Control over the angle in 3D space that your model should load to give customers an experience that makes it undisputably obvious what section on the model they are customising.
The units are in degrees and can be anything from 0° to 360°.
Latitude spins on the horizontal access. Longitude spins on the vertical axis.
Radius is the zoom of the model. What this should be set too is entirely dependant on how your model is set up. A safe place to start is at 0° and then you can go minus (-0.5° for example) if your model is too zoomed in or go up to (3° for example) 10 to zoom out your model further.
Note: it is also advisable for 3D models to be made roughly life size or smaller. It is also advisable to set up all your models in the same rough sizes in 3D space so that the radius is a consistent number between models.