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Fundamentals of Graphics Communication, 3/e
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Bertoline - Fundamentals of Graphics Communication Third Edition

Glossary S

Please click on the desired term below to view the glossary definition.
saturation  (n) A perceptual color quality indicating the ratio of the primary spectral wavelength (the hue) to all the wavelengths in the color. A high saturation color has a vivid hue, whereas a low saturation color approaches gray in appearance.
scalar value  (n) A quantitative data type that expresses magnitude but not direction.
scale  (n) A measuring tool used to calculate distances on a technical drawing. Scale can refer to both the physical tool, similar to a ruler, and the mathematical ratio used to calculate the size difference between the actual object and the drawn representation of the object. Scale lines in a visualization map the scale values to the graphic figure.
scale breaks  (n) Interruptions, or breaks, in a visualization scale, used to reduce large blank areas in the visualization created by widely dispersed data. Scale breaks allow a visualization to preserve a larger magnification by reducing the area required for the drawing.
scanner  (n) A computer input device used to capture information on paper and translate the information into a raster (bitmapped) computer image. Scanners can be used to convert a drawing created with traditional tools to a CAD drawing, to convert and enhance photographs in desktop publishing, or to input text information into the computer.
scatter plot  (n) A visualization technique that maps discrete values with point marks in either 2-D or 3-D space. A regression line is often included in the visualization to help recognize data trends.
schematic (logic) drawing  (n) A type of drawing or diagram commonly used in electronics to represent the logical and functional relationships of parts in an electronic assembly, circuit, or device. The drawing details the signal flow and control but not necessarily the spatial relationship of the final layout nor the actual point-to-point wiring that will be used. Special design symbols are used to represent the different types of electronic components.
SCM (supply chain management)  (n) An electronic alternative to the traditional paper chain, providing companies with a smarter, faster, more efficient way to get the right product to the right customer at the right time and price. Combines the power of the Internet with the latest technology, enabling participating suppliers to access up-to-date company information and enabling companies to better manage and track supply and demand.
screen angle  (n) The alignment angle of dots in halftone images. The angle of the dots in an image, especially when multiple screens are being used, is critical for avoiding illusionary and otherwise unwanted secondary patterns from appearing in the printed image.
screen coordinate system  (n) A coordinate system used to map graphics created by the computer software to the monitor. The coordinate system often has its origin in the upper left-hand corner of the screen, with the measurement unit in pixels.
screen print drawing  (n) See fabrication drawing.
secondary auxiliary view  (n) An auxiliary view projected from a primary auxiliary view. Secondary auxiliary views are used to depict oblique surfaces in their true size and shape.
section assembly  (n) An assembly drawing that provides a general graphic description of the interior shape of an assembly by passing a cutting plane through the assembly. The section assembly is usually a multiview drawing of all the assembled parts, with one view in full section. Other types of sections can also be used, such as broken-out and half sections.
section drawings  (n) Drawings containing views in which portions of the object have been removed. Section drawings typically depict the cutting plane used to define the removed material in a view adjacent to the actual section view. The section view depicts the cut surfaces with section line symbols.
section lines  (n) A line used to represent surfaces of an object cut by a cutting plane in section views. Section lines are drawn in a number of patterns (symbols) corresponding to the type of material being sectioned.
serial slices  (n) A visualization technique based on sectioning. A 3-D object is reduced to a series of 2-D images by representing two of the geometric dimensions in all slices, and each slice represents a discrete value range for the third geometric dimension.
servicing  (v) An activity that supports the installation, training, maintenance, and repair of a product or structure for the consumer. Technical illustrations are found in manuals used to support servicing activities.
set screw  (n) A mechanical threaded fastener, with or without a head, used to prevent rotation or movement between parts, such as a shaft and a collar. Set screws have special types of points for different applications.
shading  (v) A rendering technique simulating the effect of light on the surface of an object. The angular relationship between the light and the surface results in a variance in the value (darkness/lightness) of the surface. Abrupt changes in value typically indicate an edge between surfaces (faces).
shadow casting  (v) A rendering technique used to simulate shadows cast by (a) light source(s). Based on methods similar to hidden surface removal, the direction of the light rays is used to calculate which surfaces are nearest to the light source (and thus generate the shadow) and which are behind the near surfaces (and thus receive the shadow).
shaft basis  (n) A tolerancing technique used to define a system of fits and based on the basic size as being the maximum size of the shaft.
shape  (n) The internal spatial relationship of vertices and edges that make up a face or the arrangement of faces on an object. Examples of characteristics used to describe a face are the number of edges (sides), the angle between edges, and the ordering of edges around the perimeter. Shape is independent of overall scale but not of viewpoint.
SI  (n) Acronym for System Internationale (i.e., International System of Units), the metric measurement system. For technical drawings using the SI units, the millimeter (mm), meter (m), and the kilometer (km) are the most common units of measure. The international organization that established the metric standard is the International Standards Organization (ISO).
single-curved surface  (n) A surface that curves in only one dimension. A cylinder is an example of a single-curved surface. Single-curved surfaces can be developed without distorting or altering the topology of any of the faces.
single-line drawing  (n) See piping drawing.
size  (n) The spatial dimension of an object. When used with a dimension (i.e., inches, centimeters), size refers to an absolute measurement. Size can also be used in a relative sense to compare features or objects.
sketch modelers  (n) A term used to describe computer modeling systems used in the ideation phase of the design process. Sketch modelers are defined by their ability to produce approximately accurate models quickly and easily.
skew lines  (n) Nonintersecting, nonparallel lines in 3-D space. The relationship of skew lines, such as the shortest distance (clearance), can be calculated using descriptive geometry techniques.
software  (n) A set of coded instructions (programs) used to control the operation of a computer. Software is often grouped into categories, such as operating systems (e.g., MS-DOS), application programs (e.g., the CAD program), and utilities (e.g., security programs).
solid geometry  (n) The geometry of 3-D objects, such as cylinders, cubes, and spheres, and their relationships.
specular reflection  (n) Light reflecting from a surface at the same angle at which it contacted the surface. With a perfect mirror, 100 percent of the light is reflected in this manner. Specular refections are responsible for highlighting, or hot spots, seen on real objects and rendered models.
spherical coordinates  (n) Coordinates used to locate points on a spherical surface. Spherical coordinates are described by specifying a distance and an angle from the origin measured in the X–Y plane and then an angle from the X–Y plane.
spiral  (n) A curved line that begins at an origin point, moves further away from the origin, and decreases in curvature as it travels around the origin. A spiral is sometimes referred to as a spiral of Archimedes.
spline  (n or v) A free-form curve that connects a series of control points with a smooth curve. Changing a control point results in a change in the curve. The term also describes the process of connecting points to create a curve. B-spline and Bezier curves are examples of spline curves.
spooling drawing  (n) A piping drawing that gives the information necessary for the construction of a subassembly of an overall piping system. These drawings are used off site to fabricate subassemblies that can then be taken to the project site for final assembly.
spot enlargements  (n) Drawings used in conjunction with larger technical illustrations of parts or assemblies to show a clearer view of critical features. Spot enlargements typically use a combination of increased scale, reverse views, and sectioning to aid in viewing a feature. The enlargement is usually on the same sheet as the overall illustration, is isolated by ruled lines, and is keyed back to the overall drawing by a leader or a separate callout.
spot light source  (n) A light source located at a specified point and orientation in space. In rendering, a spot light source is usually close to the model. Besides a location and an orientation, the user also specifies an angle of dispersion to create a cone of light. A flashlight is analogous to a spot light source.
spring  (n) A mechanical device, often in the form of a helix, that expands or contracts due to pressure or force. Springs are classified as compression, tension, extension, flat, and constant force. A spring is further classified by the material, gage, spring index, direction of the helix, and type of ends.
Standard for the Transfer and Exchange of Product Model Data  (n) See STEP.
standards  (n) Sets of rules that allow for the clear communication of technical ideas by governing how parts are made and represented in technical drawings. In the United States, the American National Standards Institute (ANSI) is the governing body that sets the standards used for engineering and technical drawings.
statics  (n) An area of applied physics that deals with the analysis of forces in bodies (parts) at rest (in equilibrium).
station point  (n) The eyepoint of the observer in a perspective drawing. The location of the station point relative to the object, and the horizon line determines the perspective viewpoint (i.e., bird’s eye, human’s eye, etc.).
statistical process control  (n) The system used for the selection of parts that are then measured for accuracy. Mathematical statistics is the tool used to analyze the measurements of the randomly selected parts. Consistent and accurate measurements will indicate when a machine tool must be maintained or adjusted during the manufacturing cycle.
steel  (n) An alloy of iron, containing various amounts of carbon, manganese, and one or more other elements, such as sulfur, nickel, silicon, phosphorus, chromium, molybdenum, and vanadium. These elements, when combined with iron, form different types of steels with varying properties.
STEP  (n) An acronym for Standard for the Transfer and Exchange of Product Model Data, a neutral data exchange standard developed by the ISO. The development of this standard is an attempt to integrate the European standards and IGES and to embody a larger, more flexible subset of information.
stereolithography  (n) A rapid prototyping technique in which the model is first decomposed into a series of thin layers and then reconstructed. A pair of light beams moves a focal point about in a vat of photosensitive polymer, tracing one layer at a time. Once one layer of polymer has been hardened by the light beams, the light beams trace the next layer up.
straight line  (n) A line generated by a point moving in a constant direction. Straight lines can be either infinite or finite in length. A finite straight line is an entity of specific length but no depth or breadth. An infinite straight line is an entity of unspecified length but no depth or breadth.
straightness  (n) A form control for geometric dimensioning and tolerancing. Straightness means that all points on a part have the same direction throughout its length. Straightness also refers to the path describing the shortest (uniform) path between two points.
streamlines  (n) Line marks, usually curved, used in visualizations to depict the path of flow of a fluid or gas. Streamlines are used in aerodynamic studies to evaluate the flow of air or water around a proposed design.
stretching  (v) A modification technique that changes the location of individual points or groups of connected points of an object. Stretching changes the geometry but not the topology of the polygon or face of the solid. If this technique is used on a 3-D solid, it is sometimes referred to as tweaking.
stud  (n) A mechanical fastening device that consists of a cylindrical rod threaded on one or both ends and that screws into a mating part. A nut may be used on one end.
subassembly  (n) A logical grouping of parts that are only part of the total assembly. Often, a subassembly is a working mechanism in and of itself, but it works in concert with other parts to form the complete assembly.
subtractive  (adj. or v) A process or state in which elements are removed from each other. Subtractive is the opposite of additive.
subtractive primaries  (n) The three primary colors cyan, magenta, and yellow. Color systems using these primaries work on the principle of subtracting spectral wavelengths from the light energy to create new colors. These systems are used in ink-based graphics, specifically four-color printing (the fourth color being black). The complementary colors are the additive primaries: red, green, and blue.
successive auxiliary view  (n) An auxiliary view of an object created by projecting from other auxiliary views. With the use of successive auxiliary views (e.g., secondary auxiliary, tertiary auxiliary, etc.), it is possible to create virtually any view of an object.
surface  (n) A finite portion of a plane, or the outer face of an object, bounded by an identifiable perimeter. A surface represents the path of a moving straight or curved line, called a generatrix. The path that the generatrix travels is the directrix. In a 3-D model, the topological equivalent of a surface is a face.
surface plot  (n) A 3-D visualization technique used with two independent variables (X and Y) and one dependent variable (Z). A surface connecting the data points represents the mapping of the independent and dependent variables. Shading and other rendering techniques are often used to help visualize the surface.
sweeping  (n) A 3-D modeling operation in which a closed polygon, called a profile, is drawn on the workplane (the U–V plane) and is transformed along a defined path. The sweeping technique is procedural in nature in that instructions are given as to how far and in what direction the sweep of the profile is to occur in order to create the solid.
symmetrical  (adj.) A quality in which all the features on either side of a point, line, or plane are identical. The matching features form balanced, mirror images.
system  (n) An orderly arrangement of parts that are combined to serve the same general function. Examples are the arrangement of the assembly process in a factory; the heating, ventilating, and air conditioning (HVAC) system in a structure; and the electrical system in an automobile.