Did some simple testing to determine the camera angle, resolution and suitable dual laser dot separation. Kitty was sat on a stool, looking up at the ceiling, and I was waving the laser around the ceiling watching the curses display. The picture below is upside down!
U______________ ∧ ^ ^ /|\ 21cm | / | \____V | / | \ 205cm / α | \ | / | \ | / | \ | /______|______\______V |<----170cm---->|
U = camera position
Span of kitty laser dot detection = 170 x 170cm
Test height (camera to ceiling) = 205cm
Alpha = atan(170 / (2 x 205) = 22.5°
Camera height at takeoff = 21cm
∴Camera span at takeoff = 17.4 x 17.4cm
Image size = 32 x 32 pixel
∴Image resolution at takeoff = 0.5 x 0.5cm
Landing leg separation = 23cm
Based on the above, 2 dots spaced by 15cm would make a good laser leash
Image span at 1m hover = 82 x 82cm
Double dot separation viewed from 1m = 15cm / 82cm x 32 pixels ≅ 6 pixels
So minimum capture resolution of 32 x 32 pixels should be fine for 1m hover, but by 2m, the risk of merged dots is too high as they’ll only be 3 dots apart.