Combines optical gas imaging (OGI) camera technology with cross-section pixel absorption algorithms to numerically estimate emissions rates. The brightness of each pixel seen through the OGI camera is proportional to the amount of infrared radiation incident on the camera along the corresponding line of sight through the plume. The brightness is converted to a concentration and combined with estimated velocities to obtain mass fluxes. Accuracy of quantification can be affected by wind, temperature, humidity, visibility, and daylight. Source