**Problem:**

How do I change the viewing angles Psi, Alpha, and Theta from the viewer’s perspective? Also, please help me understand how these angles are defined.

**Solution:**

Below is a diagram from the 360 User’s Manual describing how Tecplot defines Psi (Ψ), Theta (θ), and Alpha (α).

The following exercise uses PyTecplot to change each of the three angles by 5 degrees and manifests the result after each step.

1) Start with a 1x1x1 cube in the default viewing position in the first quadrant, see Figure 2.

2) Make sure the Tecplot work-space is accepting PyTecplot connections. Go to *Scripting>PyTecplot Connections… *and toggle-on *Accept Connections.*

3) Run the following preliminary commands in a terminal to use PyTecplot (assuming PyTecplot is installed):

C:\Users\user>python>>>import tecplot as tp>>>tp.session.connect()

4) To test changing the Ψ viewing angle by +5 degrees, run the following in the terminal. See the result in Figure 3.

>>> plot.view.psi += 5.0

5) To test changing the θ viewing angle by +5 degrees, run the following script. See the result in Figure 4.

>>> plot.view.theta += 5.0

6) To test changing the α angle by +5 degrees, run the following in the terminal. See the result in Figure 5.

>>> plot.view.alpha += 5.0