![Continued…
The binary STL file format
If the tessellation involves many small triangles, the ASCII STL file can
become huge. This is why a more compact binary version exists.
UINT8[80] – Header
UINT32 – Number of triangles
foreach triangle
REAL32[3] – Normal vector
REAL32[3] – Vertex 1
REAL32[3] – Vertex 2
REAL32[3] – Vertex 3
UINT16 – Attribute byte count
end
The binary STL file starts with a 80
character header.
Each triangle is represented by twelve 32-
bit floating point numbers.
Just like the ASCII STL file, 3 numbers are
for the 3D Cartesian co-ordinates of the
normal to the triangle.
The remaining 9 numbers are for the
coordinates of the vertices (three each).](https://image.slidesharecdn.com/amfileformats-231018180721-d45b5064/85/AM-file-formats-pdf-7-320.jpg)
AM file formats.pdf
- 1. Contents Introduction STL file format Advantages and limitations of STL file formats New AM file formats AMF file format Conclusion References
- 2. Introduction A 3D printer file is a way to store information about 3D model. All 3D printer files contain the data about the shape of 3D model, their geometry. The 3D printer file formats and tools are tightly coupled. There are several file formats that can hold such data. Examples include STL, OBJ, 3MF, VRML etc. STL is the most commonly used 3D printer file format across the globe.
- 3. STL file format The first 3D printer was invented by Chuck Hull in 1987 at 3D Systems. The same guy was behind the STL file format. It is a file type created for rapid prototyping by 3D Systems. It was very quickly and easily adapted by all the 3D modeling software, slicers, and 3D printers. It stands for STereoLithography or Standard Triangle Language or Standard Tessellation Source - https://all3dp.com/what-is-stl-file-format- extension-3d-printing/#pointten
- 4. How does the STL file format store a 3D model? Tessellation is the process of tiling a surface with one or more geometric shapes. Exploiting tessellation to encode surface geometry : store information about the facets in a file. Tessellation Paintings Tessellation of cube and sphere Source - https://all3dp.com/what-is-stl-file-format-extension-3d-printing/#pointten
- 5. How does an STL file store information about facets? ASCII encoding Binary encoding In both formats, the following information of each triangle is stored: I. The coordinates of the vertices. II. The components of the unit normal vector to the triangle. Source - https://i.all3dp.com/wp- content/uploads/2016/11/27015532/vertices- and-normal.gif
- 6. Continued… The ASCII STL file format The file continues with information about the covering triangles. solid <name> facet normal nx ny nz outer loop vertex v1x v1y v1z vertex v2x v2y v2z vertex v3x v3y v3z Endloop endfacet endsolid <name> —The ASCII STL file starts with the mandatory line —n is the normal to the triangle and v1, v2 and v3 are the vertices of the triangle. Co- ordinate values are represented as a floating point number with sign-mantissa-e-sign- exponent format, e.g., “3.245000e-002”. —The file ends with the mandatory line
- 7. Continued… The binary STL file format If the tessellation involves many small triangles, the ASCII STL file can become huge. This is why a more compact binary version exists. UINT8[80] – Header UINT32 – Number of triangles foreach triangle REAL32[3] – Normal vector REAL32[3] – Vertex 1 REAL32[3] – Vertex 2 REAL32[3] – Vertex 3 UINT16 – Attribute byte count end The binary STL file starts with a 80 character header. Each triangle is represented by twelve 32- bit floating point numbers. Just like the ASCII STL file, 3 numbers are for the 3D Cartesian co-ordinates of the normal to the triangle. The remaining 9 numbers are for the coordinates of the vertices (three each).
- 8. Special rules for the STL format The vertex rule The vertex rule states that each triangle must share two vertices with its neighboring triangles. The orientation rule The orientation rule says that the orientation of the facet must be specified in two ways. Source - https://all3dp.com/what-is-stl-file-format- extension-3d-printing/#pointten
- 9. How is an STL file 3D printed? For 3D printing, the STL file has to be opened in a dedicated slicer like Cura or Simplify3D. The slicer chops up STL file into hundreds (or thousands) of flat horizontal layers. All of this information is then bundled up into a GCode file. Slicer settings do have an impact the quality of print. The next stage is for those separate two-dimensional layers to be reassembled as a three-dimensional Source - https://i.all3dp.com/wp- content/uploads/2016/02/27113945/Best-3D-printing- software-for-beginners-Cura.png
- 10. Optimizing an STL file for best 3D printing performance The 3D printer will print the object with the same coarseness as specified by the STL file. As the size of the triangle decreases, the number of triangles needed to cover the surface also increases which leads to gigantic file size. It is therefore very important to find the right balance between file size and print quality. Source - https://i.all3dp.com/wp- content/uploads/2016/11/27020134/increasin g-resolution.png
- 11. Continued… Let’s dig into the most important settings and find out their optimum values. Chordal height or tolerance Source - https://i.all3dp.com/wp- content/uploads/2016/11/27020138/chord-height.png Angular deviation or angular tolerance Source - https://i.all3dp.com/wp- content/uploads/2016/11/27020137/angular- tolerance.png 0.01-0.001 mm
- 12. STL file format : Advantages Simple and old 3D printer file format. Flexibility more facets for better resolution. Easy to handle and transfer. de facto standard for 3D printing.
- 13. STL file format : Disadvantages STL 3D printer file format stores a lot of redundant information. Table for ~63,000 triangular facets Slow and error-prone. Incapable of storing color, material and texture information. 3D file format s PLY (binary ) PLY (ASCII) OBJ (ASCII) VRML (ASCII) STL (binary ) STL (ASCII) Size(M b) 1.1 2 2 2.7 3 11
- 14. New file formats OBJ file format AMF file format 3MF file format VRML file format
- 15. AMF file format (.AMF) The AMF (STL 2.0) 3D printer file format was developed by ASTM/ISO in 2011 as a replacement for the STL file format. The aim was to address many of the shortcomings of the STL 3D printer file formats. AMF addresses the issues in STL by using an XML format with a hierarchy of five elements viz. object, material, texture, constellation, and metadata. As of today, Solidworks and the Autodesk suite supports it. Among Slicers, Cura has support for AMF. Source - https://i.all3dp.com/wp- content/uploads/2017/10/26234325/AM F-Logo.png
- 16. AMF 3D printer file format features It allows curved triangles in addition to planar straight triangles – and it makes all the difference. It has support for all the modern requirements of 3D printing like RGBA colors, sub-structures, microstructures, porous materials. Source - https://i.all3dp.com/wp- content/uploads/2017/10/26234321/Curved _triangle.png Source - https://i.all3dp.com/wp- content/uploads/2017/10/26234317/dual_material.jpg
- 17. Continued… The “constellation” feature allows multiple objects to be arranged within the file, specifying their location and orientation. Source - https://i.all3dp.com/wp- content/uploads/2017/10/26234309/multiple_object_ same_model.jpeg
- 18. Basic file structure Within the AMF brackets, there are five top level elements <amf> <object> <material> <texture> <constellation> <metadata> </amf>
- 19. How to write the AMF file format ? Source - https://www.nist.gov/sites/default/files/documents/2017/04/28/Lip son-Cornell-NIST-AMF.pdf
- 22. Comparision between STL and AMF file formats Source - https://www.nist.gov/sites/default/files/documents/2017/04/28/Lipson- Cornell-NIST-AMF.pdf
- 23. Conclusion At this point of time, STL, OBJ, AMF, and 3MF seem to be the most important 3D printer file formats. They all have their own strengths, weaknesses and have varying levels of compatibility with 3D printing software and hardware. It is imperative to know and understand the key differences between these formats. Toolchain Production efficiency The quality of prints.
- 24. References Sculpteo (https://www.sculpteo.com/blog/2018/10/17/top-4-of-the-best-3d- printer-file-formats/) All3dp (https://all3dp.com/3d-printing-file-formats/) NIH 3DP Print Exchange (https://3dprint.nih.gov/faqs/1781) Wikipedia (https://en.wikipedia.org/wiki/3D_Manufacturing_Format) Lipson-Cornell-NIST-AMF (https://www.nist.gov/sites/default/files/documents/2017/04/28/Lipson- Cornell-NIST-AMF.pdf)
- 25. Thank You !!