Model on a site plan from a DWG or DXF

ModelCraft can bring in the lines of a 2D CAD drawing, a site plan or a floor plan, and lay them on the ground so you can model on top of them.

Import the drawing

1. Click Import in the File group (or drop the file on the 3D view).
2. Pick a .dwg or .dxf file.

A large DWG takes a moment: the status bar says "Reading plan.dwg…" until it is in.

1. If the drawing does not say what its units are, a dialog titled "Drawing units" asks: "What is one drawing unit?" Choose Inches, Feet, Millimeters or Meters. Most US site plans are drawn in feet, architectural plans in inches, and metric plans in millimeters.

The drawing arrives as a group of edges on the ground, selected, and the view zooms to it. The status bar says how many edges came in, for example "Imported site.dwg: 1697 edges on the ground, in a group. Explode it to draw on it directly."

What comes in

• Lines, polylines (including their arcs), circles and arcs, and blocks with everything in them, from model space only. Curves become short straight pieces.
• Everything lands flat on the ground, as edges. No faces are made.
• Not imported: splines, ellipses, hatches, text, dimensions and other object types. The status bar lists them by type, such as "Not imported: 12 TEXT, 3 HATCH." Anything on a layout (paper space) is left out too, without being listed.
• Layers are not kept: all lines come in alike.

If the drawing is far from its origin (state plane coordinates, for instance), it still imports, but it may land far from ModelCraft's origin. Drawings reaching more than 10,000 km from their origin are refused: move the drawing nearer to 0,0 in the CAD program first.

Trace it into faces

The imported lines rarely close neatly into faces by themselves. Two ways to work:

Keep the plan as an underlay (recommended)

1. Leave the plan as its own group.
2. Draw your building on top with Rectangle and Line, snapping to the plan's corners ("Endpoint") and edges ("On edge").
3. Push/pull your faces up. The plan stays untouched underneath, and you can erase the whole group later with one click.

Snapping works across groups: you can snap to the plan's corners without opening it.

Draw on the plan's own lines

1. Select the plan group and click Explode. Its lines become loose edges.
2. Where a closed outline should be a face, draw one line over any of its edges with Line, from corner to corner. When the outline is closed and flat, the face usually fills in. If it doesn't, look for a gap or an overlap in the outline and draw over it.
3. Push/pull it.

This works best on a clean plan. On a busy survey, tracing on top is faster.

Troubles

• "This is a binary DXF. Save it as ASCII DXF and try again." Save the DXF again from the CAD program as ASCII (text).
• "…has no lines, arcs or circles in model space to bring in." The drawing is probably all on layouts, or all text and hatches.
• "This drawing could not be read (…). It may be damaged, or saved in a DWG version the reader does not handle…" The brackets say why, for example "DWG version AC1009 is not supported". Save it as a DXF, or as a DWG from AutoCAD 2000 to 2018, from the CAD program.
• The plan is the wrong size: you picked the wrong unit. Undo (⌘ZCtrl+Z) and import again, or scale the group by the right factor (12 between feet and inches, 25.4 between inches and millimeters).