Something I've never understood about 2D/Flatland as a "visual" idea: In the case of this Mar1d, if I'm on the X-axis, and can only see the Y-axis, wouldn't any amount of detail in the Z-axis constitute a 3D image? The Y-axis stretched even a single "pixel" along Z would make it 3D, right? Similarly, for Flatlandia: If I'm a 2D square on the X-axis, and can see "around" me on the Z-axis, wouldn't my ability to see an…
When we're rendering a 3D environment on a 2D plane, we're projecting it "down", so that we can perceive it.
When we're rendering a 2D environment on a 2D plane, are we doing nothing to to ? Maybe, but the 2D environment we've constructed to begin with is probably inspired from our native 3D thinking.
But when we're rendering a 1D environment on a 2D plane, which we need to do to perceive it, because we don't have a visual organ for perceiving 1D environments of the kinds constructed in "native 2D thinking".. So we're projecting "up", adding data to convey a representation of the environment that we can perceive, not as it "is".