PAU Technical Drawing Applied to Plastic Arts (Cantabria) flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Golden ratio value

The ratio of a segment divided in extreme and mean proportion, approximately 1.618, obtained as (1+√5)/2 and used to set harmonic proportions in composition.

Thales' theorem

A line parallel to one side of a triangle divides the other two sides proportionally, allowing a segment to be divided into equal or given parts.

Inscribed angle in semicircle

Any angle whose vertex lies on a circle and whose sides pass through the ends of a diameter measures exactly 90 degrees, a standard construction for right angles.

Regular polygon side formula

For a regular polygon of n sides inscribed in a circle of radius R, each side equals 2R·sin(180°/n); the apothem equals R·cos(180°/n).

Root-two rectangle

A rectangle whose sides are in ratio 1:√2, the basis of ISO A-series paper, which keeps the same proportion when halved along the long side.

Circle tangent to two lines

The centre of any circle tangent to two intersecting lines lies on one of the angle bisectors; the radius is the perpendicular distance to either line.

First-angle projection layout

In first-angle (European) projection the object sits between observer and plane, so the top view is drawn below the front view and the left view to its right.

Third-angle projection layout

In third-angle projection the plane lies between observer and object, so the top view is drawn above the front view and the right view to its right.

True length from projections

The real length of a segment equals the square root of the sum of the squared differences in the three coordinates read from its two orthographic views.

Edge view of a plane

A plane appears as a straight line in any view whose projection direction lies within that plane; a further view perpendicular to it shows true shape.

Change of projection plane

Introducing a new plane parallel to a line or plane gives its true length or true shape in a single step, avoiding repeated auxiliary constructions.

Hidden line convention

Edges not visible from the viewing direction are drawn as dashed lines; in multiview work a point is hidden when another point of greater depth projects onto it.

Isometric axonometry

A parallel projection with three axes at 120 degrees and equal foreshortening on all three; along-axis lengths are drawn at about 0.816 of true size.

Cavalier oblique projection

An oblique axonometry in which the frontal face is drawn true shape and the receding axis, usually at 45 degrees, carries depth at full or half scale.

Vanishing point rule

The vanishing point of a family of parallel lines is where the picture plane meets the line through the station point parallel to that family.

One-point versus two-point perspective

One-point perspective keeps a principal face parallel to the picture plane with a single vanishing point; two-point turns the object so two vanishing points share the horizon.

Perspective height formula

An object of real height h at distance d from the picture plane appears with height h' = h·(d0/d), where d0 is the station point distance.

Circle in perspective

A circle projects as an ellipse in conical perspective; its major axis tilts away from the horizontal except in special positions relative to eye level.

ISO A0 sheet

A0 measures 841 by 1189 millimetres and one square metre in area; each successive size halves the area while keeping the 1:√2 ratio.

Scale ratio definition

Scale equals drawing length divided by real length; 1:50 means one unit on paper represents fifty real units, and dimension figures always state real size.

Line types hierarchy

Continuous thick lines show visible outlines, dashed lines hidden edges, chain thin lines axes and symmetry, continuous thin lines dimensions and extension lines.

Radius and diameter symbols

A radius is prefixed R, a diameter ⌀, a square □ and a spherical radius SR; a count before the symbol, as in 4×⌀8, states repetition.

Graphic scale bar

A drawn bar subdivided into units that remains valid when the sheet is photocopied or resized, unlike a numerical ratio printed alone.

First-angle symbol

The distinguishing symbol shows a truncated cone with its small end facing the front view, indicating that views are placed opposite to their viewing direction.

Rule of thirds

A compositional grid dividing the frame into nine equal parts; placing key elements on the lines or intersections produces balance and clear focal points.

Gestalt proximity law

Elements placed close together are perceived as a group, so spacing alone can create structure in a composition without drawn borders.

Figure-ground contrast

A shape reads as a figure only when its value differs enough from the background; equal-value adjacent areas merge and lose their edge.

Depth cues in drawing

Overlap, relative size, texture gradient, convergence of parallels and atmospheric fading are the pictorial cues that make a flat image read as space.

Dynamic symmetry grid

A proportional system based on root rectangles whose subdivisions repeat the same ratio throughout, keeping all parts of a composition harmonically related.

Exploded axonometric

An axonometric view in which parts are separated along dashed assembly axes while keeping their orientation, showing how a product fits together.

Section and elevation datum

Heights in a spatial drawing are dimensioned from a fixed datum, normally finished floor level, so ceiling height and sightlines can be read consistently.

Technical versus presentation drawing

Dimensioned orthographic drawings are the measurable, contractual record; perspective renderings convey atmosphere and must never be scaled for dimensions.

Drawing revision control

Each sheet carries a revision number, date and cloud marking the change, so anyone can identify the current version and what was altered.