Point in Monge projection

SŠ9 min

Folding simulator: watch π₁ rotate about x₁₂ to form the drawing.

○Not Started
x₁₂AA₂A₁π₁π₂
0°3D space

Fold the planes

Point A

[1.6, 3.0, 2.4]

Quadrant: 1

Drag the fold angle. π₁ rotates about the ground line x₁₂ and the top view A₁ lands below the front view A₂ – the classical Monge drawing.
2

Theory

A point in space is fixed by three coordinates [x, y, z]. In Monge projection we represent it with two views: the front view A₂ on the vertical plane π₂ and the top view A₁ on the horizontal plane π₁.

To draw both views on one sheet we fold π₁ about the ground line x₁₂ into the plane π₂. This drops the top view below the ground line.

Both views lie on a single vertical ordinate – the x-coordinate is shared. That is a property to understand, not memorize.

3

Step-by-step construction

3D – what happens in space
x₁₂π₁π₂
Drawing – what you draw
x₁₂π₂π₁
1 / 5
4

Practice

Build the construction yourself

3D – what you have
x₁₂π₁π₂
Your drawing
x₁₂π₂π₁

What is the next step?

1 / 4

Choose the step that comes next. The drawing only advances on a correct choice.

Check your understanding

1

Where is the front view A₂ of a point above π₁?

2

What links A₁ and A₂ in the finished drawing?

3

About what do we fold π₁?

5

Downloadable material

A PDF for this lesson is in preparation.

Need help?

Book a lesson and we will go through it together, step by step.

Book a lesson