In the world of 3D modeling, one size doesn’t fit all. The models you produce can be stored in multiple 3D file types, such as step files, fbx, gltf, and obj formats. Knowing which format to use can make a major difference to 3D modeling projects. But if you’re struggling to tell 3D file formats apart, don’t worry. Read on to discover what roles each format plays, and where they should be used.

Get to know the major 3D file types

1. OBJ files: Where should they be used?

Created by Wavefront Technologies in the 1980s, OBJ (OBJect) files are the most commonly used 3D file types, so almost every model user should be familiar with them. Due to its age, this 3D file format is also the most basic and least detailed of the ones we’ll be looking at. However, OBJ files do still have their uses.

Pros

• OBJ will often be the default 3D file format for mainstream 3D modeling packages. That’s because the file type is the oldest of its kind, but also because it employs a flexible text-based language. This makes it a good exchange format as it can be easily exported and converted into other file types as needed.
• The OBJ file format supports unlimited colors and their simplicity also helps when carrying out tasks like 3D printing – which has ensured that this file type continues to be extremely relevant.
  

Cons

• OBJ models tend to be larger than other 3D file formats because they use plain text instead of binary to store information. This makes working with this 3D file format more laborious and time consuming. The extra time and size of OBJ models means that this file format has become less and less useful for high quality rendering and modeling.
• The OBJ file format cannot store information about animation or skins - just individual objects. Those are big drawbacks when creating graphics for games, adverts, or digital products.

How to use: The OBJ file format can be very useful when sharing files between different software packages, and these files can also be converted into other formats relatively easily. Think of it as a foundation on which to build more complex 3D creations. It is also one of the most popular formats for 3D printing operations such as rapid prototyping.

2. Where to use STEP file types

STEP (or STEP/STP) 3D file type is one of the most popular 3D file formats in the world of CAD modeling. Major CAD packages like Fusion, AutoCAD and OnShape rely on this 3D file format. So if you are modeling buildings or items like furniture via computer aided design, you may well need to deal with it.

STEP stands for Standard for the Exchange of Product Data, and this gives a clue about why this file format is important. It acts as a standardised file type to exchange files between CAD software and have even been given their own ISO classification (ISO 10303-21).

Pros

• STEP files are a reliable option when exchanging CAD files between different companies, freelancers, and internal departments. You can be totally sure that model files are interoperable, and that there won’t be any incompatibility issues.
• The way STEP files store data means that they are more precise than alternative file formats. The STEP file format uses mathematical functions called NURBS to store data, instead of using polygon based systems.
• The use of NURBS with this file format allows modelers to store extremely smooth and complex curves in a way that wouldn’t otherwise be possible. If you are creating precise models of sculptures, vehicles, or anything that incorporates curved surfaces, STEP will be one of the best 3D file formats.
  

Cons

• STEP files are somewhat limited and can only contain data about shapes. They don’t handle textures or colours. Similarly, unlike other file formats they won’t contain information about lighting setups or the cameras used to capture models.
• The reliance on NURBS also makes it impossible to directly render STEP files for 3D processing. Instead, you will need to convert NURBS into polygon-based file formats, creating extra work and potentially leading to distortions.
  

How to use: Use the STEP file format to model complex settings and objects where communicating shape and layouts is more important than creating the perfect texture. Use cases for this file format include architects, computer aided manufacturing and product design phases where technical data is all-important.

3. How to use the FBX file type

FBX is a hugely popular 3D file type that’s well-suited to high-end gaming rendering via systems like Unity. FBX is a shortened version of “Filmbox” - a film capture tool made by Kaydara which created the file format back in 2005. After a few changes of ownership, the FBX format is now owned by Autodesk, and is the 3D file format of choice for use with that company’s popular MotionBuilder capture tools.

Pros

• The FBX file format’s most important strength is versatility. FBX files can include a huge variety of data types. Models can be encoded with skins, animation data, bones, scene hierarchies, lighting, and material attributes.
• Models made via the FBX file format can be made much more complex than would otherwise be the case, featuring multiple topologies and supporting geometry like subdivided surfaces.
• The FBX file format works well with CAD files featuring NURBS coding, which is handy when transferring models from CAD designers to rendering operations.
• Despite adding extra features, FBX is a relatively fast file format. These files include digital information written in binary code, making them faster to read than older text-based alternatives.
• Binary data is also easy to integrate with official Software Development Kits used by 3D developers. So if you are reliant on SDKs during work flows, FBX files will make a lot of sense.
  

Cons

• FBX is a closed file format which only works with official SDKs, which could limit its use in some development contexts.
• While the format offers plenty of modeling features, some of the standards supported are becoming outdated. If you need to create realistic material properties like metal textures or complex anisotropic effects, FBX files will probably need to be reprocessed after rendering.
• Speed is fast but not as fast as a newer web-friendly file format like glTF.
  

How to use: The FBX file format is great for moving 3D models between popular editing tools and works well with older game dev systems like the Unity or Unreal engines. On the other hand, the format is being left behind by newer file types for high-end development and such files aren't ideal for web-based AR projects.

4. Using glTF 3D file types

glTF stands for GL Transmission Format. It competes with the FBX 3D file type for sophisticated modeling, but has other features which potentially make it more useful. This format is open source and was first released by the Khronos collective in 2015. This group continues to develop and manage the standard as an open file format, ensuring that it is updated and relevant to the needs of major 3D model creators.

The format initially arose to fill a huge gap in the market. Instead of processing heavy, bloated 3D models, the designers of glTF sought to create something similar to JPEG files. The idea was to keep model files small and easy to transmit via the web.

Pros

• glTF was designed to maximize web browser compatibility – something that 3D file formats like FBX lack. So it's become a go-to for businesses blending 3D models and the World Wide Web.
• The format also has speed advantages over other 3D file formats. Model files can be x5 smaller and can be read as much as 10 times faster than OBJ files. The use of topology meshes to store product model data also gives glTF speed advantages compared with FDX files, which need to be translated when they are integrated into 3D engines.
• glTF can also handle animation with ease - a handy feature for AR developers to exploit.
• The ability to read glTF files directly into engines also makes the format ideal for web-based augmented reality applications.
  

Cons

• Image quality can be an issue. glTF is not the ideal format for high-end game development or special effects in the film industry. The models it stores are comparable to FBX in their quality and complexity, and lack key features like shader networks.
• glTF is not optimized (yet) for 3D printing, so conversion to the STL file format or OBJ may be needed.
  

How to use: glTF works well for web-based AR. In fact, web giants like Facebook and Google have adopted the format for their AR services due to its efficient design and sheer speed.

If you are reading product models into catalogues or creating AR apps to showcase your services, delivering content via glTF is also likely to be the best option. Examples could include fashion labels, home furnishing retailers, and much more.

5. Where to use usdz/usd files

USD and USDZ files were initially created by the animated movie studio Pixar to handle their popular CGI based films. But the format went beyond filmmaking when Apple embraced it, making it a vital tool for AR developers on iPhones and iPads.

USD stands for Universal Scene Distribution (the “z” denotes that the files have been zipped) and these files have a lot of strengths for users to think about.

Pros

• Technically, the USD 3D file type excels. Models can be encoded with skins, lighting, bones, blend shapes, animations, different materials, and scene hierarchies. The range of features available from USD puts it on the cutting edge of 3D modeling. If you want to create ultra-realistic 3D with lifelike materials and complex lighting, this is the format to use.
• You can use USD to store images with multiple topologies, allowing for the creation of surfaces that look more detailed and lighting conditions that create the perfect atmosphere.
• USD is also seriously fast during the processing phase, thanks to its efficient binary coding.
  

Cons

• USD’s modernity could be a drawback. The format is not backwards compatible with older standards like the OBJ format or FDX files, and only works with software programs supplied by Apple. Without alternative software, the models produced only work effectively on Apple devices.
• Files created using this format also come up big. USD files are bloated compared to web-friendly glTF alternatives which use compression cleverly to retain geometric accuracy and maximize speed.

How to use: The best application for USB/USBZ 3D model files is AR development on iOS platforms. If you want to create virtual catalogues or immersive experiences for iPhone users, you may find that Apple’s tools are the best way to do so. And if you have the resources for Pixar-style movie industry projects, you can benefit from the technical advantages that the format delivers.

Why are there so many different file formats in 3D? 

As you can probably tell, there are plenty of options when choosing a 3D file format. Unlike photography, which tends to feature standardized file formats, 3D modeling has become more diverse and fragmented. But why is that the case?

In practice, different industries tend to rely on different formats. For instance, 3D printing could use OBJ or STL files, while game devs might prefer the FBX format and iOS devs would probably prefer formats like USD.

That’s generally due to reliance on different software packages and the demands of various sectors. For example, turning CAD diagrams into 3D models or converting photographs into images for use on iOS devices requires different software. So different 3D file types have evolved to cater for the different tools.

At the same time, CAD and 3D modeling software developers have created their own standards to protect their intellectual property and maximize market share. This has created a chaotic situation featuring literally hundreds of file types, stretching way beyond the most popular formats we’ve talked about already.

This can lead to problems when models need to be shared across multiple projects. Models might need to be 3D printed, included in web-based AR apps, added to high quality animations, or even used in game environments. Each purpose will probably need the right format and software, requiring time-consuming conversion and retouching processes.

However, a solution may be near thanks to an organization called the Khronos Group.

Khronos is a non-profit alliance of over 170 companies and other organizations which seeks to standardize 3D file types. The aim is to make AR and VR development simpler and more streamlined, an area where the glTF file format mentioned above is making rapid progress.

With major brands like Sun Microsystems, Intel, AMD, Google, and Sony all on board, the project has powerful backers. CGTrader has also signed up, putting us at the heart of the standardization process.

Find the Perfect 3D file type for your modeling project

In the past, 3D modeling has been a complex process with a dizzying array of file types. Each format has its specific role, as well as unique pros and cons. As we’ve seen, there are still uses for older standards like OBJ, as well as popular formats like FBX, glTF, STEP files, and USD.

But that’s changing as the industry matures. These days, 3D modeling for app and game development is becoming simpler and cheaper. Standardized format types like glTF are powering the growth of AR experiences, making it possible to create product viewers, interactive stores, and a host of other next gen retail experiences.

CGTrader is ready to become your 3D modeling partner. Whatever 3D file type you use, we can find an efficient, affordable, and effective way to turn 3D models into real world sales. Get in touch today and explore our modeling services.