= Multi Agent System (MAS) =

The embedded Multi Agent System (MAS) allows for the modeling of pedestrian movement in complex (urban) terrain. The following text provides an overview of the model's functionality as well as underlying concepts. This will cover the topics of creating a visibility graph, pathfinding, and Social Forces for collision avoidance.  \\\\
For a list of input parameters, see [wiki:/doc/app/agtpar agents_par]. 

== Navigation ==

This section contains information concerning agent navigation. This includes preprocessing (creation of a visibility graph) and online steps (during simulation).

=== Visibility graph ===
Prior to a simulation using the MAS navigation information for the agents must be preprocessed. The result is a navigation graph that agents can use to find their way around obstacles toward their target.

'''Concept'''\\\\


'''Creating the visibility graph'''\\\\
A tool separate from PALM has been developed to calculate the visibility graph. It is a standalone Fortran program (find it at {{{UTIL/nav_mesh/nav_mesh.f90}}}). \\
'''The usage of this tool is subject to chage! The following description is preliminary!'''

1) Copy {{{nav_mesh.f90}}} to the {{{INPUT}}}-folder of your JOB.\\
2) Compile it, including your NetCDF-libraries. At IMUK the command is (replace the paths according to your local NetCDF installation):
{{{
ifort -cpp -I /muksoft/packages/netcdf4_hdf5parallel/4411c_443f/hdf5-1.10.0-patch1/mvapich2-2.3rc1/intel/2018.1.163/include/ \\
           -L /muksoft/packages/netcdf4_hdf5parallel/4411c_443f/hdf5-1.10.0-patch1/mvapich2-2.3rc1/intel/2018.1.163/lib -D__netcdf -lnetcdf -lnetcdff nav_mesh.f90
}}}
3) Make sure your Input folder contains the relevant topography information in either an ASCII- or NetCDF-file ([wiki:doc/app/iofiles/pids#topo see here]).\\
4) Make sure your Input folder contains the {{{_p3d}}}-file. In it, if necessary, specify the namelist {{{&prepro_par}}} with the parameters [#flag_2d flag_2d], [#internal_buildings internal_buildings] and [#tolerance_dp tolerance_dp].\\
5) Execute the program
{{{
./a.out
}}}
This will create a file {{{<job_identifier>_nav}}}. This is a Fortran binary file that contains the polygon and visibility graph data and will be read by PALM during the simulation. As long as the area and resulution of the model domain do not change this file can be reused. 

''L'', ''u'',,∗,, as well as
{{{
#!Latex
$\overline{u_i^{\prime\prime} u_3^{\prime\prime}}$
}}} 


== NAMELIST group name: {{{agents_par}}}==

||='''Parameter Name'''  =||='''[../fortrantypes FORTRAN Type]'''  =||='''Default Value'''  =||='''Explanation'''  =||
|----------------
{{{#!td style="vertical-align:top; text-align:left;width: 150px"
[=#tolerance_dp '''tolerance_dp'']
}}}
{{{#!td style="vertical-align:top; text-align:left;style="width: 50px"
R * 5
}}}
{{{#!td style="vertical-align:top; text-align:left;style="width: 75px"
100 * .F.
}}}
{{{#!td
Array for simplification of building polygons during preprocessing.\\\\

}}}
== References ==
* [=#detering1985] '''Detering HW, Etling D.''' 1985. Application of the ''E''-''ε'' turbulence model to the atmospheric boundary layer. Bound.-Lay. Meteorol. 33: 113–133.