The camera height is just one parameter in all the variables involved in proper camera positioning.
To name a few:
- What is the HFOV of the camera? (This info is published in the Camera Datasheet)
- How wide (horizontally) is the scene that needs to be covered by a single sensor?
- What is the desired detail for the image on the object of interest? (PPF Pixels per foot) (20 PPF is OK for general surveillance, but 80 PPF is high detail, i.e. face recognition, LPR)
- How far is the scene away from the base of the camera? (Distance over ground)
- Are there objects like trees, bushes, cars, buildings etc. that can block the view if placed lower?
In general, mounting the camera high, will allow view over longer distance, wider view, free from occlusion (like trees and bushes)
Mounting a camera low, is more for shorter distance, narrower view, and prone to occlusion (like a truck stopping in front of the camera.
Below is a link for a Field of View Calculator that will help you find the optimal mounting height, based on the FOV information from the Camera Datasheet.
https://www.jvsg.com/calculators/cctv-lens-calculator/