D-Link DNR-4020-16P User Manual page 23

Section 3 - Configuration
Scene
Check this to enable or disable aisle (corridor) mode.
Aisle Mode
Select whether the scene is Indoors or Outdoors.
Scene
From the drop-down, choose whether to display the scene
Mirror
normally or mirror it horizontally, vertically, or both.
The configuration options on this page are only available for
cameras being accessed via private protocol.
D-Link DNR-4020-16P User Manual 18