AXONOMETRIC PROJECTION
Axonometric projection is a type of orthographic
projection used for creating a pictorial drawing of an object,
where the lines of sight are perpendicular to the plane of
projection, and the object is rotated around one or more of its
axes to reveal multiple sides.
"Axonometry" means "to measure along axes".
axonometric projection encompasses every type of parallel
projection, including not only oblique projection, but
also orthographic projection and therefore multiview projection.
A multiview projection depicts an object from one of six primary
views (e.g. front, right, left, top, bottom, or back); when being
projected, one of the principal axes of the object (e.g. the z or
"depth" axis) is necessarily perpendicular to the projection
plane, and thus such a projection can depict only one "side" of
the object.
an axonometric projection may depict an object such
that none of the principal axes of the object is perpendicular to
the projection plane, and thus more than one "side" of an object
may be represented simultaneously (that is to say, the z or
"depth" axis may be represented); usually, the projection is
such that the images of any 2 axes are not collinear, so that the
angles between projected lines help to distinguish each
dimension.
The three types of axonometric projection are isometric
projection, dimetric projection, and trimetric projection,
depending on the exact angle at which the view deviates from
the orthogonal. Typically in axonometric drawing, as in other
types of pictorials, one axis of space is shown as the vertical.
In isometric projection, the most commonly used form of
axonometric projection in engineering drawing, the direction of
viewing is such that the three axes of space appear
equally foreshortened, and there is a common angle of 120°
between them.
In dimetric projection, the direction of viewing is such that two
of the three axes of space appear equally foreshortened,
In trimetric projection, the direction of viewing is such that all
of the three axes of space appear unequally foreshortened
.
Isometric projection is a type of pictorial projection in which the
three dimensions of a solid are not only shown in one view, but their
actual sizes can be measured directly from it.
If a cube is placed on one of its corners on the ground with a solid
diagonal perpendicular to the V.P., the front view is the isometric
projection of the cube.
The three lines CB, CD and CG meeting at the point C and making
120° angles with each other are termed isometric axes. The lines
parallel to these axes are called isometric lines. The planes
representing the faces of the cube as well as other planes parallel to
these planes are called isometric planes.
Isometric projection is a method for visually representing
three-dimensional objects in two dimensions
in technical and engineering drawings. It is an axonometric
projection in which the three coordinate axes appear equally
foreshortened and the angle between any two of them is 120
degrees.
The term "isometric" comes from the Greek for "equal
measure", reflecting that the scale along each axis of the
projection is the same (unlike some other forms of graphical
projection).