If you haven't registered, then the program will start in a demo mode. This means that some functions are restricted and you are not able to save or print out your diagrams and calculations. In the demo mode, individual calculations and/or the corresponding diagram can appear distorted by means of a random defocus filter. Please log in with your license key if you want to use DTVD in the scope of an assessment and require reliable results. In order to log in, you have to register once and without commitment.
You can find instructions on how to use the program here: DTVD help
The registration process is described here: Help with the registration
You can buy licenses for immediate activation online here: Order license key
It can take some time for the DTVD libraries to load depending on the Internet connection and the processing power of your computer. After completion of the loading process, close this dialog with the button faded in at the bottom and draw your diagram.