If you need to cover a 78 foot wide area with 80ppf, that means you need 6240 pixels across (78 x 80). Since each 1080p camera is 1920 pixels wide, that implies you need just over 3 cameras side by side.
Since 80ppf is fairly high for getting faces / license plates in well, evenly illuminated areas, 3 cameras total might be enough.
The main other consideration is the length of area you want to cover. Since each 1080p camera will be covering a 177 feet long x 26 wide area, this will require a rather telephoto lens (roughly 8 degrees) that will likely have deadspots in areas closer to the camera.
Is the 80 PPF requirement based on facial or license recognition requirements? At what height is the space unobstructed?
As John points out, a simple 3 adjacent camera would have significant blind spots between the cameras. A four camera corner setup would allow a wider lens and less blind spots at the cost of another camera.
A 4 way multi-imager in the center of the room brings the blind spots into the center, add a 360 degree panoramic underneath it, and maybe it would work. But before working the fovs out, one would want to know 1) what's obstructive in the space? 2) can there be any blind spots? 3) do the ceiling mounted cameras have to be flush? 4) and at what angles (from the horizontal plane) are acceptable (tops of heads vs faces )?
Essentially there is four work stations in the area 10 feet high we can't have any blind spots so it's 80 PPF required anywhere in this area ,the cameras can be wall or ceiling mounted with a requirement for facial detection .Thanks for the advise so far .
Seems tricky since, unless the ceiling mounted cameras could be suspended down by a significant amount > 5 ft?, they would have a tough time getting a good enough angle for facial rec. when the subject was close to them. And the more distant views could be obscured by the 10ft high workstations. Are the workstations fixed? I assume no cameras allowed on workstations? Without more specific topological information I'm not smart enough to answer, I fear.
P.S. High-grade mirrored walls are out of the question, right? :)