TALAMANA · THE AI LITERACY MAP FOR ARCHITECTURE AND DESIGN · Foundations · AGE 15—17 · FACTUAL · DURABLE
A picture of a plan is not a plan
A generated plan is a grid of colours and cannot be measured.
The idea
A plan can be stored three ways. A raster image — a JPEG, a PNG, a screenshot — is a grid of tiny coloured squares: no lines, no lengths, only colours in positions. A CAD drawing is vector: each line is stored as geometry, with a start, an end and a length, so it can be measured. A BIM model stores a wall as an object that knows it is a wall, with thickness, material and openings. An image generator makes the first kind only. A generated plan cannot be measured: a raster has nowhere to keep a length.
Why it matters
Once you know which of the three kinds a file is, you know what can be asked of it. You can ask a raster what it looks like. You can ask a vector what it measures. You can ask a BIM object what it is.
See it in the studio
A client sends a photograph of a plan on WhatsApp and asks you to "just pull the dimensions". You cannot. The photo has pixels where the drawing had lines. You redraw it, and you measure the real room to check, because the pixels never held the number. A generated plan is that photograph, with no original behind it.
Watch for this
A generated image that looks like a drawing. Clean black lines on white, a north arrow, a scale bar. Every one of those is painted. The scale bar is a picture of a scale bar. Nothing in the file is 1:100.
Try it
Draw a small room in any CAD tool: four walls, one door. Export it three ways — as a DWG or DXF, as a PDF, and as a PNG screenshot. Open each and try to measure the door. Then, in the CAD file, select one wall and list what the software knows about it. If your college has a BIM tool, do the same with a wall there and compare the two lists.
Prove it
Explain the difference between a raster image, a vector drawing and a BIM object using one wall, and say which of the three a generated image is.
How it works
A raster stores colour values in a grid; zoom in and the squares show. A vector format stores drawing commands — lines, arcs, shapes — as numbers in real units, so the same file renders sharp at any size. A BIM model stores building elements as objects with properties and relationships. In the open IFC standard, for instance, a wall is an IfcWall: a vertical construction that may bound or subdivide spaces, with its openings attached to it as objects of their own. Today's image generators work in pixels: diffusion models, and most other image generators in wide use, produce a grid of colour values, and DIFFUSION on the Generative Mechanics strand shows how. A model can be asked to draw something that resembles a plan, and with a control input it can be held close to a plan you supply, but the output file is still a raster. The machine does not lack a ruler so much as a place to keep a length. Turning a raster back into geometry — vectorising a scan, reading a plan from a photograph — is a separate task, and current benchmarks find models well behind people at it. NO RULER, READ A PLAN and BIM MEETS AI on this map each start from this card.
What this idea builds on
What this idea opens up
Sources
Open this idea on the map · The complete map · Logika · RBDS AI Lab, India · revised every edition.