Isometric projection is a viewing direction. It is the 3D representation of an object where the object appears to be rotated at 30 degrees. It is commonly how questions and tasks may be presented to you because of their true and descriptive appearance.
Types of isometric Projection
Students have the option when answering these task whether to use the Axonometric method (top) or the 'crows foot' isometric scale method (bottom) of drawing the object.
Axonometric Projection: The Axonometric method uses an equilateral triangle and the necessary orthographic views to complete the drawing. The method is demonstrated in the image below and in detail in the slides at the bottom of this page.
The Figure shown shows the incomplete isometric. The circle detail has not been included for clarity. Please see slides at the bottom of the page for details on the circle.
As you can see, we position the relevant orthographic and project them back into the center. The corresponding intersecting lines become points/lines on our isometric drawing. This method is also used on other types of views called Dimetric and Trimetric. These use the same principles with different variations of the center triangle. However, they are studied in Senior Cycle DCG.
'Crows Foot' Isometric Scale Method: This method starts with one edge/imaginary edge and projects back from it. In the case of the figure you saw above, it is the very front edge that you can see. This method for the most part, doesn't concern itself with orthographic views. It works primarily off dimensions. It gets its name 'crows foot' from the guiding axis lines drawn at the beginning of the question seen on the left below. The lengths, widths, heights and other dimensions are primarily applied along or parallel to these axes.
The figure shown is the 'crows foot' setup (left) and the isometric Scale (right).
The isometric scale (image on the right above) must be applied to a task completed at higher level. each dimension given in the question must be applied along the true length 45 degree line and transferred to the isometric line at 30 degrees. We then use the isometric length.
Requirements for Examination
Axonometric (Higher Level): - Correctly Setup the procedure. - Correctly position the relevant Orthographic Views. - Transfer the orthographic views to the center to create an isometric view by creating points with intersecting lines. - Draw slanted surfaces. - Draw Curves.
OR
Isometric Scale: - Apply correct dimensions along the axes. - Draw slanted surfaces. - Draw Curves (Higher Level). - Apply the Isometric Scale (Higher Level).
Ordinary level are given the option to complete the task using Oblique Projection. I strongly recommend this oblique option as it is far less complex and time consuming.
PowerPoint File
Click on the download link below to download my PowerPoint slides on isometric projection.