ENG 004 Lecture 4, Oct 9, 2012



Drawing Types

3D to 2D, 2D to 3D



Drawing Types

Projection theory is in Chapter 5

Projections and Perspective

One point perspective

One point perspective

Two point perspective

Two point perspective

Two point perspective

Parallel Projections

Parallel projection corresponds to a perspective projection with an infinite focal length (the distance from the image plane to the projection point)

Orthographic projection

Parallel project representation of a three dimensional object in two dimensions


To measure along axes.

Multiview Projections

Up to 6 views of an object are projected onto planes perpendicular to the coordinate axes. The view positions follow one of two schemes: First Angle or Third Angle

Pictorial Projections

Image of object from skewed direction to reveal all axes

Isometric, Dimetric, Trimetric

Axonometric Projections

Type of parallel projection, more specifically a type of orthographic projection, used to create a pictorial drawing of an object, where the object is rotated along one or more of its axes relative to the plane of projection

Isometric Projections

All three axes are equally foreshortened and angled 120 degrees apart.

Lines are parallel.

Isometric Projections

Isometric Limitations

Isometric Limitations

Orthographic Axonometric Multiview Projections

Third Angle Projection

Orthographic Multiview Projections

Orthographic Multiview Projections


Projects an image by intersecting parallel rays (projectors) from the three-dimensional source object with the drawing surface (projection plane).

θ is typically 45 degrees

x-y scales are the same

z scale is between 0 and 1, usually 1/2


Drawing Types


Ideas are captured in a visual format using symbols, words, lines, etc.


Tree diagrams

Flow chart

Represents an algorithm or process

Flow chart: Freehand

Venn diagrams

Show all possible logical relations between a finite collection of sets

Paul Bennett IDEO

Click me

Engineering Diagrams

Statics: Free Body Diagrams


Controls: Block Diagrams

Materials: Lattice Diagrams

Fluids: Flow Diagrams

Fluids: Hydraulic Diagrams

Thermodynamics: Sankey Diagrams

Famous Sankey Diagram


Exploded View