tianjara.net | Andrew Harvey's Blog

I discovered this back in 2007 when I was preparing for my HSC exams.

Here is the question (from the exam paper here),

[caption id="attachment_310" align="aligncenter" width="450" caption="2001 HSC ITG Q5a"][/caption]

Firstly I think this question is beyond the scope of the syllabus. The only relevant dot point says,

"Pictorial drawing

• isometric
• perspective (mechanical and measuring point)"

There is no reference to oblique drawing or oblique projection (this was the official answer).

Secondly, and more importantly the examiners say in their Notes from the Marking Centre, "This part was generally well answered; candidates had little trouble in identifying oblique and perspective projection."

They claim that the first one is oblique projection, yet with just the information given its impossible to determine the projection used. For example the drawing given could be of a cube drawn in oblique projection or it could be of another object (shown below) in isometric projection, or some other object in some other projection. There are infinity different projections that it could have been drawn in.

[caption id="attachment_311" align="aligncenter" width="450" caption="An object (I call a Vube) shown in 3rd angle orthogonal which when drawn in isometric looks like a cube in oblique."][/caption]

[caption id="attachment_312" align="aligncenter" width="450" caption="Vube shown in perspective."][/caption]

The exam paper should have specified that the object in question is a cube.