Elevation II
A building elevation is a wall with holes in it. The type, proportion, and rhythm of those holes tells you what the building is before you read a single label. Four building types, all generated at once.
Elevation I made one rule for a single kitchen wall: every height has to say what it is measured from. This post takes that rule outside, to the whole face of a building, and adds the direction Elevation I never had to deal with: sideways. Every hole in these four walls is two numbers, a sill measured up from grade and an offset measured from the left corner. The question is whether those two numbers are enough to make a building read as what it is, and what happens to the parts of the reading they don’t store.
Purpose: show that building type is encoded in the elevation. Storefront glazing reads commercial. Punched windows read residential. You can't confuse them.
What the drawing holds
The drawing builds the four walls from the original applet’s own tables, one element at a time as the text goes, all at one scale: residential and civic stand on one grade line, commercial and industrial on another, and each row’s datum lines run straight across both walls. The cards report the wall under discussion: its opening share (open area divided by wall area), the wall left above its highest head and how many of its openings are mirrored about the wall’s centerline, the dash-dot line in each wall. At the end all four stand side by side.
| Facade | Wall | Openings | Open area | Opening share | Highest head | Mirrored about centerline |
|---|---|---|---|---|---|---|
| Residential | 36′ × 12′ | One 3′ × 6.8′ door, four 3′ × 4′ windows | 68.4 sf | 15.8% | 6.8′ | 0 of 5 |
| Commercial | 40′ × 14′ | Four 8′ × 9′ storefronts, one door | 308.4 sf | 55.1% | 9′ | 0 of 5 |
| Industrial | 48′ × 16′ | Three 9′ × 7′ overhead doors, one door, one window | 221.4 sf | 28.8% | 7′ | 0 of 5 |
| Civic | 44′ × 18′ | One 5′ × 7′ double door, two 6′ × 4′ windows, two 3′ × 4′ windows | 107 sf | 13.5% | 7′ | 3 of 5 |
“Explicit” here means a number in the applet’s tables: the four wall sizes, the six opening sizes, the sills (2.5 feet for windows, grade for everything else) and each opening’s left-edge offset. The original only ever drew one of those numbers on screen, the overall width dimension over each wall; the rest lived in the code. Everything else on this page is inferred, arithmetic I am doing on those numbers: the head heights (sill plus height), the centerline, the mirror count. The type names are the applet’s visual examples, not occupancy classifications. One explicit number has been changed, the industrial window, and it gets its own section below.
What actually tells you the type
Opening share does most of the work. The commercial wall is 55.1% hole, three and a half times the residential 15.8%: storefront glazing reads commercial, exactly as the purpose line says. Industrial lands in between at 28.8%, but its holes are 9-foot-wide overhead doors starting at grade, 63 square feet each, and nothing else on these walls comes close to that size.
Share alone does confuse two of them, though. Residential is 15.8% open and civic is 13.5%, a 2.3-point difference nobody would see. What separates them is the wall above the openings. The residential wall is 12 feet tall with its highest head at 6.8, which leaves 5.2 feet of wall on top. The civic wall is 18 feet tall and nothing on it opens above 7, so 11 feet of solid wall sits over every opening. Commercial keeps 5 feet over its 9-foot storefronts; industrial keeps 9 over its doors. “Monumental” in this applet turns out to mean a tall blank wall and a centered double door. The holes themselves are nearly residential.
The heads deserve one more look. On the residential wall the windows top out at 6.5 feet (a 2.5-foot sill plus 4 feet of window) and the door tops out at 6.8, so the window heads stop about 3.6 inches short of the door head. Nothing in the table relates the two; they are two sums that happen to differ. Whether they should line up is a design decision, and the table can’t ask it.
What the holes measure from
Vertically, the answer is easy. Every sill is measured up from grade, at 0 or 2.5 feet. That is Elevation I’s FFE under another name. Horizontally, every opening is measured from the left corner and from nothing else, and that is where the labels start to drift from the numbers.
The original applet described the residential wall as a “symmetrical window rhythm.” Its four windows sit at 8, 14, 22 and 28 feet, 3 feet wide each. They are symmetric, about 19.5 feet: (8 + 31) ÷ 2 = (14 + 25) ÷ 2 = 19.5. The wall’s centerline is at 18. So the window group is 1.5 feet off center, and the mirror card reads 0 of 5. That may well be deliberate, nudging the group away from the door at 2 to 5 feet. The table can’t tell you, because it stores where the windows ended up, not what they were lined up on.
It described the civic wall as “formal symmetry.” The double door, 19.5 to 24.5 feet, is centered on the 22-foot centerline, and the two wide windows at 2 and 36 mirror each other exactly. The two small windows at 14 and 28 don’t: the mirror of a 3-foot window starting at 14 starts at 27, not 28. Three of five openings are symmetric, and the card says 3 of 5. A one-foot miss on the most formal wall in the set is the kind of error that survives every view until somebody stands in front of the building.
Commercial and industrial never claimed symmetry, and the mirror card reads 0 of 5 for both. The commercial run is a true rhythm: four 8-foot storefronts on 9-foot centers with 1-foot piers between them, then a 3-foot door that ends flush with the right corner, with no pier at all. Even there the rhythm is not stored as a rule. It is five offsets that happen to step by 9.
The one number this study changed
In the original applet the industrial service door sat at 40 feet and its window at 38. A 3-foot window from 38 to 41 and a 3-foot door from 40 to 43 share a foot of width, and the window’s band from 2.5 to 6.5 feet sits inside the door’s 0 to 6.8. That is a 1′ × 4′ overlap, 4 square feet of window cut into a door. The original canvas cleared both rectangles and drew it anyway. This study moves the window to 36 feet, which leaves a foot of wall between it and the door, and draws the original position as a dashed outline. With the window moved, the industrial wall has 221.4 square feet of openings; at 38, counted once, it would have had 217.4, or 28.3%.
So the same failure shows up three times: windows off center on the residential wall, a pair off by a foot on the civic one, a window inside a door on the industrial one. Every opening was placed on its own from the corner, and the relationship the label promised (symmetric, paired, beside the door) never became a number. Elevation I’s rule for heights holds sideways too. The coordinate is the easy part. The parent is the design decision.
A change the drawing can’t make yet
The applet has no width control, so this one is arithmetic on its numbers, not a preset. Widen the civic wall from 44 to 48 feet and leave the table alone. The centerline moves to 24. The double door, still at 19.5 to 24.5, is now centered at 22, two feet left of the middle. The wide windows at 2 and 36 used to mirror each other; on a 48-foot wall the mirror of the left one runs from 40 to 46, so the right one is now 4 feet short of where it should be. Mirrored count: 0 of 5. Not one number in the table changed, and the formal symmetry is gone. Store the door as “centered on the wall” and the wide windows as “2 feet in from each end,” and the same widening keeps all three where they belong.
The judgment
The purpose line said you can’t confuse these, and in the numbers you mostly can’t: the share of the wall that is hole, and how much wall sits above the highest head, separate all four. But the qualities the labels are proudest of, symmetry, pairing and rhythm, aren’t stored anywhere. They are coincidences of five left-edge offsets, and coincidences break the first time the wall changes size. A facade generator should store each opening the way Elevation I stores a cabinet: a sill hosted on grade and a horizontal parent, whether that is the centerline, a bay, an end of the wall or the room behind it. Then “symmetric” is a rule the generator keeps instead of a caption somebody writes under the drawing.
The parent I would pick is the room behind the wall, and the room is where this series goes next. Every drawing so far has been a view of something already decided: a sheet that has to fit a building, a cabinet that has to hang from a ceiling, a facade that has to read as a type. The deciding happens in the room, so the second half of the series stops placing views and starts writing down what a room has to hold.