trimetric

Trimetric refers to a type of axonometric projection used in technical drawing and graphics in which the three coordinate axes are foreshortened by three unequal amounts. In a trimetric projection, the angles between the projected axes are not equal and the scale factors along the x, y, and z directions are all different. This contrasts with isometric projection, where all three axes are equally foreshortened, and with dimetric projection, where two axes share the same scale.

In practice, trimetric projection is an orthographic (parallel) projection. The object is rotated and then projected onto a plane with three independent foreshortening factors, often denoted as (s_x, s_y, s_z). Because the scales differ, lines parallel to each axis remain parallel in the drawing, but the appearance of length and angle varies more irregularly than in isometric or dimetric views. The resulting image can be tailored to emphasize certain features or to provide a more natural look for specific objects.

Historically, trimetric views were one of the standard axonometric options in engineering and architectural drawing, offered as an alternative to isometric representations. In modern practice, trimetric projections are still supported by many CAD and 3D software packages, where users can specify three independent axis scales or use a custom projection matrix. While less uniform than isometric or dimetric views, trimetric can deliver a clearer depiction of form for certain objects.

See also: axonometric projection, isometric projection, dimetric projection, technical drawing.