BI motion sensor zone grid size

[lovemyram4x4]

I'm just curious about something I just noticed. If I turn on the HD setting on the motion sensor configuration menu the zone grid size changes like if you change 4MP resolution to a 2MP resolution. This doesn't really make any sense to me, if it does 4x the samples I'd think if anything it would make the grids smaller not bigger. Maybe it has to do with minimizing CPU loads.

Not that it's really important to me at this time since I don't have problems picking up motion with HD setting off but if some how I could tune things for less false triggers with it on I'd use it, however the larger grid blocks are harder to run up a tree I'd like to only trigger if something passes on the camera side.

Anyone have any idea why the this setting changes does this?

 

[lovemyram4x4]

Well I figured out what was casing the backwards grid sizes. The camera's default resolution is 2688 x 1520 which isn't a true 16:9. I used the force size setting to 2688 x 1512 and now when HD is unchecked I get larger grid size on zones and smaller ones when HD is checked as one would expect.

Ironically I only discovered this because I had noticed a line on the side of the picture on one of my tablets and had used this setting for another camera for a different display issue. Forcing the new resolution fixed the line issue but also made my have to redo my zones.