I’ve discussed and given examples in recent
newsletter articles of how shapefiles are displayed on the PEAC Mapping Tool
that is integrated into the PEAC-WMD application. This month I’ll discuss a few more details that may be useful for
those users that have access to other mapping or GIS (Geographic
Information Systems) tools that can import shapefiles.
With the release of PEAC-WMD software (version
5.5), AristaTek added a useful resource integrated into several computational tools
in the application - the ability to display a calculated exclusion zone or
standoff distance on a street map. The
result was a graphical representation of a hazard zone, represented by the
appropriate polygon (circle or multi-sided figured) laid over a street
The PEAC Mapping Tool was designed to provide
very basic features and was not intended to be a user’s primary mapping or GIS
application. Rather the tool was to
provide the user with a quick representation of the calculated hazard zone displayed
to scale on a street map without the user having to exchange or transport
information between multiple applications.
Nevertheless AristaTek has had numerous requests on how can the hazard
polygon be captured or the information ported to another application?
I’m not an expert on shapefiles but I can provide some very
basic information on what they contain and how they are organized or stored
within the PEAC-WMD application.
The shapefiles and their
format were developed and established by Environmental Systems Research
Institute, Inc. (ESRI), 380 New York Street, Redlands, CA 92373-8100 USA, which is a
major commercial developer of GIS and mapping applications. The information stored in the shapefiles is
not related to topological features but is related to some multi-sided
geometrical figure (polygon) that represents a point, line or area feature to
be displayed on a map. ESRI provides a
white paper written in 1998 that describes the format of the shapefiles and can
be found at: http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf
As described in the white paper, an ESRI shapefile
main file in which each record describes a shape with a list of its
index file where each record contains the offset of the corresponding main
file record from the beginning of the main file
dBASE table that contains feature attributes with one record per feature.
The prefix name for all three files is the
same and the suffix for the main file is “.shp,” the suffix for the index file
is “.shx,” and the suffix for the dBASE table is “.dbf.”
mapping and GIS application allow importation of a shapefile via an import or
other utility provided in the application.
If a reader has a separate mapping or GIS application, then the User’s
Manual or Help topics should provide some guidance to how this feature is
shapefiles are written to the local hard drive, all three files are typically
displayed, e.g., prefix_name.shp
. Most mapping or GIS applications will allow
the user to import the shapefile by providing a browser window that searches
the available network folders and selects the desired file to be imported. Sometimes the browser will only display the
*.shp files in the folder and not display the associated *.shx or *.dbf files,
while others will display all three associated files. Typically the user selects the prefix_name.shp
which shape file is to be imported and the mapping or GIS application will
automatically access the required information from the other two associated
files. Usually there is no need or
requirement to copy or move the files to a new folder location, at least that
has been my experience.
The PEAC-WMD shapefile organization
help the user find the specific shapefile they want to import to the separate
mapping or GIS application the following discussion will explain how the
PEAC-WMD application names and stores the shapefiles it automatically generates
when the computational tools are executed.
shapefiles are all automatically stored in the following folder:
C:\Documents and Settings\USER_NAME\My Documents\PEAC\Results\Shapes
will vary slightly, depending on your USER_NAME.
is a screen capture of the Windows Explorer for this folder on my PC.
Figure 1 – Windows
Explorer screen capture for some shapefiles on the author’s PC
created five (5) different shapefiles that correspond to the current five
computational tools provided in the PEAC-WMD application that generate
shapefiles as part of their calculations.
The reader should notice that for the three files in the box in Figure 1
all have the same prefix name “PAD_Chlorine_20070601_122109”, and there are the
three (3) separate files discussed earlier, the *.shp, *.shx and the *.dbf
individual computation tools and the protocols they use to create the prefix
name are as follows:
Protective Action Distance or PAD Calculator (plume modeling) use the “PAD_” to
start all prefix names. Then the first
19 alphanumeric characters for the hazardous substance name are added, then the
time stamp as date (yyyymmdd) separated by “_” from the time (hhmmss) to
complete the prefix name.
Fireball Calculator uses the same naming protocol as the PAD but uses “FB_”
rather than the “PAD_” beginning.
3. The Gamma
Dose Calculator uses the same naming protocol as the PAD but uses “GD_” rather
than the “PAD_” beginning.
Explosion Calculator uses the same naming protocol as the PAD but uses “EXP_”
rather than the “PAD_” beginning.
Nuclear Detonation Calculator doesn’t use a hazardous substance name and only
has the time stamp but uses “ND_” rather than the “PAD_” beginning.
in Figure 1, when there are a limited number of shapefiles in the folder, it is
pretty easy to pick out the desired polygon to import into another application
but if there are a large number, then finding the proper shapefile requires the
user to be “on their toes.”
simplest method is to sort the list of associated shapefiles by date if you
know when the computational tool was executed and the shapefile was
created. Then select the specific
shapefile and import it to the separate mapping or GIS application.
have questions regarding accessing the shapefiles, please contact AristaTek
Technical Support at (toll free) 877-912-2200 or 307-721-2126 or via e-mail at