Ibt File Extension
Ibt extension stands for Texture and model files. You may open ibt files with T3ed Level editor.
It is model and texture file that used with some computer games. For example: These files are used with "Eidos Thief: Deadly Shadows" game.
When you develop a model with 3dsmax software, you may use your model in the games with the assistance of T3ed software. You can get it free via internet.
What needed to Open Ibt file extensions.
T3ed Level editor
Links about Ibt file extension