Mounting height and angle affect real-world usefulness more than almost anything except image quality. Work back from the target.

• Indoor corridors: 2.5 to 3 metres with the lens tilted 10 to 20 degrees down balances face capture against corridor coverage.
• Outdoor walls and perimeters: 3 to 5 metres clears tampering and obstructions, but avoid too steep a downward tilt or you will only record the tops of heads.
• Entrances and face recognition points: 2 to 2.5 metres with the lens axis 10 to 15 degrees to the ground. A steeper tilt distorts faces and degrades recognition accuracy.
• Lanes and checkpoints: for a working range of 15 to 30 metres, mount at 2 to 3 metres with a horizontal offset under 30 degrees so plates are not compressed out of proportion.
• Avoid backlight and obstruction: do not aim into strong light or a window, and keep branches, canopies and similar reflective or obstructive objects out of the optical path.

A commissioning tip: mark the target position and the camera position on the plan and derive coverage from the field of view angle. It saves discovering on completion that the view is wrong.