Environment maps are raster themes that display fuel moistures and weather conditions across the landscape at a specific time. They can be useful in understanding how the topography, forest canopy structure, and weather affect the fuel moisture and local environment during a simulation.
Environment maps can be generated any time after the fuel moistures have been calculated. By default, your simulation will precalculate all fuel moistures before the simulation starts. If you selected to calculate the fuel moistures at the time they are needed, then you will only be able to create environment maps up until the last time of your calculations. The Output > Environment Maps command brings up the "Fire Environment Maps" dialog box.
The dialog box gives the time range available for requesting environment maps. Maps are available at each time step of the simulation. To request a map for the current time step simply check the Now checkbox. To specify a environment map from a previous time step clearing the Now checkbox allows a date and time to be entered.
Select a radio button for the desired Output Map and an Output Resolution. Be cautious when selecting Native LCP Resolution as this creates large files sizes, generate a test file and check it's file size before generating very many maps.
Click the Output File Name button to give the output map a name. Give a descriptive file name as all the output maps have the same .ASC extension.
Click OK in the "Fire Environment Maps" dialog box to generate the raster output file.
Generating the environment map file puts the following legend with the file name in the "FARSITE Simulation Legend" window;
You should enlarge the "FARSITE Simulation Legend" window if there are more than a couple of vector or raster map legends showing.
Display the Environment Map by checking the 2D or 3D checkbox, corresponding to the 2D or 3D landscape view.
Raster files are displayed in the default black to red gradient. Environment map colors can be changed in two ways;
by changing to one of FARSITE's pre-built color schemes,
changing individual legend colors.
Often it's helpful to reduce the number of colors for a raster map as it becomes hard to differentiate between the colors when there are more than eight to ten.