Here you enter the non-spatial inputs and control how the fire behavior characteristics are calculated.
An ignition shapefile is a required Farsite input. Ignitions can be shapefiles created elsewhere or within FlamMap by selecting one of the Option > Pointer Mode > Create... options.
Click the 
button to display three Ignition File options,
A barrier shapefile is an optional Farsite input.
Shapefiles can be used in FlamMap runs to simulate barriers to fire spread that may not be represented in the landscape. For instance, if you know that a creek or road is a barrier to surface fire spread, but landscape data show that some or all of the cells are burnable in the area represented by the creek, you could create a barrier file. Keep in mind that fire barriers will block surface fire spread. However, torching trees could cause the fire to spot over the barrier (in reality as well as within the fire behavior model).
Barriers can be shapefiles created elsewhere or within FlamMap by selecting one of the Option > Pointer Mode > Create... options.
Click the 
button to display the Barrier File options,
Selecting the Fill Barriers check box will fill a polygon barrier with unburnable cells so spots cannot start new fires inside the polygon. This option has no effect on a line barrier.
These model settings significantly affect the run time and precision of your simulation, unfortunately these two characteristics are inversely related.
The Perimeter Resolution setting controls the spacing of points along the simulated fire perimeter where fire behavior characteristics are calculated. Increasing this distance will speed up processing time. This distance should not be set below the landscape resolution as any points within the same landscape cell will have the same fire behavior. The Perimeter Resolution is closely related to the Distance Resolution and Time Step settings so all three should be considered when modifying any one of them. See Huygens' Principle Technical Documentation topic for more information.
The Distance Resolution setting controls the spacing of calculation points between time steps in the direction of fire spread. Increasing this distance will speed up processing time. This distance should not be set below the landscape resolution as any points within the same landscape cell will have the same fire behavior. The Distance Resolution is closely related to the Perimeter Resolution and Time Step settings so all three should be considered when modifying any one of them. See Huygens' Principle Technical Documentation topic for more information.
The time step is the maximum amount of time that the conditions at a given point are assumed constant so that the position of the fire front can be projected. The Time Step setting also controls the interval for the Farsite Perimeters outputs. A shorter time-step becomes more appropriate with faster fire spread rates.
The time step is really of secondary importance compared with the spatial resolution of the calculations (as determined by the perimeter and distance resolutions above). The internal time step used by the simulation is constantly changing according to the minimum time required for the fire to spread the distance equaling the distance resolution. The actual time step is thus, only used as a consistent period during which all fires will be projecting to a coincident time before mergers and spotting are computed. See Huygens' Principle Technical Documentation topic for more information.
Fire acceleration can be used in FARSITE to "smooth" the transition to different spread rates caused by changes in fuel, topography. and weather. With Use Acceleration unchecked the rate of spread will change instantaneously when conditions change. See the Fire Acceleration Technical Topic for more information.
An Ember Spot Probability of zero will prevent any spot fires from occurring, effectively disabling the spotting feature. See the Spotting Technical Topic for more information.
Spots typically do not begin spreading the moment a live ember lands on receptive fuel. They tend to take time to ignite the surface fuels and smolder a bit before flaming and spreading, the Spot Delay setting is an attempt to simulate this typical behavior. A Spot Delay greater than zero will reduce the effect spotting has on the overall perimeter growth.
Most lofted embers will land close to the current perimeter. May of these spot fires will be quickly overtaken by the main fire, especially if a spot delay and/or acceleration are used.
Setting the Minimum Spot Distance greater than zero will prevent live embers from igniting spot fires within that distance of the current perimeter. This will speed up the simulation as Farsite does not then spend computational effort tracking and merging these insignificant spot fires. See the Spotting Technical Topic for more information.
Even spot fires beyond the minimum spotting distance can be clustered in a small area. The Background Spotting Grid Resolution setting is used to minimize the number of spot fires near each other by creating a grid of the specified resolution and only allowing one live ember to ignite a spot fire in each cell. This will speed up the simulation as Farsite does not then spend computational effort tracking and merging these insignificant spot fires. See the Spotting Technical Topic for more information.
Foliar Moisture Content is the moisture content of the crown fuels. This is not related to the live fuel moisture of the surface fuels.
Select either Finney (2004) or Scott/Reinhardt (2001) from the drop-down menu for Crown Fire Calculation Method.
See the Crown Fire Technical Topic for more information.
ROS Adjustment (.ADJ) Files are optional.
Click the 
button to display several ROS Adjustment (.ADJ) File options,
The "Farsite Run:" dialog box/tabs have a status bar and functional buttons at the bottom to help you keep track of where you are at with the set up process.