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Isometric & Orthographic Projections - Coggle Diagram
Isometric & Orthographic Projections
Isometric Projection
Isometric means equal measure. Therefore to produce an isometric drawing, the principal edges are equally inclined to the viewer and they are of the true length. Isometric drawings are constructed on 3 axes that divide the circle equally. They are 120° from each other.
Orthographic Projections
A simple way of representing engineering design drawings is by using orthographic projections. Orthographic projections are a collection of 2D drawings used to define a 3D model.
There are six possible views: Front, Back, Top, Bottom, Left, Right.
Usually, Front + Top + Right gives a complete view.
Back, Bottom, and Left views can often be skipped as they mirror the opposite sides.
If the Bottom view has more detail, we can use Front + Bottom + Right instead.
First and Third Angle Projections
First Angle: Object is between observer and projection plane; views are projected on the opposite side.
Third Angle: Projection plane is between observer and object; views are projected on the same side.
These methods are key for reading and creating technical drawings.
First Angle is commonly used in European countries.
The orthographic projections are on the opposite side.
Third Angle Projection is commonly used in U.S.
The orthographic projections are on the same side.
Types of Lines in Orthographic Drawings
Visible lines show parts of an object that can be seen in a view.
They are solid, thick lines that clearly outline the object's shape and details in engineering drawings.
Hidden lines show parts of an object not visible in a view.
They are drawn as dashed lines and reveal internal or hidden features essential for understanding the full structure.
Center lines mark the centers of holes, cylinders, and symmetrical features.
They are drawn with long and short dashes and help with accurate positioning and alignment.