Q1.
Notice that this only shows the map of the floor. Do you see why the position of the windows cannot be marked on this map?
Answer
Because Fig. 1.1 is a map of the floor only, and a window is not on the floor.
A point on the floor needs two numbers: how far along the room, how far across.
A window needs a third number as well: how high up the wall it is.
A window needs a third number as well: how high up the wall it is.
Why it happens: Shalini’s grid of pins is a flat, two-dimensional model. Fixing two axes on the floor fixes exactly two independent directions — along the room and across it. Every point of the floor gets one address (x, y), and that address is complete. Height is a direction perpendicular to both axes, so no pair (x, y) can record it. On the floor plan a window would collapse onto the wall line and be indistinguishable from the wall itself.
The doors can be marked, because a doorway is a gap that reaches down to the floor. It leaves a real gap in the wall line of the plan. A window leaves no gap at floor level.
Tip: To record windows you would need a third axis (height) — that is 3-D coordinates (x, y, z). Architects get around this by drawing a separate elevation: a second 2-D drawing whose two axes are “along the wall” and “height”. Two flat drawings together carry the three-dimensional information.
Check it yourself: Reiaan can feel the wool along the bottom wall and find the door gap with his fingers. Ask yourself what he would feel where a window is — an unbroken thread, exactly like the rest of the wall.