Canary Islands PAU Technical Drawing Applied to Plastic Arts & Design II flashcards

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

Focal property of ellipse

For any point P on an ellipse, the sum of distances to the two foci is constant and equals the major axis 2a. This property generates the curve and underlies tangent constructions.

Eccentricity of a conic

Ratio e = c/a between focal distance and semi-major axis. e < 1 gives an ellipse, e = 1 a parabola, e > 1 a hyperbola; e = 0 is a circle.

Tangent from external point to circle

Draw the circle with diameter OP, where O is the centre and P the external point. Its intersections with the given circle are the two tangency points.

Four-centre oval

Compass construction using four circular arcs that approximates an ellipse. It is tangent-continuous but not a true ellipse, since curvature is not continuous in the mathematical sense.

Constant-angle arc locus

Locus of points seeing segment AB under angle α consists of two arcs through A and B whose centres lie on the perpendicular bisector at distance (AB/2)/tan(α/2).

True length by rotation

Rotate a segment about an axis perpendicular to a projection plane until it is parallel to that plane; the new projection shows the true length of the segment.

Line perpendicular to plane

A line is perpendicular to a plane when its horizontal projection is perpendicular to the plane's horizontal trace and its vertical projection to the vertical trace.

Auxiliary plane method

To find a line-plane intersection, pass a projecting plane through the line, intersect it with the given plane, and locate where that intersection line crosses the original line.

Traces of a plane

The lines where a plane cuts the reference planes. In dihedral projection they are the horizontal trace and the vertical trace, meeting on the reference line.

Euler polyhedron formula

For any convex polyhedron, vertices minus edges plus faces equals two: V − E + F = 2. It holds for all five regular polyhedra.

Cone lateral development

A circular sector of radius equal to the generatrix g, with angle α = 360°·r/g, where r is the base radius. Truncated cones need rotated generatrices for true lengths.

Cylinder development

The lateral surface unfolds into a rectangle whose width equals the base circumference 2πr and whose height equals the cylinder height h.

Section of cone by plane

The section is an ellipse if the plane cuts every generatrix, a parabola if parallel to one generatrix, and a hyperbola if it cuts both nappes of the cone.

Penetration of two solids

The intersection curve is found point by point where edges or generatrices of one solid meet the surface of the other, using auxiliary planes.

Isometric scale factor

True isometric projection foreshortens all three axes by √(2/3) ≈ 0.816. Isometric drawing convention instead uses full scale along the axes for simplicity.

Vanishing point rule

In conical perspective, any set of parallel lines in space converges to a single vanishing point. Lines parallel to the picture plane have no finite vanishing point.

Horizon line equals eye level

The horizon line on the picture plane sits at the observer's eye height. Objects below it show their top faces; objects above it show their undersides.

Cabinet and cavaliera projection

Oblique axonometric systems with the front face in true shape. Cabinet halves the receding axis scale; cavaliera keeps full scale on all three axes.

Station point in perspective

The observer's eye position in conical perspective. Its distance from the picture plane fixes the cone of vision and the spacing of vanishing points.

First-angle projection

The object lies between observer and projection plane. The view placed to the right of the front view is therefore the left-side view.

Hatching in section views

Cut surfaces are hatched with thin parallel lines, usually at 45°. Adjacent parts in an assembly use different directions or spacings to remain distinguishable.

Dimension line rules

Dimension lines run parallel to the measured edge with arrowheads at both ends; extension lines are perpendicular to it; values in millimetres carry no unit symbol.

ISO A sheet series

A0 has an area of one square metre; each following size halves the area while keeping the √2 side ratio. A4 measures 210 × 297 mm.

Scale notation

A scale is the ratio of drawing length to real length, drawing value first: 1:50 reduces, 2:1 enlarges. It is stated in the title block.

Golden ratio

A proportion where the whole relates to the larger part as the larger part relates to the smaller: φ ≈ 1.618. It underlies many proportional grids and page formats.

Rule of thirds

Divide the frame into a 3×3 grid and place key elements on the intersections or along the lines to obtain a balanced, dynamic composition.

Signage legibility rule

A rough minimum cap height for legible signage is viewing distance in metres multiplied by 2.5 mm, under normal lighting and contrast conditions.

WCAG contrast minimum

WCAG AA requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text to remain readable for low-vision users.

Baseline grid

A grid of evenly spaced horizontal lines to which all text baselines align, keeping lines of type consistent across columns and pages of a layout.

Ergonomic seat height

Typical seat height for chairs is 43–45 cm, with table height around 72–75 cm; these figures anchor furniture and interior design projects.

Exploded view

A drawing showing the parts of an assembly separated along their assembly axes, revealing order and joining method; often paired with a bill of materials.

Project documentation set

General arrangement drawing, exploded view, dimensioned detail views, material and finish notes, and a bill of materials, presented together with the concept rationale.