STL and OBJ: Similarities and Differences

There are many different types of 3D printing file formats, and it can be confusing to understand the difference between them. This blog post will explain the difference between STL and OBJ files. STL files are used for 3D printing, while OBJ files are used for rendering. OBJ files are more complex than STL files but have more features. If you are unsure which file format to use, STL is a good choice for 3D printing. What makes STL and OBJ file different from one another? Continue reading to learn more about the differences between the STL and OBJ file formats and find out which will suit your needs best.

What is STL?

The 3D file format used in 3D printing is STL (Standard Tessellation Language). The STL file format is still the most popular and is considered the industry standard for 3D printing. This is because STL, which has been around for so long, is compatible with most 3D CAD software and other software and hardware used in 3D printing. One of its key features is that STL uses tessellations to save geometry. The act of covering (tiling) a surface with numerous geometric shapes without any gaps or overlaps is known as tessellation. A 3D model's geometry is represented in an STL file by many triangles covering the model's surfaces.

It takes a lot of arbitrarily small triangles to cover curved surfaces completely. However, the file size increases with the number of triangles used in a model. Another distinguishing feature is that the STL 3D printing file format only stores geometry data. A model's color, texture, and material-related information are not included. In the past, printers could only print on one material and one color at a time. It might not even be an issue if you only need a straightforward prototype. However, the STL file format might soon be obsolete due to 3D printing advancements like multi-color and multi-material printing and the use of 3D printing to create fully functional, ready-to-use objects.

Advantages of STL Files

• Easy to use, quick, and simple.
• Little-sized files.
• Flexible for a range of projects.

Disadvantages of STL Files

• Minimal resolution.
• The 3D model's geometry is the only information stored.
• 3D models encoded in STL are difficult to modify.

What is OBJ?

The OBJ file format was created by WaveFront Technologies and was initially used in graphics design as a neutral interchange file format. Later, the 3D printing industry adopted the file format with the advancement of multicolor and multi-material printing. OBJ is only second to STL in terms of popularity. However, OBJ can store geometry, texture, color, and material data, whereas STL only stores geometry-related information. A separate companion MTL is used to store color information (Material Template). An OBJ file must be shared with its corresponding MTL file to print in color.

You can select how your model's geometry is encoded, which is another important feature of the OBJ 3D printing file format. Not only triangles but also other shapes like polygons and quadrilaterals can be used to make tessellations. Additionally, you can use more sophisticated and exact techniques like free-form curves and surfaces. These enable far more accurate model storing in OBJ files.

Advantages of OBJ Files

• Awesome for group projects.
• The original model's mesh and texture data are preserved.
• Due to the resolution and color data preservation, it is ideal for games and other animations.

Disadvantages of OBJ Files

• It is not very user-friendly and can be a little challenging to use.
• Rendering takes a long time.
• A large file size.

STL Vs. OBJ

Points	STL	OBJ
Overview	In STL files, objects are represented by groups of vertices connected by edges to form triangular faces.	Unlike STL files, which only support a list of vertices connected by edges, OBJ files support polygonal faces, allowing for a more accurate representation of the original geometry.
Model Structure	The STL format is sufficient for simple geometry because it depicts an object's surface as a mesh made entirely of triangles. The file size grows almost exponentially due to the higher model fidelity requiring more triangles. It will nonetheless be an approximation even at the highest resolution.	Precise surface encoding is supported by OBJ, which includes multiple types of polygons in a single file. NURBS patches enable a much smoother and more accurate representation and can also be used to define the surfaces instead of facets.
Colour and Texture	STL is unable to store any data about these properties. As a result, it's not the best format for applications that only involve graphics or those that involve 3D printing in multiple colors or materials.	At this point, OBJ excels and is especially beneficial for 3D scanning applications. This format allows for the incorporation of real photographic data in a two-dimensional image that surrounds and extends through the model and is typically stored in a separate image file.
Software Compatibility	For the majority, if not all, of 3D slicers used in desktop 3D printing, STL is the accepted format. It is also the most popular format for sharing 3D printing design files because of its ease of use and small file size.	Popular 3D printing slicers like Cura and Simplify 3D for FDM, ChiTuBox and PrusaSlicer for resin printing support OBJ. However, the format is more adaptable than STL because it's regularly used for tasks other than 3D printing. For instance, OBJ files are commonly used in game development. Therefore, the format is broadly supported by graphics and animation software.
Uses	Exclusive to 3D printing and quick model sharing. STL files are considerably simpler and more compact. Almost all slicer software platforms can open STL files, and some versions are only meant to open STL files. Put your models on a public website, like Thingiverse. Anyone can download and print your model using an STL file, but changing it will be extremely difficult. Naturally, this is predicated on the assumption that you don't want anyone to alter your model.	Sharing of collaborative work models. An OBJ file makes it possible for others-including the general public-to modify or improve your original model. The best part is that OBJ files work with various CAD software programs. If the model needs to be published in a format that keeps its original mesh and texture information, use OBJ files. For high-resolution or full-color 3D printing, texture data preservation can be essential and flexible. Preserving a model for future alterations. You must store it in the OBJ file format if you're working on a 3D modeling project that you anticipate modifying in the future.

The most popular 3D file formats today are STL and OBJ. You can convert STL files to OBJ using your preferred CAD software or an online converter. Most CAD software and slicers typically support the OBJ and STL file types, often used for various 3D printing projects. It's common and straightforward to switch between STL and OBJ file types online using converters like MeshConvert. However, converting these files within your preferred CAD software can also be a simple procedure, depending on the type of programming. While OBJ is renowned for its adaptability, skill with color and texture preservation, and collaborative projects, STL is renowned for its speed, compatibility, and simplicity of use.

Conclusion

The STL file format is probably well known nowadays to most people interested in 3D printing. After all, STL encodes the vast majority of the free 3D models that are accessible online. Although the small file size and relative ease of use make STL files ideal for quick distribution of models, their ability to store detailed information with high resolution is severely constrained. We don't discount the value of STL files. 3D printing has boomed due to the shareability of STL models. However, we believe the future of 3D printing lies with OBJ files. OBJ files offer a chance to investigate full-color 3D printing because they can preserve texture data and precise mesh encoding. The OBJ file format is the only option for those who want to edit or build their own 3D models.

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