On v3 machine, we used to link to another software to do visualising.. where we can set the screen size.. and the distance, height and angle of projector in ft or m. It helps us to overview the entire project.
but can we do the same in V4 built in visualiser.. i saw position of screen in numbers. but not sure what units.
Units is Hippotizers Visualizer relate to whatever Units your model was made in. If you made your model originally in Meters then 1 unit is 1 meter. If your model is made in Centimeters then 1 unit is 1 CM. Millis, Inches, Feet, will all work the same.
If you are doing projector analysis in SHAPE then you can set your unit display in Edit, Preferences, Scene. It is then clear what units you are working in.