Architectural Graphics, Anthropometrics and Space Standards

Visual composition principles

Visual composition principles describe how linear and planar elements are arranged in a two-dimensional design so that the viewer reads a clear structure. Interlacing is the weaving of linear elements so that each one passes alternately over and under the elements it crosses, which produces a flat woven pattern. Interlocking describes elements linked together in three dimensions, as in chain links, and interpenetrating describes forms that pass through one another in space. Intersecting only means that lines cross without any specified over-and-under pattern.

Gestalt principles explain how the eye groups elements into organized wholes. The main ones are proximity, which groups nearby elements, similarity, which groups alike elements, continuity, which favours smooth paths, closure, which completes incomplete figures, and figure-ground separation. Scale and proportion are compositional concepts, and grain and texture are surface qualities, so neither belongs to the Gestalt set.

Francis Ching's principles of organization explain how forms and spaces are ordered. A datum is a line, plane or volume whose continuity and regularity organize a pattern of forms and spaces. Symmetry is the balanced distribution of equivalent forms about a common line or point. Hierarchy is the significance given to a form or space by its size, shape or placement relative to others. Rhythm is the use of recurring patterns to organize a series of like forms or spaces.

Universal design principles

Universal design is the design of environments and products that can be used by the widest range of people without adaptation. The seven principles were formulated by the Center for Universal Design at North Carolina State University. They are equitable use, flexibility in use, simple and intuitive use, perceptible information, tolerance for error, low physical effort, and size and space for approach and use.

Perceptible information means that necessary information is communicated effectively, regardless of the user's sensory abilities, for example by combining pictorial, verbal and tactile cues. Simple and intuitive use means that the design is easy to understand regardless of the user's experience, knowledge or language. Terms such as occult balance are not principles of universal design.

Tolerance for error is the principle that minimizes hazards and adverse consequences of accidental or unintended actions, for example through warnings, fail-safe features and isolation of hazardous elements. Flexibility in use concerns accommodating a range of individual preferences and abilities, so it is a different principle.

For wheelchair access, the National Building Code of India 2016 specifies the clear opening of a doorway. A single wheelchair must be able to pass through, and the minimum clear opening for that purpose is 900 mm. Larger widths are needed where more than one wheelchair or extra manoeuvring space must be provided.

Geometric curves in drawing

A hypocycloid is the curve traced by a fixed point on a circle that rolls without slipping on the inside of a larger fixed circle. The corresponding curve for a circle rolling on the outside is the epicycloid. When the rolling circle has one quarter the radius of the fixed circle, the hypocycloid becomes a four-cusped curve called the astroid. A helix is a three-dimensional spiral wound on a cylinder, an involute is traced by the end of a taut string unwinding from a circle, and a hyperbola is a conic section, so none of these is generated by a rolling circle.

Hogarth, in The Analysis of Beauty (1753), described the line of beauty as a serpentine S-shaped curve that is neither straight nor zigzag. It is a gently undulating double curve, which he regarded as the most graceful linear form. Straight horizontal lines express stability and zigzag lines express sharp, sudden movement.

Colour wheel harmonies

A colour harmony is a scheme of hues chosen from the colour wheel according to their angular positions. A triad uses three hues spaced equally around the wheel, at intervals of 120^\circ. Analogous schemes use neighbouring hues that sit close together on the wheel. A complementary scheme uses two hues located 180^\circ apart. A split-complementary scheme uses a base hue together with the two hues adjacent to its complement.

• Triad — three hues at 120^\circ intervals. Ex) Using red, yellow and blue together for a bold, balanced palette.
• Analogous — neighbouring hues. Ex) Green, yellow-green and yellow for a calm facade.

Primary and secondary colours depend on the colour system. In the additive system, which mixes coloured light, the primaries are red, green and blue, and the secondaries are cyan, magenta and yellow, each formed by mixing two primaries. In the subtractive system used for pigments, the primaries are cyan, magenta and yellow, and the secondaries are red, green and blue.

Vector graphics software

Vector graphics represent images as mathematical descriptions of points, lines and curves, so they can be scaled without loss of quality. Raster graphics represent images as grids of pixels and lose sharpness when enlarged. Inkscape is an open-source vector editor that creates and edits Scalable Vector Graphics (SVG) files. Other software serves different purposes: Odeon is for room acoustics simulation, Adobe Dreamweaver is for web development, and DesignBuilder is for building energy and daylighting simulation.

In AutoCAD, surface commands create meshes from curves in different ways. TABSURF sweeps a profile curve along a straight direction vector to form a tabulated surface, as in an extrusion along a line. REVSURF revolves a curve about an axis. RULESURF creates a ruled surface between two curves by joining corresponding points with straight lines. EDGESURF creates a Coons-type patch from four edge curves.

Golden ratio proportion

The golden ratio, denoted \varphi, is the positive root of \varphi^2=\varphi+1, given by \varphi=\frac{1+\sqrt{5}}{2}\approx 1.618. It expresses a proportion in which the whole is to the larger part as the larger part is to the smaller part, so the ratio of smaller to larger part is 1:\varphi, equivalently 2:(1+\sqrt{5}).

Other common proportions should not be confused with it. The ratio 1:\sqrt{2} is the proportion of ISO paper sizes, 1:1 denotes equal sides, and 16:9 is a standard widescreen aspect ratio.

The golden ratio has useful algebraic relations: \frac{1}{\varphi}=\varphi-1\approx 0.618 and \varphi^2=\varphi+1\approx 2.618. In a golden mean construction that begins with a unit square and adds squares along the rectangle, the lengths grow by these powers of \varphi, so a derived segment of a golden construction can equal \varphi^2 \approx 2.618 cm when the base square has a 1 cm side.

Map scale area conversion

A map scale of 1:N means that one unit of length on the drawing represents N units on the ground. Because area is two-dimensional, the area scale is the square of the linear scale, so a ground area A appears on the drawing as A/N^2. Converting units first is essential, since 1\ \text{m}^2 = 10^4\ \text{cm}^2 and 1 hectare = 10^4\ \text{m}^2.

Example: a plot of 400\ \text{m}^2 drawn at 1:200 has a drawing area of \frac{4\times10^6\ \text{cm}^2}{200^2}=100\ \text{cm}^2. Conversely, if a drawn area is known, the ground area is the drawn area multiplied by N^2, and the linear scale is the square root of the area ratio of drawing to ground.

Room access and circulation diagrams

An access diagram, also called a justified graph, shows how rooms are reached from an entry point. Each room is a node and each door or direct connection is a link. The entry is placed at the top of the graph, and rooms are arranged by their depth, meaning the number of steps from the entry. A room that opens directly onto the entry is at depth one, and a room reached only through another room appears below it.

In planning of specialized buildings such as an operation theatre, the circulation is organized into zones of increasing cleanliness. Staff change clothes in the dress change area before entering the sterile zone. Patients move from the corridor through the pre-operative space into the operation theatre and return through the post-operative space. Soiled materials leave the theatre through the dirty utility room so that they do not cross the clean route.

Architectural software tools

Architectural and engineering software is grouped by function. Raster graphics editors such as GIMP edit pixel images. Energy modelling platforms such as OpenStudio simulate the energy performance of whole buildings. Visual programming interfaces such as Grasshopper let designers build parametric models by connecting graphical components. Structural analysis and design programs such as STAAD compute forces and stresses in frames and members. Radiance is a lighting and daylighting simulation tool.