1. A method for fire detection, the method comprising: receiving, from a first camera, a first image frame that depicts a first area; receiving, from a second camera, a second image frame that depicts a second area; combining, by one or more processors, the first image frame and the second image frame to generate a composite image frame that depicts a third area comprising the first area and the second area; identify a background frame representing the third area, the background frame generated using past composite image frames of the third area; determining, by the one or more processors, for each pixel of the composite image frame, a difference between a value of a pixel of the composite image frame and a value of a corresponding pixel of the background frame; determining, by the one or more processors, a first set of pixels of the composite image frame, where for each pixel of the first set of pixels the difference between the value of the pixel of the composite image frame and a value of the corresponding pixel of the background frame exceeds a threshold value; determining, by the one or more processors, a smoke frame that corresponds to the composite image frame, wherein a second set of pixels of the smoke frame that correspond to the first set of pixels of the composite image frame are assigned a first pixel value; determining, by the one or more processors, a sum of the first pixel value for the second set of pixels of the smoke frame; determining, by the one or more processors, that the sum exceeds a smoke threshold value; providing, by the one or more processors, an indication that smoke is present in the third area.