# What's Inside an AI-Generated DXF: Layers, Sheets, Limits **The DXF Nuit exports from a generated 3D model is one file with seven views in model space, on 24 declared AIA-style layers mapped from each element's IFC class, with a plan cut at 1.2 m, overall and wall-axis dimension chains drawn as lines and text, room outlines labelled with name and area, and library assets as silhouettes. It contains only polylines, lines and text: no blocks, no hatches, no layouts, no associative dimensions, no hidden-line removal. It is a concept-stage set whose seven views agree with each other exactly, and it is not a substitute for the drawing an office produces once the design is settled.** This article is the file specification in plain language, written so that an architect can decide in five minutes whether the export is worth opening. Everything below is read from the exporter's source and from the published Mirror Lake House file on the [examples page](/3d/examples/); where we cite a number, it is a number from that file. --- ## One file, seven views The export writes all views into a single DXF rather than a zip of seven. They sit in model space in a row, left to right, three metres apart, each with a text label above it: ``` PLAN ELEVATION NORTH ELEVATION SOUTH ELEVATION EAST ELEVATION WEST SECTION X SECTION Z ``` An empty view (a section that cuts nothing) is skipped rather than reserved. Each view is a flat 2D projection in the drawing's XY plane; the file has no 3D entities. Why one file: it is what an architect opens first for a check, and it avoids a dependency for zipping in the exporter. If you want a single view, the studio's export panel can write just the plan, one elevation or one section, with its own settings. **Units.** Millimetres by default (`$INSUNITS` = 4), or metres on request. All coordinates are scaled accordingly; the text on dimensions says which. **Plan cut height.** 1.2 m by default, the conventional height that catches windows and door openings. It can be set to any level, which is currently how a first-floor plan is obtained, since the export writes one storey. **Sections.** Through the model origin on X and on Z. The single-view export accepts any position along either axis. --- ## The layer table Every element in the model carries the IFC class it was tagged with when the script built it. The DXF exporter maps that class to a layer name in the style of the AIA CAD Layer Guidelines: not the whole standard, only the discipline codes a villa plan, section and elevation need. | Layer | Contents | ACI colour | |---|---|---| | A-WALL | Walls (IfcWall) | 1 red | | A-FLOR | Slabs (IfcSlab) | 3 green | | A-ROOF | Roof elements (IfcRoof) | 5 blue | | A-GLAZ | Windows (IfcWindow) | 4 cyan | | A-GLAZ-CWMG | Curtain walling (IfcCurtainWall) | 4 cyan | | A-DOOR | Doors (IfcDoor) | 6 magenta | | A-STRS | Stairs and flights | 1 red | | A-RAIL | Railings, balustrades, glass guards | 6 magenta | | A-FNSH | Coverings: cladding boards, floor and ceiling finishes | 8 grey | | S-COLS | Columns | 2 yellow | | S-BEAM | Beams, rafters, ridge, joists, standing-seam ribs | 30 orange | | S-MEMB | Members and plates: frames, mullions, base plates | 30 orange | | S-FNDN | Footings | 9 grey | | P-PIPE | Pipes, gutters, ducts | 30 orange | | P-FIXT | Sanitary fixtures (asset silhouettes) | 4 cyan | | I-FURN | Furniture (asset silhouettes) | 8 grey | | E-LITE | Light fittings (asset silhouettes) | 2 yellow | | L-PLNT | Planting and site features (asset silhouettes) | 3 green | | C-TOPO | Site: ground, water, banks | 9 grey, dashed | | A-AREA | Room outlines (IfcSpace) | 9 grey, dashed | | A-MISC-BLW | Projection of geometry below the plan cut | 9 grey, dashed | | A-MISC | Anything without a recognised class | 8 grey | | A-ANNO-DIMS | Dimension lines and values | 7 white/black | | A-ANNO-TEXT | View labels, room names and areas | 7 white/black | All 24 layers are declared in the file's table whether or not a given view uses them, so a plan without glazing still has an A-GLAZ layer to turn on. The Mirror Lake House export uses 19 of the 24 across its seven views; Marlow Boathouse uses 18. The most populated layers in Mirror Lake are A-FNSH (cladding boards), S-BEAM and S-MEMB, which is the honest signature of a standing-seam roof on a timber-clad house. If you prefer your own layer standard, the mapping is a rename: one class, one layer, no exceptions. --- ## How each view is constructed **Plan.** A horizontal cut through every element at the cut height. Elements the plane passes through produce closed outlines on their class layer (a wall becomes its two faces and end caps as a polyline). Geometry below the cut plane, the floor slab, the deck, the footings, is projected as dashed outlines on A-MISC-BLW so that the plan reads as a plan and not as a section of a floor. Each IfcSpace is drawn as a dashed outline on A-AREA, with its name and floor area ("Main bedroom - 13.9 m2") as text on A-ANNO-TEXT at its centre; the areas are the same NetFloorArea quantities the IFC carries. **Elevations.** An orthographic projection of visible edges from each of the four sides: the silhouette plus every edge whose dihedral angle exceeds 30°. Hidden lines are **not** removed. A column behind a wall is drawn through the wall; a bed behind a window appears in the elevation. This is a known simplification of the exporter, stated in its source, because true hidden-line removal is a rasterisation or boolean problem of a different scale. For a concept elevation it is usually acceptable, and where it is not, freezing I-FURN, L-PLNT and A-FNSH removes most of the noise. **Sections.** The same cut logic as the plan, on a vertical plane, and only the cut: elements beyond the plane are not projected, so a section shows the sliced walls, slab, roof and structure and not the far wall's windows. Cut elements produce closed outlines on their class layer; a library asset the plane passes through is drawn as one silhouette rather than a scatter of cut triangles. Expect the sections to read sparser than a hand-drawn one until you add the elevation beyond. **Dimensions.** Drawn on A-ANNO-DIMS as primitives: two extension lines, a dimension line, tick marks, and a text value at the midpoint. On the plan there are two kinds of chain per axis: an overall dimension outside the outline (along the bottom for X, along the left for Z) and a chain across the wall axes between the outline and the overall. Wall axes are read from the same tag the IFC uses (`extrude.axis`), so a wall is dimensioned to its centreline. On elevations and sections, level marks at 0.00 and at the top of each element's bounding box. The Mirror Lake file has 72 entities on A-ANNO-DIMS. The dimension numbers are computed by the same function that draws the dimension overlay in the studio's plan view, from the same bounds, which is why the screen and the file never disagree. **Library assets.** Trees, shrubs, furniture, lamps and sanitary ware placed from the asset catalogue are drawn as one closed polyline per instance: a convex hull of the projected vertices of every mesh in the instance, crown and trunk merged. The reason is arithmetic: the 24 pines on the Mirror Lake site are 27,000 triangles each, and drawing every asset edge by edge produced about 930,000 polylines across the seven views and a 232 MB file. With silhouettes, the published file has 3,239 polylines in total and is 1.6 MB. The export panel offers three modes: outline (default), full, or none. --- ## What is in the file, by entity Reading the Mirror Lake House DXF as data: - **LWPOLYLINE**: 3,239. Every outline, cut, edge chain and silhouette. - **LINE**: 52. Dimension lines and level marks. - **TEXT**: 32. Dimension values, room labels, view labels. - **LAYER**: 24. The table above. - Header, two line types (CONTINUOUS, DASHED), one text style. That is the whole file. No INSERT or BLOCK, so every door is drawn geometry rather than a block instance. No HATCH, so cut walls are outlines, not poche. No MTEXT, no DIMENSION, no LAYOUT or paper space, no title block, no viewports, no xrefs. Nothing is 3D. The exporter was written with this restraint on purpose: a small, predictable subset of DXF that every CAD program opens identically, rather than a richer file that opens differently in each. The trade is described in the exporter's own comments as "simpler and more reliable over completeness of format". --- ## Compared with a hand-drawn concept set This is the comparison an office actually cares about. Take a schematic set that a competent architect draws in AutoCAD for a small house at concept stage, and put it next to the export. **The hand-drawn set has, and the DXF does not:** - Door and window blocks with swings, tags and a schedule. - Hatching of cut material, and line weights that distinguish cut from projected beyond colour. - A title block, sheet numbers, north point, scale bar; paper-space layouts at a scale. - Associative dimensions in the office style, with opening dimensions and setting-out where needed. - Hidden-line removal on elevations, and the elevation of what lies beyond a section plane; the judgement about what not to draw. - Multiple storeys as separate plans, and a roof plan. - Annotations: materials, levels, notes, room numbers in the office scheme. **The DXF has, and the hand-drawn concept set often does not:** - Seven views that agree with each other exactly, because they are projections of one model rather than seven drawings. A window that moves in the model moves in the plan, both elevations that see it and any section that cuts it, and the dimension chain updates on re-export. - Room areas that are computed, not estimated. - A model behind it that can be re-exported in an hour after a change, rather than redrawn. - Wall-axis dimensions that were never rounded by hand. **What neither has:** anything that requires a decision the concept did not make. Wall build-ups, fire ratings, drainage falls, the structural engineer's sizes. Both are concept drawings. Only one of them was drawn. The right use of the DXF, then, is as the base for the hand-drawn set, not its replacement. Open it, copy the plan into your template, replace outlines with your wall types and blocks, dimension in your style, hatch, lay out. What you skipped is the part where someone measures a render with a scale rule. [AutoCAD + AI: What Actually Works](/blog/autocad-ai-2026/) walks through that opening sequence; [From AI Concept to Construction Drawings](/blog/from-ai-concept-to-construction-drawings/) covers the phases that follow. --- ## What not to expect Being explicit, because search engines will quote this section out of context: - **No dimension chains beyond overall and axis**, and none that are associative. - **No schedules, specifications or quantities in the DXF.** Quantities are in the IFC4 export of the same model ([AI to Revit](/blog/revit-ai-ifc-concept-to-bim/)). - **No blocks, hatches, layouts or title blocks.** - **No hidden-line removal** on elevations, and **no projection beyond the cut** in sections. - **One storey per export**; other levels by changing the plan cut height. - **No DWG.** DXF only; AutoCAD saves it as DWG in one step. - **No import.** The DXF comes from the model; nothing goes back in. - **Concept-stage geometry.** The model has walls, partitions, openings, slab, roof, structure, rooms and site; it does not have joinery, services or details, so neither does the drawing. --- ## Trying it Download `mirror-lake-house.dxf` from the [examples page](/3d/examples/), open it in AutoCAD, BricsCAD, Archicad or any CAD that reads DXF, and open the Layer Properties Manager first. The layer table is the quickest way to see whether the classification matches how your office draws. Then look at the plan's dimension chains against the room labels; 20 × 6 m, five rooms, 110.4 m². If the file is useful as a base, the [model that made it](/3d/) is open to every account from the Images | 3D switch in the studio. If it is not, you have lost five minutes and gained a specification. For how the model gets made, [From an AI Floor Plan to a 3D Model](/blog/ai-floor-plan-to-3d-model/); for the SketchUp and Blender route, [SketchUp + AI](/blog/sketchup-ai-alternatives-2026/). --- ## Frequently Asked Questions ### What views are in the DXF? Seven in one model-space file, side by side with a text label each: PLAN, four ELEVATIONs, SECTION X and SECTION Z. Plan cut at 1.2 m by default and adjustable; sections through the origin. A single view can be exported alone. ### What layers does the DXF use? AIA-style names from each element's IFC class: A-WALL, A-FLOR, A-ROOF, A-GLAZ, A-GLAZ-CWMG, A-DOOR, A-STRS, A-RAIL, A-FNSH, S-COLS, S-BEAM, S-MEMB, S-FNDN, P-PIPE, P-FIXT, I-FURN, E-LITE, L-PLNT, C-TOPO, plus A-AREA, A-ANNO-DIMS, A-ANNO-TEXT, A-MISC-BLW and A-MISC. 24 declared; Mirror Lake House uses 19. ### Are the dimensions real AutoCAD dimensions? No. Lines and text on A-ANNO-DIMS, exact but not associative and without a dimension style. Re-dimension in your office style once the plan settles. ### What dimensions are included? Plan: overall chain per axis and a chain across wall axes. Elevations and sections: level marks. No opening or detail dimensions. Dimensions can be switched off. ### How are trees and furniture drawn? One convex-hull outline per instance on L-PLNT, I-FURN, E-LITE or P-FIXT. Full geometry or no assets are the other two modes. Silhouettes took the Mirror Lake file from 232 MB and about 930,000 polylines to 1.6 MB and 3,239. ### What does a hand-drawn concept set have that this DXF does not? Blocks, hatches, title block and layouts, associative dimensions, opening and detail dimensions, hidden-line removal, line weights, editorial judgement. The DXF has seven views that agree exactly and computed room areas. ### Can I get the DXF without the 3D model? No. It is derived from the parametric model; there is no image-to-DXF. The model is open to every account, 60 to 150 credits to generate; export is free and unlimited. --- **Try Nuit free — 300 credits (12 images), no card required.** Open the [example DXF](/3d/examples/) in your own CAD first; if the layer table fits how you draw, request 3D access from the studio. [Start your project →](https://nuit.archi)