What is the HSF file format?
An .hsf file is a 3D visualization stream produced by the HOOPS Visualize SDK from Tech Soft 3D. It encodes 3D geometry, product structure, materials, lights, cameras, and named views in a compact sequential stream of typed opcodes, making it well-suited for real-time streaming of large CAD and industrial models to web and desktop viewers.
Every .hsf file opens with a human-readable 5-byte version tag - HSF V followed by a numeric version string (for example HSF V1600) - that identifies the producing HOOPS version and guarantees backward-compatible decoding via the HOOPS Visualize SDK. Geometry is compressed using LZ for general data, plus geometry-specific techniques: quantized normals, delta-coded vertices, and LOD (Level of Detail) shell representations that scale well for large assemblies.
The format supports a rich set of primitives: polygon shells, polylines, NURBS surfaces, Unicode text, vertex colors, texture mapping, and user-defined fonts. It is widely embedded in CAD viewers, digital twin platforms, and PLM tools through the HOOPS SDK. Tech Soft 3D spun off from Autodesk in 1996.
For long-term archival or PDF 3D embedding, the ISO-standardized .prc format is generally preferred. HSF remains the format of choice for high-performance real-time visualization pipelines.
- The version number after
HSF Vencodes the HOOPS release that produced the file. - Okino PolyTrans and SolidWorks eDrawings support
.hsfviewing and export. - The format runs natively on Windows, Linux, macOS, iOS, and Android via the SDK.
Security & safety
RISK: LOWHSF files contain 3D geometry and attributes with no scripting or macro capability. No known security vulnerabilities.
Format details
in a nutshellPrograms that open HSF files
Windows3 apps
SolidWorks eDrawings
Free File > Open, select the HSF file. eDrawings displays 3D geometry with pan/zoom/rotate.
Okino PolyTrans
Paid Open PolyTrans, File > Open, choose HSF; supports import and export for format conversion. 
macOS1 app
Technical details
deep spec| Magic bytes | 48 53 46 20 56 ("HSF V") at offset 0 |
| Version encoding | Numeric string following "HSF V" header, e.g. HSF V1600 |
| Container | Proprietary opcode-based sequential stream (HOOPS Stream Format) |
| Byte order | Little-endian |
| Compression | LZ (general) plus quantized normals, delta-coded vertices, LOD shell representations |
| Typical file size | 100 KB - 500 MB (scales with model complexity) |
| Geometry primitives | Polygon shells, polylines, NURBS surfaces, Unicode text, vertex colors, texture mapping |
| Color depth | 24-bit RGB with optional per-vertex or per-surface alpha |
| Product structure | Assembly tree, named views, lights, cameras, and user-defined fonts encoded |
| Backward compatibility | HOOPS Visualize SDK guarantees backward-compatible reading across all versions |
| Associated OS | Windows, Linux, macOS, iOS, Android |
| Archival alternative | .prc (ISO 14739-1) preferred for archival and PDF 3D embedding |
| Developer | Tech Soft 3D (spun off from Autodesk in 1996) |
| Released | late 1990s (HOOPS 3.x era, Tech Soft 3D) |
| Latest version | HOOPS Visualize 2024 (HSF spec remains backward-compatible) |
| Specification | docs.techsoft3d.com |
HSF conversions
Community Q&A
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