...Along came a spider, who sat down beside her, and frightened Miss Muffett awake!
Our new Lennar home (designed in AutoCAD) is a smart home. Lots of devices like lights, locks, and home entertainment are controllable by smartphone apps as well as the Amazon Alexa service. Two of the devices that we have are Ring doorbells — one for the main entrance and a second for the entrance to the in-law unit. Ring doorbells include a camera so that homeowners can see who is at the door before bothering to answer the ring of the doorbell. Ring doorbells also include a microphone and speaker so that the homeowner can communicate with the person at the door before opening the door. This is particularly handy when answering the door when not at home. The owner can communicate with the person at the door using a smartphone app regardless of where the owner is physically present.
Towards this end, Ring doorbells provide smartphone ring alerts when a doorbell is rung. As a security feature, Ring doorbells also provide motion alerts even when the doorbell is not rung. This feature alerts the homeowner to the presence of someone at the door who may be up to no good, such as stealing a package. In addition to the alert that is sent to the smartphone, the camera in the Ring doorbell records the motion in case the video needs to be supplied to the police.
The Ring doorbell motion sensor is simply a pixel comparison algorithm. The camera constantly takes a frame of video. It then takes the next frame. It compares the two frames. If they are different, it interprets this as motion. In other words, something has changed. The Ring doorbell allows the homeowner to set the sensitivity of the comparison process.
On the most sensitive setting (ALL MOTION), even something as small as a falling leaf will cause an alert. Only a few pixels in the successive frames need to differ to trigger a smartphone notification. On the least sensitive setting (PEOPLE), a lot of pixels need to change to trigger an alert.
In addition to the setting the sensitivity, the homeowner can set the motion zone. This tells the algorithm what pixels to compare.
I have my motion zone (highlighted in light blue) set so that the window next to the door (on the far left) is excluded. Before doing this, we got alerts every time we turned the lights on or off. Our zone also excludes the street (on the far right). Before doing this, we got an alert every time a vehicle passed our house.
With my motion sensitivity and motion zone all set, imagine my surprise when I got an alert at 2:30 am early Wednesday morning. It woke me up. I really worried that someone was lurking at my front entrance. I checked the video:
Although I have the sensitivity more towards PEOPLE ONLY, the insect (a crane fly) was so close enough to the physical camera that her body occupied a lot of pixels.
An adult crane fly, resembling an oversized mosquito, typically has a slender body and stilt-like legs that are deciduous, easily coming off the body. The wingspan is generally about 1.0 to 6.5 cm, though some species can reach 11 cm. The antennae have up to 19 segments. It is also characterized by a V-shaped suture on the back of the thorax and by its wing venation. The rostrum [beaklike snout] is long; in some species it is as long as the head and thorax together. [wikipedia]
Hopefully, she (I’ll call her Denise) was just passing by and will find a home at someone else's house. I was surprised to be awoken in such a manner. “You were at my wedding, Denise.” 
Motion capture is alive in the lab.