HFire (Highly Optimized Tolerance Fire Spread
Model) is a new raster-based spatially explicit model of surface fire spread through Southern
California chaparral written in the C programming language. Using HFire you can predict the
speed and direction of a fire spreading across the landscape in real-time. HFire can also be
used for stochastic multi-year simulations of fire regime.
The HFire model is a product of research funded by NASA through the
Southern California Wildfire Hazard Center.
HFire is also the basis of my masters thesis at the University of California, Santa Barbara.
I have released all of the source code under the
GNU Lesser General Public License.
The native output of the simulation is ASCII raster files showing predicted fire spread. ASCII
raster files can be read by any general purpose geographic information system (GIS) or remote
sensing software. The simulator also supports the output of PNG images if you have the fantastic
open source gd library installed on your machine. See the
makefile included with the distribution for more details on enabling this option. The
html documentation generated from the HFire library source code is a
good place to go if you are interested in extending the capabilities of HFire or developing your
own simulator. HFire is written in C. In order to support model intialization from a wide
variety of input data source formats without the benefit of an object-oriented system, I used
tables of function pointers to achieve polymorphism. A good example is the
FireEnv struct. The documentation for the HFire
configuration file is a good place to scope the features
available from the library.
HFire uses the Rothermel fire spread equation
(Rothermel, 1972) to
determine the direction and magnitude of the maximum rate of fire spread into a cell.
One-dimensional predictions from the Rothermel equation are fit to two-dimensions using
the solution to the fire containment problem
(Albini and Chase, 1980)
and the empirical double ellipse formulation of
Anderson (1983). A new technique
implemented in HFire, based upon finite fractional distances between cell centers,
remedies the problem of distorted fire shapes previously identified as endemic to
raster models of fire spread
(French, et al, 1990).