1. A method for producing an image of a gas of interest in excess of a background concentration, where the gas is within a scene having a surface, the method comprising: providing a backscatter absorption gas measurement system for generating a plurality of light beams to illuminate the surface and for receiving a plurality of light beams reflected back from the surface, wherein the generated light beams comprise a first plurality of beams comprising first and second wavelengths of light and an alternating second plurality of beams having first and third wavelengths of light, and wherein the first wavelength of light is absorbed by the gas of interest; determining an indication of absorption of the gas of interest at each portion of the surface within the scene using a differential absorption measurement determined from the first, second and third wavelengths; determining a distance from the backscatter absorption gas measurement system to each portion of the surface illuminated by the backscatter absorption gas measurement system, wherein the distance is determined from the round-trip time-of-flight of the third wavelength of light; and providing an estimate of the amount of the gas of interest in excess of a background concentration from the determined absorption and the determined distance measurement of each portion of the surface, wherein the estimate of the amount of the gas of interest in each portion of the illuminated surface is provided by a processor and presented as a visual display of an image of the scene.