A file with the .aoi extension is used by Art of Illusion, a free, open-source 3D modeling and animation program started by Peter Eastman. This type of file contains a complete 3D scene, including models, materials, textures, lights, cameras, and animation data, so that Art of Illusion can reopen the project exactly as it was last saved. Rather than embedding all image data directly, many AOI scenes reference external texture images, which means the original folder structure often matters when moving projects between systems. Because .aoi is a program-specific 3D format and not a general exchange format like OBJ or FBX, most other applications cannot open it directly. If you discover an .aoi file outside of an Art of Illusion setup, you can use FileMagic to identify it as an Art of Illusion 3D scene file and, where supported, preview the contents before deciding whether to ask for an exported model in a more common format.

A three-dimensional image file is a special kind of file that describes a 3D object so that 3D applications can render it, rotate it, and in many cases animate it. This makes it very different from ordinary image files such as JPG or PNG, which are limited to 2D pixels. A 3D file goes beyond that: it can say "this vertex sits at this position", "this point connects to that one to make a surface", and "this part should use this material or texture". Because it carries structural information, 3D image files are commonly used in game development, animation, visualization, engineering, training content, and modern AR/VR.

Under the hood, there is usually a description of the object’s shape, often called the geometry or mesh. This consists of points in 3D space and the faces that connect them, which give the object its form. On top of the shape, many 3D files also reference the appearance of the object, such as materials and textures, so the program knows whether a surface should look metallic, matte, see-through, or painted. Some formats go even further and include camera positions and lights so the scene opens the way the author set it up. Others can also hold animation data such as bones, keyframes, or motion paths, which turns the file from a static model into an asset that can move. That explains why opening a 3D file can sometimes recreate not just the object, but also the whole shot.

There are so many different 3D formats because 3D was developed separately for different goals. Older and desktop 3D programs created their own project files to save scenes, materials, and animation. Game engines and some titles created leaner formats to make assets load faster. Engineering and architecture tools preferred precise formats designed for measurement and manufacturing. Later, web and mobile needed lightweight 3D so products could be viewed online or dropped into AR. Over time this produced a long list of 3D-related file extensions, many of them fairly obscure. These files still show up in old project folders, client deliveries, training materials, and game assets, even if the original program is no longer installed.

In real workflows, 3D image files often sit in the middle of something important. A studio may have created a character or prop in a small or older 3D tool and saved it years ago. A learning team ma extension was used by a game to bundle several kinds of data, so it is not obvious from the name alone that 3D data is inside. Sometimes there is no thumbnail at all, so the file looks broken even when it is fine. Being able to open or at least identify the file helps rule out corruption and tells the user whether they simply need to restore the original folder structure.

It is also common for 3D files to be only one piece of a set. A model can reference external textures, a scene can reference other models, and animation data can be meant to work with a base character file. When only one of those parts is downloaded or emailed, the recipient sees just one mysterious file. If that file can be identified first, it becomes much easier to request the missing parts or to convert it to a simpler, more portable 3D format for long-term storage. For teams that collect assets from multiple sources, or users who work with old projects, the safest approach is to identify first and convert second. If the file opens today, it is smart to export it to a more common 3D format, because niche formats tend to get harder to open over time.

In summary, this type of 3D resource is best understood as a structured container for 3D information—shape, appearance, and sometimes animation—created by many different tools over many years. Because of that diversity, users frequently encounter 3D files that their system cannot open directly. A multi-format tool such as FileMagic makes it possible to see what the file really is, confirm that it is valid, and choose the right specialized program to continue the work, instead of guessing or abandoning the asset.