Demystifying 3D File Formats For 3D Commerce And More
With hundreds of 3D file formats available it’s hard to know which 3D file format you should use or how it compares to others. We take the guesswork out of 3D file formats for you below by highlighting the top 3D file formats for 3D web and AR and their best use cases.
3D file format explained
What is a 3D file? Simply put, a 3D file format stores information about 3D models. This includes geometry (it’s shape), appearance (it’s color, texture, and/or materials), scene (the position of a light source, camera or other objects around the 3D model) and animations (how the 3D object moves, including skeletal information and morphs).
3D models store the 3D information as either plain text or binary data for the 3D model.
There are literally hundreds of 3D file types available because each 3D software program has its own file type that is optimized for that particular software. For example, Blender has BLEND, AutoCAD has DWG, Clo has .zprj, and Browzwear has .bw, just to name a few.
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Proprietary 3D file formats
The problem that proprietary 3D file formats cause, is that almost all of these formats are just that — proprietary — meaning they can’t be used in other programs.
Imagine you are using Blender and your 3D fashion designer colleague is using Browzwear. You have a 3D model you need to share with your colleague but, because you are both dealing with different proprietary 3D file formats, the two of you cannot work on the same 3D model. Blend can not be imported into Browzwear and .bw can not be imported into Blender.
What’s the solution? Neutral 3D file formats or FBX. While FBX is a proprietary format, many software programs use it as an exchange format.
Neutral 3D file formats
To solve this problem of interoperability, neutral (or open source) 3D file formats were developed. These neutral formats serve as intermediate formats between two proprietary formats.
As you can imagine, these neutral formats are highly popular among designers and 3D artists. If you want to share your 3D model with a peer who isn’t using your same 3D design program, you can convert your file into a neutral 3D file format and share it with your peer to import into their 3D software program. Using our example above, if you export an FBX from Browzwear you can import that into Blender. With minimal effort, you can continue to use different software while collaborating with others.
Common 3D file formats
Most 3D modeling software platforms now support neutral 3D formats, however issues can arise if you convert a 3D file too many times. Therefore, you still need to choose the right neutral 3d format from the beginning to avoid unnecessary conversions.
To help you find the perfect 3D format for your needs, here are the eight most common 3D file formats and why they should be on your radar.
gLTF/GLB
gLTF/GLB is a neutral, open source format. The Khronos Group created this format for 3D web, AR, VR, Games and 3D advertising. It’s the first really well-defined standard for 3D. This file format supports geometry, materials, textures, colors, and animations. This includes PBR (Physical Based Rendering), so shadows and light will appear more realistic.
gLTF is based on JSON, so it stores some data in external files like textures (JPEG or PNG), shaders (GLSL), or geometry and animation data (BIN). GLB files store all this data internally. The Khronos groups is continually improving and updating this file format. It is quickly becoming the standard for 3D shopping.
FBX
FBX is a proprietary 3D file format. Kardara originally developed this format. AutoDesk then purchased them in 2006 and continued supporting FBX. It is widely used in the film and video game industry. It supports geometry, appearance (color and texture), as well as animations (skeletal and morphs). FBX is most popular for animation and is used as an exchange format between different programs like Maya, 3DSMax, AutoCAD, Roman’s CAD, and others.
OBJ
OBJ is a neutral 3D format when used as an ASCII variant. However, when used as a binary variant, it is proprietary. 3D printing, graphics, and 3D scanning all use this file format thanks in part to its ability to store geometry as well as color and texture information. This file format stores color and texture information in a separate file with extension .MTL. OBJ does not support animations but is one of the most popular interchange formats for 3D graphics.
USDZ/USD
Apple and Pixar developed USDZ/USD. It is a proprietary 3D file format and mainly used for Augmented Reality on iOS devices. This file format is most popular for 3D commerce since you can do placement and try-on of 3D models on iPhones with this format.
STL
This 3D file format is most popular for 3D printing. It is a neutral 3D file format. This file format only stores geometry information.
STEP (.STP)
The engineering and defense industry use STEP. It is a neutral 3D file format. This file format can store all geometry including topology and geometrical tolerances, material types, textures, and other complex product data.
COLLADE
The Khronos Group also created COLLADE, another neutral 3D file format. This file format stores geometry, appearance, scene, and animations. It also is one of the few formats that supports physics and kinematics. While once heavily used, COLLADE has become less popular over time due to its failure to keep up with new technology. The Khronos Group opted not to update this format, but instead created the new format GLTF.
Which 3D file format to choose
What 3D file format should you choose for exporting and sharing your 3D models?
While each modeling software program provides you with the opportunity to export your model into many different 3D file formats, the option you choose depends on the end use case.
Before making a decision on which 3D file format you should choose, we recommend asking yourself the following important questions:
- Which features do I need? Depending on which industry you are in, you might want different sets of features in your ideal 3D file format.
- Which software am I going to use? Not all software support importing and exporting of all 3D file formats, so you need to choose a file format supported by yours.
- Which software do my collaborators use? The file format that you choose needs to work well with both your projects, but also with your collaborator’s as well.
- What is the end use case of the 3D file? For example, 3D web or AR experiences require GLB/GLTF and USDZ/USD.
Conclusion
As you can see, there are a variety of 3D file formats to choose from. Educating yourself on the differing options — and their capabilities — will help you best determine which format is best for you. It also will help you determine which option will make your life easier and save you time (and money) as you partake in collaborations.
If you plan on using 3D for advertising and ecommerce, each platform has their own specific 3D file format requirements. VNTANA created this 3D Commerce & Advertising File Format Guide so you know what is required to distribute 3D files everywhere.
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