When we match viewspeed, what quantity are we actually trying to conserve?

[Tsing]

Hi guys,

I'm trying to intuitively understand viewspeed, and hopefully work towards deriving the formula for myself. However, I'm struggling to understand what quantity we are actually matching when we match viewspeed. For example, if cannot be the angular velocity of the in game view as this would be conserved by 360 distance.

If anyone could point me in the right direction it would be much appreciated! 

[DPI Wizard]

Viewspeed Horizontal is meant to keep the relation between the arc and the chord the same.

Lot's of info here

Viewspeed Vertical is something entirely different, but it's based on the vertical FOV and the end result for 16:9 is almost the same.

[Tsing]

Thanks, I've had more of a read and I think I'm beginning to understand.