The MTT Perimeters output contains the final perimeters of the modeled fires generated by random ignitions or from a Fire List File. For MTT runs using an ignition file see the Arrival Time topic.
NOTE: For viewing clarity this image displays only a few perimeters, typically a burn probability run will have hundreds or thousands of overlapping perimeters.
The number listed in the Fire Number (Fire_Num) field is the same Fire Number listed in the Fire Size List File. Fire Numbering starts with 0 and ends with the number of specified ignitions minus 1. For example, if 100 random ignitions are specified the range of fire numbers will be 0-99. This file can ONLY be saved in a shapefile format from FlamMap. It can be used in a GIS or loaded into FlamMap as an Auxiliary Vector Theme.
Farsite Perimeters output will display multiple perimeters from a single ignition file.
In addition to the final perimeter Farsite includes the perimeters at end of each timestep, as set in the Model Settings tab. In the above example the Arrival Time grid provides a good depiction of the daily spread due to the relatively short burning periods (5-6 hours) and the color ramp choice.
The visible perimeters can be modified with the "Farsite Perimeters" dialog.
The perimeters can also be saved in the shapefile format and used in a GIS or loaded into FlamMap as an Auxiliary Vector Theme. The shapefile attribute table also contains other data about the perimeters, such as area and times.
Perimeter attribute table as viewed in a GIS.
Perimeter times reflect the end of the timestep, so a one hour perimeter labeled 1300 reflects the fire growth from 1200 to 1259.