Image to SketchUp Face

The TracePen SketchUp plugin traces a raster image into native Sketchup::Face entities — real faces you can push-pull, extrude, group, intersect like any hand-drawn geometry. One face per region, holes as native inner loops, no triangle mesh.

Premium-only. Requires SketchUp 2022 or newer.

Why not just import DXF Faces?

DXF Faces are triangle meshes. Each region becomes dozens of triangles that need Merge Coplanar Faces on import to look like a single face — and the post-merge topology still differs from native geometry.

The plugin uses SketchUp's own EntitiesBuilder#add_face(outer, holes:) (API v10, SU 2022+). Each polygon is one face with proper loop topology — not triangulated.

	DXF Faces import	TracePen plugin
Faces	Triangles (needs Merge Coplanar)	Native Face, one per region
Holes	Triangulated away	Native inner loops
Re-trace same image	Re-import → duplicate geometry	Edits the existing component
Colour → material	Manual re-apply	Auto: one material per layer
Layer grouping	CAD layer per colour	SU Group per colour
Round-trip fidelity	Lossy (triangle soup)	Lossless (polygons)

Install

1. Purchase Premium → receive the tracepen.rbz file.
2. In SketchUp: Window → Extension Manager → Install Extension → select tracepen.rbz.
3. Accept the signed-extension prompt.
4. Restart SketchUp.

SketchUp 2021 and older are refused at load with a pointer back to the web app — EntitiesBuilder#add_face(holes:) doesn't exist there.

Workflow

1. Extensions → TracePen → Open (or toolbar icon).
2. A dialog opens with the full TracePen UI (same controls as the web app).
3. Upload a PNG or JPG.
4. Adjust colour count, noise filter, minimum region size to taste.
5. Click Trace.
6. Set width in mm or in.
7. Click Load to SketchUp.
8. The plugin streams layer-by-layer; a progress counter shows N/Total.

A typical 1500 px, 8-colour image lands in a few seconds.

What you get in the model

ComponentDefinition "TracePen"   ← one per document, re-used on re-trace
├─ Group "Layer 00"              ← one per colour, material applied
│   ├─ Face (outer + holes)
│   ├─ Face (outer + holes)
│   └─ …
├─ Group "Layer 01"
│   └─ …
└─ …

• One top-level component. An instance is placed at origin. The definition's GUID is stored as a model attribute so re-trace can find it.
• One group per colour layer. Named Layer 00, Layer 01, …
• One native Face per polygon. Inner loops are holes.
• One SU Material per layer, coloured to match the traced region. Named TracePen_RRR_GGG_BBB.

Every face is editable exactly like hand-drawn geometry — push-pull works, extrude works, intersect works, Solid Tools works.

Re-trace in place

Re-open TracePen in the same document and load again → the existing component is cleared and refilled, not duplicated. The stored GUID guarantees the plugin finds the same definition.

Handy when you want to:

• Swap the source image (e.g. higher-resolution scan).
• Adjust colour count or tracing parameters and re-push.
• Re-apply after the image's palette has been edited.

Undo

Each Load to SketchUp is a single SketchUp operation. One Ctrl+Z rolls the entire insert back — no half-inserted geometry left behind.

Tolerances (internal)

Vertices snap to a 0.025 mm grid — SU's internal point tolerance is 0.001" ≈ 0.0254 mm. Edges shorter than 0.05 mm drop. Near-collinear vertices are removed so add_face doesn't reject polygons as "not planar".

These are wired in — you don't configure them.

Frequently asked

What SketchUp versions are supported?

SketchUp 2022 and newer (Make, Pro, Studio). Earlier versions lack EntitiesBuilder#add_face(holes:).

Does it work on SketchUp Free (web)?

No — SketchUp Web doesn't load .rbz extensions. Use the online converter with DXF Faces export instead.

Is it signed?

Yes — distributed as a signed Trimble Extension. Extension Manager loads it without an "untrusted code" prompt.

Is the dialog offline?

Tracing runs locally after install — no network call, no account required beyond the one-time purchase.

Can I edit the traced geometry afterwards?

Yes — it's real SketchUp geometry. Faces are native, loops are native, materials are SU Material entities. Every SketchUp tool works on it.

Does it use AI?

No. Same deterministic pipeline as the web app: ADU quantization (Celebi 2014) → Mumford-Shah region merge (arXiv 2409.15940, 2024) → grid-walk contour trace → Potrace Bezier fit (Selinger 2003). Identical input always produces identical faces.