BIM Viewer

The BIM viewer loads, navigates, and interrogates IFC models independently of their map context. It is built on That Open Engine — an IFC engine on top of Three.js that gives full access to BIM geometry, metadata, and property sets while honouring openBIM standards.

Goal

Load a BIM model, navigate it in 3D, read its property sets, and use the openBIM tools (IDS validation, BCF topics) for coordination work.

Prerequisites

• A CDT account with User or Admin role (to upload).
• An IFC file. Public test files are at the buildingSMART sample repository.

Load a model

Goal: get an IFC into the viewer.

1. Open the BIM Viewer from the left sidebar.
2. Drag the IFC file onto the viewer, or use the File tab → Upload button.
3. The platform converts the file to Fragments 2.0 (.frag) on the server. The progress bar tracks parse → conversion → load.
4. Once finished, the model appears in the scene and is added to the File tab list.

The conversion happens once. Subsequent loads stream the cached .frag and are much faster.

Supported formats beyond IFC: glTF / GLB, FBX, OBJ, Collada, DXF, LAZ / LAS / COPC.

Result: the model is visible in the viewport and selectable.

Navigate in 3D

Control	What it does
Left-click + drag	Orbit around the model
Right-click + drag	Pan
Scroll wheel	Zoom
Double-click	Set the orbit pivot point
Fit Extents (toolbar)	Frame the full model in the viewport

Result: smooth navigation in any direction, with predictable pivot behaviour.

Inspect element properties

Goal: read the IFC schema data for a specific element.

1. Click any element in the 3D scene.
2. The right panel populates with:
   • Entity attributes and geometry
   • Property sets (Psets)
   • Quantity sets (Qsets)
   • Material assignments
   • Associated IfcTask entries
   • Spatial container relationships
3. Use the search field to filter large property trees.
4. Hold Shift and click multiple elements to compare attributes side-by-side.
5. Click Export to save the current selection's properties as JSON or CSV.

Result: the property panel shows the full IFC data for the selected element(s).

Cut a section

Goal: see inside the model with a clipping plane.

1. Click Clipping plane in the toolbar, then Add clipping plane.
2. Double-click any face on the model — a section plane appears aligned with that face.
3. Drag the arrow handle to adjust depth.
4. Press Enter (or Cancel add clipping plane) to finish. The section stays and its arrow is still draggable.
5. Backspace removes the plane under the cursor, Esc removes every plane, and Ctrl+Z undoes the last change.

Result: the model is sliced at your chosen plane and the interior is visible.

Browse and filter the model

Goal: navigate to elements via a list rather than hunting in 3D, and control what is visible.

Open the Layers tab in the left panel. It holds two collapsible groups, each with a switcher between two views:

Group	Views	What it lists
Drawings	Floorplans / Elevations	Generated 2D views of the model
Classifier	Spatial / IFC Classes	The IFC spatial tree, or every IFC class in the model

Collapsing one group gives its height to the other, and the divider between them can be dragged.

Drawings

Selecting a storey generates its floorplan and frames it in the view. Below the drawing, a Layers list gives every IFC class in the plan its own visibility switch and colour picker, so you can mute furniture, recolour the structure, and so on.

Rooms

Rooms (IFCSPACE) get their own Rooms layer, drawn the way most authoring software does: a translucent light-blue fill over the room's footprint, an X across it, and the room's name at its centre.

The layer starts off, because room fills sit over the linework underneath. Switch it on from the Layers list.

Picking a colour for the layer replaces the light blue and hides the X — the cross reads as "unstyled room", so it stops making sense once a room carries a deliberate colour. The name tags stay either way, since they are information rather than styling.

The fill follows the room's real footprint, so an L-shaped room is drawn as an L rather than as its bounding rectangle.

Spatial

The spatial view is the IFC containment hierarchy, rooted at each model's building:

Rows show each element's name (Basic Wall:Generic 200mm) with its IFC class beside it. Every loaded model contributes its own building, so a federated set appears as sibling branches in one tree.

IFC Classes

The classes view groups the same elements by what they are rather than where they sit — one row per IFC class (IFCWALL, IFCSLAB, IFCDOOR, …) with the number of elements in it. Class names are shown exactly as the IFC defines them, in every language. Only classes that have geometry are listed.

Classes hidden by default

Three classes start hidden, because their geometry envelops the building and would obscure everything behind it:

Class	Why
IFCGEOGRAPHICELEMENT	Topography in IFC4
IFCSITE	Topography in IFC2x3, where the terrain hangs off the site
IFCSPACE	Room volumes

Which class topography lands in depends on the schema version and the authoring software's IFC export mapping — some export topography geometry as IfcSite, others as IfcGeographicElement — so both cases are covered. They are still listed — switch one on to show it. The choice sticks for the rest of the session; a model loaded afterwards comes in with its own topography and spaces hidden.

IFCBUILDINGELEMENTPROXY is not hidden by default. Some IFC2x3 exports put terrain there too, but it is also the catch-all for any element the authoring software has no specific IFC class for, so hiding it would take real building geometry with it. Switch it off manually if your export needs it.

Select, hide, isolate

Every row in both views supports the same three actions:

Action	How	Effect
Select	Click the row	Highlights the element(s) in 3D and opens the properties panel
Hide / show	The row's switch	Toggles visibility of the row and everything under it
Isolate	The crosshair button (appears on hover)	Hides everything else
Recolour / fade	The small circle at the left of the row	Sets a colour and an opacity for the row and everything under it

These act across all loaded models, so isolating IFCWALL leaves only walls in a federated set. Use the eye button in the view's toolbar — or Selection → Show all in the viewer toolbar — to bring everything back.

The search box at the top of the tab filters both groups at once and opens the branches leading to each match.

Colour and opacity

Every row carries a small circle at its left. It stays an empty outline until you use it, then fills with whatever colour and opacity you gave that row.

Click it to open the picker: a colour well and an opacity slider. Both are optional and independent, so you can tint a class without fading it, or fade a storey while it keeps its own colours. Reset in the picker clears just that row.

Colouring cascades. Tint a storey in the Spatial view and everything inside it takes the colour; a wall you had already coloured separately keeps its own, whichever order you set the two in. Setting only an opacity on that wall leaves it the storey's colour and fades it.

The two views can name the same element, since IFCWALL and a storey overlap. Whichever view you touched most recently wins the overlap, and undoing that change hands the elements back to the other view.

Control	Where	Effect
Reset	Inside a row's picker	Clears that row
Reset colours	The brush button in the view's toolbar	Clears the whole view, leaving the other one alone
Undo	Ctrl+Z (Cmd+Z on macOS)	Steps back one colour or opacity change
Redo	Ctrl+Y, or Ctrl+Shift+Z	Puts the change you just undid back

Undo and redo cover colour and opacity only, not visibility or selection, and they work anywhere in the viewer rather than only while the Layers tab is open. Inside the search box Ctrl+Z edits the text as usual.

A whole slider drag counts as one step, so undoing a fade takes one keystroke rather than one per tick, and redoing it lands where you let go. Making a new change after undoing drops the redo trail, as everywhere else.

Colours last for the session. They are not saved with the model, and they are not shared with anyone else looking at it.

Result: you can find any element by location or by class, reduce the scene to just what you are working on, and colour-code what is left.

Validate against an IDS file

Goal: check whether the model satisfies an Information Delivery Specification.

1. Open the File tab.
2. Click Import IDS and pick your .ids file.
3. The viewer evaluates each requirement against the model and lists pass/fail counts.
4. Click any failed requirement to see the offending elements highlighted in 3D.

Result: every requirement in the IDS shows pass/fail with element-level traceability.

Track issues with BCF topics

Goal: open a coordination issue against a specific element and a specific viewpoint.

1. Click the element(s) related to the issue.
2. Open the Topics tab → New topic.
3. Fill in title, description, responsible party, status, and priority. The current viewpoint is captured automatically.
4. Save the topic.
5. Export to .bcf from the topic list to share with teams using Revit, Archicad, or any compliant authoring tool.

Result: the topic is saved against the element's GlobalId and viewpoint, and exports as a vendor-neutral .bcf.

Generate a floor plan

Goal: view a 2D plan of any storey.

1. Open the File tab.
2. Floor plans are auto-generated for every IfcStorey — pick one from the list.
3. The viewer switches to a top-down 2D plan with the same measurement and annotation tools as the 3D view.

Result: a precise 2D plan of the chosen storey, navigable like the 3D view.

Toolbar quick reference

Tool	Description
Clipping plane	Section cut from any face.
Fit extents	Reset the camera to frame the model.
Add feature	Import IFC, IDS, or BCF; upload DXF; add media.
Measurements	Distance, angle, area, and element volume.
Share	URL + QR code encoding camera position and asset ID.

Settings reference

The Settings tab in the left panel controls the Three.js scene:

• Theme — system, dark, light.
• Camera — perspective vs orthographic; FOV, speed, frustum.
• Grid — toggle, resize, recolour.
• Lighting — position, intensity, colour.
• Renderer — gamma correction, ambient occlusion, gloss, outline effects.

DXF / CAD overlay

Upload a .dxf to overlay a 2D drawing inside the 3D scene. The platform parses it through DXF-Viewer into Three.js lines. You can position, scale, and rotate it relative to the IFC coordinate system, and toggle CAD layers individually.

Supported openBIM formats

Format	Purpose
IFC	Building model geometry + metadata
IDS	Information delivery requirements + validation
BCF	Issue tracking and coordination
bSDD	buildingSMART Data Dictionary — element classification

Related

• Concepts → BIM & IFC
• File Management
• Collaboration → BCF Topics
• Components → BIM Tools