SketchUp SKP — 3D Architectural Modeling Format from Trimble
SketchUp SKP is a proprietary binary 3D format developed by @Last Software in 2000 and today owned by Trimble. Over a quarter century SKP became the de-facto standard for 3D modeling in residential architecture, interior design, landscape and urban massing studies — where rough idea exploration speed matters more than BIM parametrism. Edge-and-face geometry, an inferencing engine, components, and 3D Warehouse with millions of free models made SketchUp the «pencil-and-paper of 3D». On osm2cdr.ru we don't export SKP directly (Trimble keeps the spec closed) but generate OBJ/glTF mass-models of OSM buildings that an architect imports via File → Import for context massing in daylight studies and shadow analysis.
History: @Last Software → Google → Trimble
In 1999 in Boulder, Colorado, Brad Schell and Joe Esch founded @Last Software with a goal to build a 3D tool where the first workday goes into designing, not learning the interface. In August 2000 SketchUp 1.0 shipped — a program with a revolutionary push/pull metaphor (draw a 2D contour and «push» it into volume) and an inferencing engine that snapped the cursor to midpoint/endpoint/parallel/perpendicular without explicit snap commands.
In March 2006 Google acquired @Last Software for Earth integration — they needed a mass tool for community modeling through Building Maker. Google made the desktop version free alongside paid Pro and in 2007 launched 3D Warehouse (~7 million objects today). In April 2012 Trimble bought SketchUp from Google for $45 million — Earth Building Maker had been retired and SketchUp produced no Google revenue. Trimble integrated SketchUp into its geospatial/construction ecosystem next to Tekla Structures and Trimble Connect. In 2017 web-based SketchUp Free launched (replacing legacy SketchUp Make 2017). In 2020 — top-tier SketchUp Studio with Sefaira (energy analysis) and Scan Essentials. 2026 tiers: Go (web) $129/year, Pro (desktop) $349/year, Studio $1199/year. Release cadence — «one major version per year» (2024, 2025, 2026), each changes SKP schema.
Inside SKP: edge-and-face, components, tags
SKP is a proprietary binary with closed specification. Trimble provides SketchUp SDK (C++/C#/Ruby) through an abstracted API — nearly any third-party program uses this SDK.
Edge-and-face geometry. Unlike polygon-mesh (OBJ/FBX/glTF, base unit = triangle), SketchUp works in an «edges define faces» paradigm: a closed 2D edge contour automatically generates a face inside. Natural for architects, frustrating for game developers without vertex-level control.
Inferencing engine is the UX heart. The cursor snaps to endpoint (green), midpoint (blue), intersection (red), parallel/perpendicular contextually — you can «hook» a distant vertex without explicit snap commands.
Components vs Groups. Group — simple wrapper. Component — reusable block: all instances share single definition. Components are the basis of efficient workflow (tree in landscape, window in facade, typical chair). Saved as separate .skp and published in 3D Warehouse.
Tags (formerly Layers). Before SketchUp 2020 — layers in CAD tradition; in 2020 renamed to tags. Caveat: tags are not containers — geometry «lives» in model space or group/component, tag only tags it for visibility filtering.
Styles — non-photorealistic vector rendering (hand-sketched, watercolor, blueprint), a feature for conceptual presentations. Material system is simpler than PBR — texture + color + alpha; for normal/roughness/metalness plugins are needed (V-Ray, Enscape).
SKP backwards compatibility is a principal nuance: newer SKP don't open in older versions (2024 won't open 2025). In collaboration all on the same major version, otherwise sender does File → Save As → SketchUp 2024 for downgrade.
.skb backup files are auto-created on every save. LayOut and .layout files — a separate app bundled with Pro for paper-space presentations with references to linked SKP + 2D annotations.
Use cases: architecture, interior, landscape, urban massing
Residential architecture (90% market share for small-medium studios) is the main use case. Rough house massing in 30 minutes, components for windows/doors, sun-study animation in a couple of clicks. An architect makes 5-10 massing variants in a day; Revit needs an order of magnitude more setup but produces BIM data.
Interior design — designers model rooms, place furniture from 3D Warehouse (IKEA, Herman Miller, Knoll publish catalogs), render through V-Ray/Enscape. SketchUp + 3D Warehouse + V-Ray is the typical toolchain.
Urban planning (massing studies) — KPF, SOM, Foster + Partners use SketchUp for early-stage: proposed tower next to context, height/setback compliance, shadow impact. Context is imported from CityGML or OSM building footprints + heights.
Landscape design — Land F/X plugin (tree libraries, irrigation, hardscape, grading). Topography through built-in Sandbox tools.
Woodworking shop drawings — an unexpectedly major category. Furniture makers design pieces, generate cut lists (CutList, OpenCutList), production drawings in LayOut. Low entry barrier vs SolidWorks.
Theatre set design and video game level design (white-box prototyping → FBX/OBJ export → Unity/Unreal as placeholder).
Software, plugins, render engines
Tier ecosystem. Free (web), Go ($129/year, web+iPad), Pro ($349/year, desktop, LayOut, DWG/DXF/IFC/FBX/OBJ/COLLADA), Studio ($1199/year, +Sefaira+Scan Essentials+V-Ray). Legacy: SketchUp Make 2017 — last free desktop from Google era, officially unsupported since 2018, downloadable from web archive.
3D Warehouse — ~7M free models: from professional catalogs (IKEA, Knoll, Velux) to student-grade user submissions.
Extension Warehouse — Ruby plugins. Top: Curic, Profile Builder, Vertex Tools (vertex-level editing), CleanUp³, Skimp.
Render engines — SketchUp has no built-in photorealist: V-Ray (Chaos, $471/year, industrial standard), Enscape (Chaos, $58/month, real-time), Twinmotion (Epic, Unreal-based), Lumion ($1499/year).
3D printing — CADspan plugin or native STL → Cura/PrusaSlicer. SimLab — FBX/OBJ/STL/3DS interop, Composer, VR Viewer.
GDAL / OGR support — absent. Proprietary binary with closed schema doesn't admit the open-source ecosystem. Workaround: SketchUp Pro export → OBJ/COLLADA/glTF → GDAL. FreeCAD reads SKP through sketchup_importer add-on (uses SDK runtime).
SketchUp in osm2cdr workflow
We don't generate SKP directly (Trimble doesn't publish spec, integration through SDK would require Windows/macOS build infrastructure in Docker-Celery), but offer OSM building context in open intermediate formats that SketchUp Pro imports via File → Import.
Workflow. The architect models proposed building in SketchUp Pro → in parallel on osm2cdr.ru selects a bbox around the site (500 m × 500 m or 1 km × 1 km) and format glTF/GLB (preferred) or OBJ → backend generates a 3D model of surrounding buildings: building footprints from OSM PostGIS extruded by height tag, or building:levels × 3.5m, or by building-type heuristics → architect imports through File → Import → glTF, assigns tag «OSM Context» for visibility toggle → ready for daylight studies (built-in Shadow Bearings), view corridor analysis, height comparison.
Limitations. OSM heights often missing — filled only for landmark buildings; fallback heuristics (residential 12m, commercial 15m, industrial 8m) are not accurate, require manual correction for shadow analysis. OBJ import may lose materials (MTL collapses to default). SketchUp 2017 vs 2020+ — tags vs layers, functionally identical but script automation breaks. Polygon count — 1 km² downtown bbox gives 50K-200K triangles; SketchUp comfortable up to ~500K, above — viewport degrades. Coordinate origin — export to local metric CRS, run Camera → Zoom Extents after import. For city-scale — export to CityGML/3D Tiles (LoD support).
Strengths and weaknesses
Strengths. Low entry barrier (1-2 days). Inferencing eliminates 80% snap commands. Push/pull is natural. Components + 3D Warehouse save hundreds of hours. Render ecosystem (V-Ray/Enscape/Twinmotion/Lumion) is the broadest. LayOut for paper-space. Ruby API.
Weaknesses. Proprietary — vendor lock-in. One-sided backwards compatibility. Edge-and-face unsuitable for organic modeling (Blender/Maya/ZBrush are better). Material system primitive. Not BIM. Subscription-only since 2020. Performance degrades above 500K triangles.
FAQ
Can SKP be opened without SketchUp? SketchUp Viewer (free read-only from Trimble) opens any SKP. FreeCAD through sketchup_importer add-on. Blender — no native, conversion through Pro export needed.
SKP vs OBJ vs FBX vs COLLADA? In SketchUp ecosystem — SKP. For Blender/Maya/3ds Max — FBX or COLLADA. Web/AR/VR — glTF. Simple interchange — OBJ.
Why doesn't 2024 open 2025? Versioned proprietary binary, each major version changes schema. Workaround: sender does Save As → SketchUp 2024 (downgrade, losing new features).
Make 2017 for commercial work? EULA forbids — it's personal/educational. Trimble enforces weakly, but strictly Pro is required.
SketchUp for BIM? No — no parametric constraints, schedules, IFC-native (only import/export). For BIM — Revit/ArchiCAD. SketchUp is ideal for early-stage exploration; hybrid «concept in SketchUp → BIM in Revit» is typical.
How to use osm2cdr context in SketchUp? Export to glTF (.glb) (preserves materials better), import in Pro 2024+ via File → Import → glTF, then Make Component, tag «OSM Context», Lock.
Conclusion
SketchUp SKP is a format defining the boundary between «professional CAD» and «artistic 3D»: faster than AutoCAD/Revit for conceptual design but doesn't reach BIM; more powerful than Blender for architecture but loses in organic sculpting. This niche — early-stage architecture, interior, landscape, urban massing — is so in-demand that SketchUp has held a dominant position for 25 years through three owners. Proprietary binary is vendor lock-in as a reasonable tradeoff for UX.
On osm2cdr.ru we provide OSM building context in OBJ/glTF through /api/render for integration into SketchUp workflow.
Try OSM to glTF export and import into SketchUp Pro 2024+ via File → Import → glTF.
Related
- OBJ — simple text 3D format from Wavefront
- COLLADA — open standard 3D interchange from Khronos
- glTF — compact JSON format for web/AR/VR from Khronos
- FBX — industrial 3D format from Autodesk
Sources
- SketchUp (Trimble) — sketchup.com
- 3D Warehouse — 3dwarehouse.sketchup.com
- SketchUp SDK — developer.sketchup.com