GRAPHIC GRAPHIC EXPRESSIONEXPRESSION

GRAPHIC GRAPHIC EXPRESSIONEXPRESSION

Lesson 2. 1st termLesson 2. 1st term

Perspective in drawings• We use projection drawings to represent 3D

objects in two dimensions (our paper)• There are two types of projections:

Cylindrical (Orthogonal) Conic

(x, y, z)

VPVP

•No distorsion

•Vanishing point (VP) far away

•Objects are distorted in the same way our eyes see them

•Vanishing point close

First angle projection• Cylindrical projection composed of

three views (taken from very far away) of the object:

side

front

top

First angle projection: result

front side

top

Oblique projection• We represent one of

the faces (mathing with X and Y axis) in true dimension and the others are distorted.

Y

Z

X

Representing objects in oblique projection

Y

Z

X

We have to consider the X, Y and Z axis.

We first draw the front face of the figure (X and Y axis

Then we draw the sides corresponding with the z axis with a reduction coefficient of 1/2

We finally close the figure with the lines corresponding to the back of the figure

Axonometric projection _ Isometric projection

• Axonometric projection shows an object from the corner so we see its three sides

• Objects seem distorted because the same scale is used for all features

• One axis is drawn vertical and the others are at an angle.

120º

120º 120º

Isometric projection

Drawing objects in isometric projection

120º

120º 120º

Isometric projection

We draw according the axis at 120º angles

We first draw a figure’s corner

Second we draw the lines which correspond to the sides next to the corner, corresponding with Z axis

Then we draw the lines corresponding to the left and rigth cornersWe first draw a figure’s corner

Two point perspective

2 VP1 VP

Draw an horizontal line across the page and mark two vanishing points: VP1 and VP2

Draw one corner of the box: vertical lineDraw the construction lines from the top and the botton of the corner to the vanishing point

Draw two vertical lines corresponding to the left and rigth corners. They go from the top to the botton lines

Draw the last construction lines from the top and the botton of the other corners

Complete the box using the construction lines

Single point perspective

First draw the front of the cube. Then add a vanishing point (X)

Draw thin construction lines from each corner to the vanishing point

Draw the lines which correspond to the back of the figure

Draw the rest of the figure over the segments of the construction lines

VP

Dimensioning• To dimension means “to indicate the

real size of an object in its drawing”

45

70

25

50

Scale

Magnitudes and units• Magnitude is a physical

property which we can measure / determine / quantify: i.e: length, mass,…

• Units are the symbols which go after a number and identify the magnitude we refer to

Types of magnitudes• Fundamental: we can express or

determine them with a direct measurement: there are seven: mass (M), length (L), time (t)

• Derived (derivadas): they are obtained by combining the fundamental magnitudes: force, volume, surface…