This system was developed for a Garbage incinerator plant. It monitors the fill level of the main bunker and the hoppers. It is designed to interface into a system that automatically controls the cranes and the fire-fighting equipment.

Bunker fill level monitoring system

Figure 1. Image of the main pit.

The trucks dump the garbage into the main pit (bunker), which measures approximately 40 x 20 x 20 meters. The cranes lift the refuse from the main pit into one of the four hoppers. These cranes are operated automatically using the data fed back from the CCD cameras to the control system. From the hoppers the refuse is fed into the furnaces, where it is burnt. It is important that proper fill levels are maintained in the hoppers to ensure optimal incineration, hence the importance of the automatic operation.
The pit system utilises four CCD cameras to acquire stereo images over the complete pit. The system computes a surface model (DTM) over the garbage from two separate stereo models. The resulting DTM is re-sampled as a DEM (grid cells) and transmitted to the control system. The crane is then automatically activated.
Very significant lens distortion can be seen in the pit image. This is caused by the very wide angle lenses used in this system. However, this distortion is compensated for in the software. The parameters for the distortion are computed during the calibration of the system and are applied during DTM computation.

Hopper measurement system

The hopper system utilises two CCD cameras to acquire stereo images over the hopper area. A DTM and volume of material in the hopper are computed from the 2 images. The resulting volumes are sent to the control system. A single PC can monitor up to four hoppers.
Figure 2. Image of hopper with DTM

Figure 3. Wire frame display of hopper and DTM