dPVS is an acronym for Dynamic Potentially Visible Sets.
dPVS by Umbra Software is an advanced computer graphics visibility optimization tool. Designed for developing games with large and dynamic [3D] worlds, dPVS computes visibility databases in real time. dPVS also reduces the time required for static PVS computation.
Your art team and world builders are responsible for visibility. This is done using two mechanisms:
The dPVS technology is built into the HeroEngine client and helps control which items are visible. Determing that something is not visible (because it is behind something else, etc.) allows the 3D engine to avoid drawing such objects. This is key to maintaining high frame rate!
To disable dPVS, there is a checkbox in the Renderer panel. Turning off dPVS will cause the system to switch to something called Frustum culling which means it will not render anything that is outside the viewing angle of the camera. However, it may still render other normally culled objects (such as a tree behind a building). This may slow down performance, but might be needed for debugging purposes.
For more information on Frustum culling, see the Wikipedia page.
See also: dPVS on Wikipedia