Files with tddd file extension can be found 3D graphics files for astronomy software from Imagine.
Software that open tddd file
TDDD file extension - Imagine object file format
What is tddd file? How to open tddd files?
File type specification:
The tddd file extension is used for Imagine object file format. It is a three-dimensional image data used by astronomy applications. It stores data relating to the object and observer. These files are used in Inpulse Turbo Silver or Imagine applications.
The default software associated to open tddd file:
Imagine Stage/Object Examiner (ISOE) 
Company or developer:
Imagine
Imagine Stage/Object Examiner (ISOE) utility allows examination of Stage (.ISTG or .IST) and Object (.TDDD) files.
List of software applications associated to the .tddd file extension
Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open tddd file, edit tddd file, convert tddd file, view tddd file, play tddd file etc. (if exist software for corresponding action in File-Extensions.org's database).
Hint:
Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is able to perform the specified software action, such as opening, editing or converting tddd files.
tddd file viewer - programs that view tddd file - Imagine object file format
Programs supporting the exension tddd on the main platforms Windows, Mac, Linux or mobile. Click on the link to get more information about Imagine Stage/Object Examiner (ISOE) for view tddd file action.
