One cylinder imported from STEP and IGES

The two source files describe the same analytic cylinder, exported as STEP and IGES. Their matched mesh results make a reproducible import example with a known physical scale. The known radius and height provide independent checks on the imported mesh.

How this was measured

Generate a cylinder of radius 10 mm and height 20 mm using Open CASCADE, then write each exchange format from that shape. Import both through occt-import-js with 0.1 mm absolute linear deflection and 0.5 radians angular deflection. Measure triangles, axis-aligned mesh bounds, and edge incidence using the same inspection routine.

Recorded output from this experiment
Measurement	Value
step / triangles	124
step / dimensions	20 × 20 × 20
step / units	mm
step / open Edges	0
step / inconsistent Edges	0
step / non Manifold Edges	0
step / degenerate Triangles	0
step / components	1
iges / triangles	124
iges / dimensions	20 × 20 × 20
iges / units	mm
iges / open Edges	0
iges / inconsistent Edges	0
iges / non Manifold Edges	0
iges / degenerate Triangles	0
iges / components	1

What the result does not establish

Both source exporters and the browser importer use Open CASCADE. Agreement here is not an independent interoperability certification between different CAD systems. Complex assemblies, unsupported entities, trimming behavior, and other source exporters need their own examples. The browser inspects the resulting mesh, not native modeling history.

Try these files

These samples were created by this project and released under CC0. They contain no visitor files. Sizes and SHA-256 hashes identify the exact bytes measured in this experiment.

Project-created cylinder: radius 10 mm, height 20 mm. (STEP, 5,664 bytes)
SHA-256
0004159d7b2a121deb50aeba379c153ed27b412a8a38782a65513b3a58583a1e
The same project-created cylinder exported as IGES. (IGES, 7,857 bytes)
SHA-256
81274edc6d86ea10fe439b7077d4a0451159d16bc9802d4c778556425631a507

Use this result

STEP vs IGES: what one cylinder demonstrates

Versions and reproduction

Evidence generated 2026-09-05T21:13:29.140Z. The checked-in generator rebuilds the sample collection and measurements with one command:

node --experimental-strip-types scripts/build-workbench-evidence.ts

CAD source generation: scripts/build-workbench-cad.py with cadquery-ocp 7.9.3.1.1; checked-in analytic cylinder outputs. The STEP and IGES outputs are checked in so ordinary evidence rebuilds do not require Python.

@astrojs/cloudflare: 14.3.0
@cloudflare/containers: 0.3.7
astro: 7.3.1
fflate: 0.8.3
jose: 6.2.12
occt-import-js: 0.0.23
rhino3dm: 8.32.2
three: 0.185.1

Geometry source and generator SHA-256 hashes:

core/affine.ts: cff986695025f835e54c530ef654a3b7b19862d5f5feba08a361f2db708fbe65
core/bytes.ts: 850a1863a411549bbaf73e85d339dd3109fb57aca4e89e1cbeb0a06cdb3cc924
core/convert.ts: e9e96ecbb498338b85bc122a7e328ae9d96666b2dadce581e4f86e8b7b59689d
core/deflate-validation.ts: 7427464082422b2a484cb4b845e21a41dbb015ffddb83a4d1f938b6c32cb40f1
core/detect.ts: 4c64ca45732c4339749fed372b20e6996f17e1f4d307046ad71e047723ccf3e9
core/formats.ts: f037f0543d19f5ffebe97ea40450c5b646d6d5164ae4e816bf3dce6cf3685479
core/index.ts: 6dcf467a7b1952cf270fd834927404b19eb58bc6d1f2542d8c420bda90d4e3f7
core/inspect.ts: 44100ac51622e986e3ab63e49d6704dde539141454e273b76d5be70b5115a1ec
core/model.ts: bef860184a185c098d72d30a12cfaa7fe3199b96dbde0e65428b8f3bfe6c79a5
core/read/3dm.ts: f26a7d22c86dc6780ce218822eafa4cc5dbf76f35289a6266f6f2161bd84127e
core/read/3ds.ts: 0142d9f82937566220d6616c52800ffa856fff500bab3e26e90c0cdc0c6f7e32
core/read/3mf-package.ts: 11ad7a82d1dc5698412479d0c6351c5b88cfbc308ebee4a5d91fdc71d969af51
core/read/3mf.ts: 9378aa3156d5b908d4ce2ac551b76500247762de75a21b29ae0b2feb341a950e
core/read/amf.ts: b68b2de1c27d3c374ce4e2ce4215c8a6edcfbccac3e9a7ed0f623956cfe4afde
core/read/dae.ts: acf671ba4ea931ca4e958a67886978e61da9c7cb936cb835265f86d3b271b2c5
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core/read/fbx.ts: 33c87b835bf7ba11a2dd937fd78ff21a094076e9b9d95e7d24e40ea859c16bf3
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core/read/occt.ts: 1c129dc8ffb4f03bc992dd8940681acb92a4ed03271ce47485f3ac1533182117
core/read/ply.ts: 3cac9da6d62be20ae016cef751b01c14c0ebccd67d921107c56e8297835d2933
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core/read/stl.ts: ac53b792bd9cb8bff4366331fa0bb49844c7d6fcf9df47819cc75544e812dec9
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core/read/wrl-preflight.ts: 2a4ef48b020ef98b381ab33aa34266bb5c43de716e2e38256598d69996d235ac
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core/report.ts: 3758e6ea6f7453b23bb21682caa8828464add92d839c0cc8ae30fe46c4ca54fa
core/three-bridge.ts: 84d16dd2834354c360a85453499abfbc462cc616714fe7a04992ab18ab5037ff
core/units.ts: f5367c6aa2932463c90769fd0ac080e8a42aec71facf63ae32b0b08337020963
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core/write/3mf.ts: bf9afa50480b3cb71a2a768897b7dfd5347cafa6f4d3d59550c19edf4c80446a
core/write/gltf.ts: f650b65a62d81b2c617448053726e89b4a6e0beb27955dea8e1d413d4156c0a0
core/write/obj.ts: cb0b5571284c4fe9b217a82057fd0758d406bba0fd50815313fe4ca4d4f0248c
core/write/ply.ts: cd71a26936091a3619cd67f9dc609101aea8a1ee84bc7b5c7fafcc551a328797
core/write/step.ts: 05b888318d999a952aa5d9b2bddc47a79ef9d361b6828058df4b834c6ca886fd
core/write/stl.ts: bed130d62ee6a645d79ea8fdd70441e9abb0962354963798387601f458167323
core/write/usdz.ts: 4cd8d9bf0d1aa1755c374980e5fb863b3045979e8201f8d79fc8e0857c09e962
core/xml-namespaces.ts: 10820125e1331ee730f577319faea4f279f1dd5a7b29a4bb7ec56475b7a9b0d8
core/xml.ts: b1b9e09cda3013013956dd0c0ad915dc17d6ee499d9d0ec7cd6298aa5c625184
core/zip-strict.ts: 76bdd9135e717129fa130c5597134b96056e77dbe2f3b4ed493dacd98a1ba972
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