3D imaging for content monitoring using Stereo Camera (Arducam or similar) and Raspberry Pi

I need to develop a hardware that will use a stereo camera and raspberry to monitor the content of a rectangular box and keep monitoring its contents... when the box is becoming empty. I need to get and alarm to replenish the content. The project would be separated in 2 phase where Phase 1 is proof of concept and Phase 2 is own hardware development with extra features. Competency needed for phase 1: Experienced Raspberry programmer with knowledge with 3D imaging using Stereo cameras and zone creation with logics to active alarms. The image treatment should take place in the raspberry itself and not in an external computer. If the prototype works fine, later will be needed to add a SIM Card for cloud communication, power management system to avoid power fluctuations and a temperature sensor. The prototype should identify the aprox ocupancy of the box zone wise (maybe 4/5 zones) and send an alarm when level is lower than a pre-established parameter.