree angles at each corner.

Rectangular Prism– is a form that has three dimensions and 90-degree angles at each corner.

Renaissance– means rebirth. It refers to the revival or interest in the arts of the classic Roman and Greek period. It occurred between the 14th and 17th centuries and saw the birth and development of perspective and shading to create the illusion of three dimensions on a two-dimensional surface.

Linear Perspective– a geometric system of drawing that shows the illusion of depth on a flat surface.

Shading– or rendering, is the application of value. Pencil shading techniques include toning, blending, erasing, hatching, cross-hatching, contouring, stippling, and scribbling.

Shadow Vanishing Point (SVP)– The shadow vanishing point, one of two special types of vanishing points used to create cast shadows, is the location where the edges of a cast shadow converge. The shadow vanishing point is always located directly below the light source.

Slope– is the gradient or steepness of a plane, as measured by an angle formed at a reference vertex. Sloping planes have special vanishing points.

Station Point (SP)– is the fixed location of the viewer.

Stylization– is representing natural objects in a particular style that can be a popular style or an individual style. An example would be Edvard munch's "The Scream" in which the facial features and objects in the painting are simplified and elongated.

Subtractive shape building– one of two basic approaches to creating complex shapes, subtracts simple shapes from a larger form.

Three-point Perspective– is a point of view in which the three sets of parallel edges recede from the viewer and appear to converge at three different vanishing points. A rectangular prism is assumed.

Two-point Perspective– is a point of view in which two sets of parallel edges recede from the viewer and appear to converge at two separate vanishing points. A rectangular prism is assumed.

Value– is the relative lightness or darkness of a form. It describes the location of a light source, the shape of a form, and the texture of a surface.

Value Mapping– is a technique for planning areas of value within an entire composition using a value scale and referencing the light source(s).

Vanishing Point (VP)– is the point where a set of parallel edges receding from the viewer appear to meet.

Vertex– is the point, or corner, of two intersecting lines used to measure angles.

Vertical Axis Line– is perpendicular to the horizon line and intersects a vanishing point; this line is used to locate diagonal vanishing points for vertical planes.