Isometric projection is one of the three forms of axonometric projection. In isometric projection the angles between the projection of the axes are equal i.e. 120[$ordm]. It is important to appreciate that it is the angles between the projection of the axes that are being discussed and not the true angles between the axes themselves which is always 90[$ordm].
In trimetric projection the projection of the three angles between the axes are unequal. Thus, three separate scales are needed to generate a trimetric projection of an object. The scales are constructed using the same method described in isometric and dimetric projection. An example below shows the method of construction for each of the scales.