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February 18, 2023

Comparing the Most Popular 3D Printing File Formats: OBJ, STL, AMF, and 3MF

3D printers construct parts by building them layer by layer. After a 3D model is created and saved in a compatible file format, it must be sent to a slicing software that divides the solid model into many thin horizontal layers. The slicing software analyzes the layers and creates G-Code. This is a set of instructions for the 3D printer on how to move to produce the final object. Some 3D printers come with their own slicing software. That way the model can be sent directly in the proper file format.

The information stored in the CAD file is crucial for successful printing. The file format determines the information contained in the file and is necessary to generate the appropriate machine code. There are specific types of information, such as geometry, texture, color, and material, that are needed for the printing process. Standard 3D CAD file formats, such as STEP, IPT, and SLDPRT, do not always contain this information or are not coded for 3D printing. Thus, we now need file formats specifically for 3D printing. The most commonly used 3D printing file formats today are STL, OBJ, AMF, and 3MF.

Key Information: STL

STL (Standard Tessellation Language) is considered to be the standard in 3D printing, having been created in 1987 by the inventor of 3D printing, Chuck Hull. Its long history makes it compatible with most 3D CAD software and 3D printing hardware and software.

It stores geometry data using tessellation, which is the process of covering a surface with triangles to create a 3D model. However, it only stores geometry data and doesn't include information such as color, texture, and material. The number of triangles used to create a model determines the level of detail, and the more triangles used, the larger the file size.

An important feature of STL is its use of tessellations to represent geometry. This involves covering a surface with a pattern of shapes. In an STL file, a 3D object's shape is represented by a multitude of triangles that make up its surface.

The more complex a surface, the more triangles are needed to accurately represent it. However, a high number of triangles results in a larger file size.

Another defining aspect of STL is that it only contains geometry information. It does not include details such as color, texture, or material, which were not a concern in the past when 3D printers could only produce single-color, single-material prints. While this may still suffice for basic prototypes, advancements in multi-color and multi-material 3D printing may lead to the eventual phasing out of the STL format as it becomes insufficient for fully functional, ready-to-use objects.
3D Принтиране и файлови формати

Advantages:

- Compatible with a wide range of hardware and software in the 3D printing industry.
- STL format is the most commonly used and shared file format for 3D printing. There are millions of STL models available online for download.
- Has the longest history and has been researched and used since its creation in 1987.

Disadvantages:

- The STL format can only store geometry data, leaving out information such as color, texture, and material.
- The level of detail in STL files is limited, as curved surfaces are represented using a series of small triangles.
- The higher the accuracy of the STL file, the larger it will be.
- There may be gaps and overlapping triangles in the tessellation, which can make the file format error-prone.
- The STL format does not specify the scale or units used in the model.
3D Принтиране и файлови формати

Key Information: OBJ

The OBJ file format was created by WaveFront Technologies and was initially used in the world of graphic design. Its function was exchanging information between different software programs. Over time, as 3D printing technology has advanced to include multi-color and multi-material capabilities, the OBJ format has also become widely used in the 3D printing industry.

The OBJ file format is widely popular, taking second place after STL, in the world of 3D printing. Unlike STL, OBJ files can store not only geometry data but also information about color, texture, and material. This information is stored in a separate MTL (Material Template) file. To print with color, the OBJ file must be accompanied by its corresponding MTL file.

One of the key benefits of the OBJ file format is the ability to choose how the geometry of your model is encoded. OBJ files support the use of various shapes, such as polygons and quadrilaterals, in addition to triangles, to create tessellations. Advanced and more precise methods, such as free-form curves and surfaces, can also be employed in OBJ files. This allows for greater accuracy in the storage of 3D models.

Advantages:

- Allows for greater accuracy in the representation of 3D models.
- The format can store data about not just the geometry of a model but also its color, texture, and material properties.

Disadvantages:

- Not as widely used as the STL file format. This means it may have limited compatibility with some hardware and software used in 3D printing.
- The large amount of data stored in OBJ files can make sharing or editing time-consuming.
- Color and texture information is stored in a separate MTL file, which must be included in order to accurately print a model in full color.

Key Information: AMF

AMF is a more advanced file format that can store a greater level of detail and information than STL. This includes color and texture information, which is lacking in STL. In addition, AMF supports more advanced geometry encodings such as free-form curves and surfaces, and it provides a way to specify the material properties of the object being printed.

Another advantage of AMF is that it provides a more efficient method for storing data, which results in smaller file sizes. This allows for faster data transfer and easier sharing and editing of models. AMF is also designed to be flexible, allowing for updates and new features to be added in the future.
However, despite its advantages, AMF is not as widely used as STL and is supported by fewer software and hardware platforms. This means that compatibility and ease of use can be a concern for some users.

In conclusion, AMF is a modern, advanced file format for 3D printing that offers a number of benefits over STL. However, its limited compatibility and reduced popularity in the industry may make it less accessible for some users.
Файлови формати за 3D принтиране

Advantages:

- Can store all possible data and metadata about a model including geometry, color, texture, and material information.
- Supports the specification of scale in various units, providing greater accuracy and control over the final product.
- Low error rate due to its advanced encoding methods, reducing the need for file repairs.
- Compact file size, making sharing and editing easier and more efficient.

Disadvantages:

- Less popular and not as widely used as STL or OBJ, leading to limited compatibility with some hardware and software platforms in the 3D printing industry.
- The adoption of this format may require a learning curve for users who are used to STL or OBJ file formats.
3D Принтиране и файлови формати

Key Information: 3MF

The 3MF consortium, consisting of prominent companies in the 3D printing industry such as Autodesk, 3D Systems, Stratasys, HP, and Microsoft, was formed to address the limitations and slow adoption of the AMF file format. The consortium developed the 3MF 3D printing file format, which is similar to AMF but has gained wider acceptance.
The widespread acceptance of the 3MF 3D printing file format is due to the industry presence and large customer base of the 3MF consortium, as well as the capabilities of the file format itself.

The 3MF file format features all the technical characteristics of AMF, such as the use of curved triangular tessellations for encoding geometry and the ability to store color, texture, material, and orientation information with high precision.
The 3MF 3D printing file format stores data in a readable XML format, making it easier for development and editing. These files are known for their low error rates and are regarded as immediately ready for printing, which is a highly valued feature in the 3D printing industry.

Advantages:

- Relatively well-known and has compatibility with many different companies.
- Accurately encodes geometric information and can store all relevant details and properties of a 3D model in a single file.

Disadvantages:

- Possibility of proprietary ownership.

In Conclusion

In summary, the STL file format is a good choice for basic, single-color prototypes. If you need to print simple objects in color, then the OBJ file format is a better option. However, keep in mind that the texture and color data are stored in separate files, making sharing OBJ files more complicated. Meanwhile, the 3MF and AMF 3D printing file formats offer the most advanced capabilities, including the ability to store all information related to a model, including color, texture, material, and orientation data. These formats are ideal for complex, multi-part, multi-color, and multi-material objects and make file sharing much easier thanks to their compact, compressed file format. If you have compatible software, the AMF format may be the way to go. Otherwise, the more widely accepted 3MF format is likely to be compatible with more software.

For Further Information and Inquiries

For more information about the right file format for your particular project, send us a drawing, sketch, or image at sales@solidfill.com.
Have a look at our '3D Printing' page and the 'File Formats' section in particular. Also, make sure you follow us on Facebook or contact us if you have any questions. 

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