STL (STereoLithography): Format for Printable 3D Files
STL is a 3D file format. It is used to store uncolored mesh. It was initially developed by 3D Systems.
A triangular mesh as stored in an STL file
Information about Storage
An STL file describes mesh surfaces as lists of geometric features.
A solid is composed of triangular faces, which are composed
of a normal and 3 vertices described by their coordinates.
The normal is optional and can be used to determine the inside
of the mesh. In case normals are not properly set they
can be computed using the face vertices. If it is not possible
to determine the inside of a mesh, it must be
Information can be stored either in plain text or binary form,
the later is used more often as it is a more efficient
Vertex position are saved without any unit. The unit can be
set on Sculpteo website after it is uploaded.
Description of the STL file format
Here is a non-exhaustive list of software supporting STL.
Direct file exports:
Exports after tessellation:
Tessellation is the phase used, where the geometry is transformed
into triangles in order to be saved. This phase may alter the
original mesh if the resolution is too big.
Difference between original surface and tessellated surface
When to use STL Format
Compact and simple file format. The file format only specify
the bare minimum to describe 3D model which makes it easy
to use. Like other mesh file format (obj, wrl, ply, ...)
there is no need to go through a tessellation phase which
alters the original mesh to obtain a printable file.
- Supported by multiple 3D modeling softwares and 3D printers .
Discards connectivity information, but most 3D softwares can
infer it, Sculpteo tools will recompute it when the model
- Color support is not standard and often not supported. for multicolored mesh you must choose another format from this list .
STL files are good choice to upload a single color model on Sculpteo website as the color can be chosen afterwards.