camera obscura
set up along a corridor somewhat [30 ft from one end, 60 ft from another] the perspective is drawn of one view, then a turn back and the perspective drawn over the first one. taking the true height of the floor to ceiling in the place i stand-this is the measurement from which i start.
to pull down the plan from the perspective is next and the overlap of the two drawings is collected, then the "residual" or leftover spaces are collected. the openings for door and window are pulled, and then rotated 180 degrees to meet with the others, and then a showing of the extrusion into other spaces.