MASK_TILE is a mapper module that produces a geometry from an input
field and color map.  If any data point falls below the color scale, 
this sets its color to the mask color.  For optimization of Z slices, 
adjacent squares on the same row of identical color will be drawn as 
a single polygon of that color.
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The MCNC Environmental Programs Group has created this module as part of a
suite of AVS demo modules, networks, and sample data sets to demonstrate 
the functionality of its visualization prototype for an Environmental 
Decision Support System (EDSS).  This system provides a unified method of 
analysis and visualization for data output from different environmental air 
quality models.  Remotely, standard output files from the following models 
can be read into AVS:

        ROM (Regional Oxidant Model)
        RADM (Regional Acid Deposition Model), low res and high res
        RADM (Regional Acid Depostion Model) Emissions, low res
        UAM (Urban Airshed Model, regulatory version)
        UAM (Urban Airshed Model, AREAL research version)
        UAM Wind (Urban Airshed Model, regulatory version)
        MCNC ALPHA-Prototype netCDF files

Alternatively, xdr portable binary AVS fields can be created from these
data types and accessed directly from the local workstation.

You can download these modules individually from the IAC using anonymous
ftp to the appropriate directories /avs_modules at avs.ncsc.org.  
If you would like to download the entire suite of modules, networks, and
sample datasets at the same time, the IAC recommends that you use 
anonymous ftp to grab the following file from avs.ncsc.org -

/sample_data/avs_data/MCNC_Env_Pgms/MCNC_Env_Pgms.tar.Z

This contains all source code to all local and remote modules, as well as
all of the sample datasets, networks, documentation, installation, and
usage notes.
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