1. A method that constructs a two dimensional gas concentration map (image) from one dimensional laser-based projection path data comprising: defining a map having M×N pixels that represents a cross-section plane; identifying boundary coordinate locations on the map that define one or more projection paths where i=1, 2,. .. , I represents the number of projection paths; identifying the map pixels that are traversed by the I projection paths; calculating, via a processor, a pixel projection path length for each map pixel that is traversed by each projection path i; propagating the pixel projection lengths to other map pixels; and correlating the pixel projection lengths.