Tracing a CAD drawing (DWG / DXF Underlay)

You can import an existing AutoCAD drawing (.dwg or .dxf) as a precise CAD underlay and trace native Jodu walls, doors, windows, and stairs directly over it.

The drawing is an immutable reference. Your wall clicks can suggest connected wall runs; those suggestions become native Jodu walls only when you review and create them. Openings and stairs use the existing assisted tracing gestures.

Required decisions appear in a centered panel. While a decision is pending, wall highlighting and tracing pause; you can still pan and zoom to inspect the drawing. When you need to work on the canvas, the instructions and tools move below it. Only the current gesture is active, such as selecting the plan area, measuring a distance, aligning drawings, or tracing walls. The side panel keeps drawing settings and a step list, one list per level: Plan area → Walls → Openings → Stairs → Next level (upper levels add Line up with the level below). Ticks come from what is saved, so you can finish one level, do other work, and come back to trace the next.

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How do I attach a CAD drawing?

1. Open Plans on the level you want to trace (e.g. Ground).
2. Click the project name at the top, then Add CAD reference…, and choose your .dwg or .dxf file. The drawing appears behind the plan.
3. Click Set up CAD. The centered panel starts with Check drawing scale.
4. Check the detected unit (Millimetres, Metres, Inches, Feet) and click Scale looks right. If the drawing looks wrong, see Drawing looks too big or too small.

Once a drawing is attached, Draw wall → Trace CAD returns you to the trace steps.

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How do I pick my plan from a sheet with several plans?

A sheet often holds several plans, elevations, and title blocks side by side. The Plan area step starts picking straight away:

1. Move over the sheet. The drawing group under the pointer is outlined.
2. Click the plan you want, or drag a box around it if the outline is not right.
3. Click Use this area. Use Select again to change it, or Use entire sheet when the file holds one plan.

The box selects the reference area only. It does not define the plot or change the building model. On an upper level the area you chose for the level below is outlined and Use Ground area reuses it, since a sheet usually holds every floor's plan.

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How do I trace walls?

1. Choose your wall type in the wall options bar (e.g. 230 mm brick).
2. Zoom in and hover inside a wall. Both detected faces light up when a paired trace is available; a single face starts the manual two-face workflow.
3. Click inside a wall, between its two face lines, to take both faces at once, or click one face and then the opposite face.
4. Confirm the measured width (Use standard 9″, or map it to another wall type). The run is staged in purple.
5. Trace the other walls. Runs that meet join at corners.
6. Click Review & create walls.

A click takes the whole straight face, joined across small drawing breaks and across junctions where a crossing wall meets it. It stops at a door or window opening, a turn, or a layer change, so openings stay openings. Where a wall already exists on that line the new wall starts where it ends.

With Follow walls enabled in the bottom tools, Jodu continues from your click through supported corners and branches. Light cyan bands are Suggested walls; purple bands are Confirmed traces. Amber marks indicate where recovery stopped: click inside the next wall to continue. Turn Follow walls off to trace each wall yourself. Clicking a suggested wall confirms it.

How do I remove incorrect suggestions?

• Choose Remove guesses, then click the wrong bands. Each click selects one run; clicking a selected run again keeps it. Check the orange highlights and press Remove selected. Confirmed traces are protected.
• To select a connected set, select a run and enable Follow connected guesses. Clicking a highlighted run excludes it and stops traversal through it. Other paths around a loop can still reach neighbouring runs, so check the preview.
• To remove part of one long run, select it and choose Remove section. Click the two ends of the unwanted section, then Remove highlighted section. Both remaining portions stay in the draft.
• Discard last flood previews all suggestions from the latest expansion; press Remove selected to apply. It preserves the wall you explicitly clicked.
• Cancel or Escape leaves the draft unchanged. Undo removal restores the latest applied correction before you make another explicit trace/edit.

Removed spans stay rejected during automatic recovery for this trace session. An ordinary deliberate wall click always overrides rejection over the run you trace and can start detection again. It does not restore unrelated rejected bands. Once walls are created, use the native Wall tools to edit or delete them.

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How do I add doors and windows?

1. Open the Openings step (it needs walls on the level).
2. Gaps between two walls of equal thickness, 0.2–3 m apart, are outlined. Click one to stage that opening jamb to jamb, or click both jambs of any other opening.
3. Choose Door, Window, or Open passage. For a door, Flip hinge and Flip side show the swing on the plan before you add it.
4. Click Add. The step stays open for the next gap; press Done with openings when finished.

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How do I fit a stair from the drawing?

Stairs are traced with a few measurements. Jodu never traces the individual steps: it fits a stair into the outline you give it.

1. Open the Stairs step. A stair needs the level above; if there is none, click Add level. You stay on this level.
2. Click the lines along the stair's outer edges. From two edges, Use suggested box spans them; four edges close a rectangle and six an L.
3. Click between two neighbouring step lines to measure the tread depth.
4. Click the outline edge where the stair starts.
5. Click Fit stair. The Stair tool proposes stairs that fill the outline, over the drawing. Review and Place as usual.

The step is optional; click Skip stairs to leave it for later.

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How do I trace the next level?

1. Open Next level to see every level's state, then Add level and trace (or choose an existing level).
2. Plan area: click Use Ground area to reuse the region you picked below.
3. Line up with Ground: click a corner on the drawing, then the same corner on the walls below, twice. Drawing clicks snap to line ends, and clicks on the level below snap to wall corners. Skip and start tracing walls keeps the drawing centred.
4. Trace walls and openings as before.

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Drawing looks too big or too small

Symptom	Cause	Fix
Drawing appears microscopic or huge	Wrong CAD unit declared in the file	Choose the right unit (Millimetres, Metres, Inches, Feet) in the unit field, then check a known wall width
Walls measure implausible widths (e.g. 2 mm or 7 m)	Wrong unit	Same fix
"Calibration failed"	Picked points were identical	Pick two distinct endpoints of a known distance
Underlay obscures new walls	Opacity too high	Lower Underlay opacity to 30%
Underlay disappeared	Drawing visibility is off	Turn on Keep drawing visible after tracing in Drawing appearance
Cannot snap to CAD lines	Pointer is too far from the line	Zoom in closer to the wall corner
A batch of walls is rejected	It overlaps a wall already on the level	Trace the new walls again; overlapping stretches are left to the existing wall

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Related

• Reference image tool: tracing PNG, JPG, or PDF underlays
• Wall tool: drawing native structural walls
• Stair tool: placing and editing stairs
• Precision input: snapping, typing lengths, and axis constraints
• Plan workspace: complete tools index

Hover inside a wall to preview both detected faces, then click to trace that pair. Moving close to a face keeps the paired gesture while you remain inside a supported wall band. If only one face lights up, clicking starts the manual first-face selection; select its opposite face to finish the pair.