The variable third dimension

The variable third dimension 

I've been rereading Gibson's The ecological approach to visual perception, enjoying his relentless debunking of many things we accept unquestioningly, mainly because everybody accepts, believes and propagates them. I've grown rather wary of statements that include "of course", especially if people listen to them and just nod in acceptance. Automatically I make a mental note to examine them more critically.
One of the concepts Gibson attacks with conviction is the third dimension in visual perception. He suggests that thinking of depth as the third dimension comes from erroneously believing that what we perceive is a two-dimensional projection, just like in a camera. He points out how unnatural it is to analyse visual perception with such projections, while in reality we constantly change our viewpoint by moving our heads and bodies. One could therefore say that once again metaphors and implementation mechanisms distort our thinking and cloud our understanding.
In architecture the third dimension is different: not depth but height. The difference actually stresses the similarity of both cases: both start from a two-dimensional projection as the reality. The floor plan is one of my favourite representations, a marvel of overview and economy. However, any design described by a floor plan is three dimensional. What the floor plan describes is just some aspects of the design. The rest should be in the designer's mind or other, complementary representations.
That's why I feel inclined to roll my eyes every time someone claims that this or that adds the third dimension to drawings or designs, that it liberates architecture from two-dimensional tyrannies. Such claims merely reveal fundamental misconceptions and lack of understanding of one's tools. That's the real tyrannies.