You might be unable to open a 3D model file (like .obj or .fbx) primarily due to software incompatibility. These are specialized file formats designed to store complex 3D data – geometry, textures, materials, and sometimes animation. While common, they aren't universally readable by all programs. Software requires specific importers or built-in support to correctly interpret the data structure and contents of these files. Using a basic image viewer or word processor won't work because they lack the necessary 3D interpretation capabilities.

For instance, you typically need dedicated 3D modeling, animation, or game engine software. Blender, Maya, 3ds Max, or Cinema 4D can open these files. Game engines like Unity or Unreal Engine also support importing .fbx and .obj files directly. Some viewers like Autodesk Viewer or specialized free tools are also available. If your software should open the file but fails, the file itself might be corrupted, saved in an unusually new version, or rely on missing external resources like texture images.

While widely used, these formats have limitations. .obj is simpler but lacks animation support; .fbx is more complex (handling rigs, animation) but can be proprietary and version-sensitive, causing compatibility issues between different software releases. Always ensure your software is updated. Check for file corruption, required external assets, or try alternative import options within your software. Future formats like USD aim for better standardization, but legacy formats remain prevalent.