Isometric: Isometric Drawing and its characteristic

Posted by Sudarshantech on February 17th, 2020

It is one of the forms of projection used in technical drawing like REVIT MEP Design that has the advantage of allowing scale representation. Isometric determines a visualization direction in which the projection of the coordinate axes x, y, z make up the same angle, that is, 120º from each other. The objects are shown with a rotation of the viewpoint of 45º in the three main directions (x, y, and z).

This perspective can be visualized considering the point of view located at the top vertex of a cubic room, facing the opposite vertex. The x and y axes are the straight lines of the encounter with the floor, and the z axis, the vertical, the encounter of the walls. In the drawing, the axes (and their parallel lines), maintain 120º between them.


Within the set of axonometric or cylindrical projections, there are other types of perspective. Which differ by the position of the main axes, and the use of different reduction coefficients to compensate for visual distortions.

Isometric Drawing:

Isometric refers to that three-dimensional drawing that has been made with the inclined axes forming an angle of 30 ° with the horizontal.  One of the great advantages of P&ID Diagram is that the drawing of any model can be made   without using any special scale, since the lines parallel to the axes are taken in their true magnitude. Thus, for example, when the cube is drawn in an isometric way, it has all its edges of equal measure.

A widely used variety of the Isometric Perspective is the Isometric Drawing. In the Isometric one the coefficient of reduction of the dimensions equivalent to approximately 0.816, that is to say, along the axes a real dimension 1 is multiplied by that factor. Being the identical reduction in the three axes, the isometric drawing is made without reduction, with the dimensions parallel to the axes at 1: 1 scale or natural scale. Without changing the appearance of the drawing except in its size.

This allows both to draw these dimensions directly on paper (which facilitates drawing by Cartesian coordinates and directly measuring those of an object in the drawing. The appearance of the drawing is identical although larger, and the dimensions that in the correct perspective would be equal to the real ones (those parallel to the projection plane) are larger. The scale on which the Isometric Drawing is larger compared to the Isometric Perspective is approximately 1.22.

Characteristics of the Isometric Drawing:

An isometric drawing is not an isometric viewpoint, since it is done without any reduction. This, like the isometric perspective, reveals the faces of the solid in the three sectors of the axes, with the same amplitude. We can also make Structural Steel Detailing with isometric drawing.

Axes used in the Isometric Drawing: The basis of the isometric drawing is a   three-axis system called "isometric axes" that represent the three edges of a cube, which form 120 ° angles

 Isometric Lines: Are those lines that are parallel to any of the three isometric axes

Non-Isometric Lines: They are those inclined lines on which true distances cannot be measured. When these lines are present in an isometric drawing, they are neither along the axes nor parallel to them.

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