IFCtoFDS

Open IFC

IFCtoFDS Guide

Review IFC geometry, convert it into FDS geometry, then inspect the result before saving.

Quick Start

Open a building .ifc file and inspect the imported model.
Pick an Opening approach (HOLE is recommended), set FDS cell / voxel size, and the aperture policy.
Press Convert to FDS. Conversion runs in the background.
Use Overlay, FDS, and IFC views to compare geometry. Toggle FDS HOLE to show or hide carved openings.
Use the save icon to download the converted .fds file.

Conversion

FDS cell size: Target simulation mesh resolution written to &MESH.
Voxel size: Grid used to approximate IFC solids as merged OBST blocks.
Opening margin: Extends opening masks through walls so doors and windows remain clear.
Hole voxel policy: Smaller retains borderline wall cells; Larger removes them for a wider opening. Only relevant in Voxelization mode.
Opening approach: HOLE (recommended) emits one continuous &OBST per axis-aligned wall/slab plus rectangular &HOLE cutouts — cleaner FDS file and exact opening rectangles. Voxelization (legacy) emits a cluster of small &OBSTs that stair-step around each opening; use it for arched / curved / non-axis-aligned openings that &HOLE cannot represent.
OBST threshold: Lower = more elements voxelize into OBST (catches chamfered walls). Higher = stricter; only purely boxy shapes voxelize, the rest stay as detailed GEOM.
Closed window/door fills: Adds colored airtight &OBST closures (window blue / door brown) in the opening volume. With HOLE the closure perfectly refills the carved rectangle; the closure is written after every &HOLE so no HOLE can carve it.
Furniture, MEP and proxy solids: Includes review objects as blockers only when they should affect smoke flow.

Geometry Strategy

Walls, slabs, rectangular columns, openings, doors, and simple blocks become &OBST. Curved or irregular objects such as complex stairs remain detailed triangle &GEOM and render slightly darker so the two outputs are easy to tell apart.

Flat slabs whose IFC representation the parser couldn't extrude (some Revit-exported floors and tapered roofs) are auto-inflated to a default thickness during voxelization so their L / U / T floor outline is preserved instead of being collapsed to a single bounding box.

Select generated GEOM items and press Voxelize selected GEOM to OBST to reroute those items through voxelization. (This re-converts in place without replaying the reveal animation.)

Toolbar and View

Open IFC: Loads a local IFC building model.
Moon / sun: Switches between the light and dark interfaces.
Footprints: Enters first-person walk mode. Click a floor or stair surface to place yourself.
Reset: Fits the camera back around the visible model.
Save: Downloads the most recent generated FDS file.
Layer checks: Show or hide FDS meshes, OBST, HOLE, VENT, GEOM, IFC references, optional IFC edges, and the ground grid. HOLE markers render as ghost-cyan boxes so the closure colour behind them shows through.
Opacity sliders: Fade IFC and FDS independently. Zero hides the layer completely.
Clip bars: Six sliders along the bottom of the viewer cut the scene to a sub-volume; for FDS, primitives whose full bbox sits inside the clip stay visible and the rest disappear cleanly (no slicing through).

Selection and Walk Mode

Clicks pick the closest visible hit first, so a click on a visible front wall lands on that wall rather than a HOLE or back-wall element behind it.

Click	Select one object and inspect its IFC source mapping.
`Shift` + click	Add or remove objects from a multi-selection.
`Shift` + drag	Marquee-select every OBST / HOLE / GEOM / IFC mesh whose centre lies inside the rectangle.
`1`–`6`, `0`	Snap to front / back / left / right / top / bottom and isometric camera views.
`←→↑↓`	Orbit the camera around the model. `Shift`+`↑`/`↓` dollies in/out; `Shift`+`←`/`→` strafes the pivot.
`Ctrl` + `Z`	Undo the last delete or voxelize action.
`WASD`	Walk horizontally.
`Space`	Jump. Stairs are climbed automatically while walking.
`Shift`	Walk faster.
`Esc`	Leave walk mode and return to orbit inspection.