Athens County
Cooperative Land Administration
and Information Mapping system
March 31, 2003
Athens County Commissioners
15 South Court Street, 2nd Floor
Athens, Ohio 45701
RE: Monthly GIS Progress Report
Commissioners:
Our Orthophoto/Elevation Contours project is complete.
All data has been received and the bill is paid. We had a great
experience with Sanborn Colorado and have excellent new photos
and topo data four times better than our previous data.
ILGARD has received a new data set from the Auditor's Office.
This will update all transfers that have occurred since the last
data set a few weeks ago. Property splits are current within a
one-week period. This one-week period will decrease to one day
once the Auditor upgrades to version 4.0 of the CLT Operating
System. Two students are working on rectifying missing Parcel
Identification Numbers for Athens Township. The Auditor's Office
automated plat map printing system is now operational.
The system is similar to the one on our website.
The Auditor has identified a type of printer that meets their GIS
needs. They are obtaining quotes from different sources.
The CLT upgrade to 4.0 may happen quicker that we originally
anticipated.
The recent ILGARD training session for ArcView was very
successful. Mark Hall from the City of Nelsonville attended the
classes and reports that he has started using ESRI ArcView
software and is excited about the possibilities he sees for GIS
in Nelsonville. Mark reported that they have used GPS to locate
all their manhole covers. JB agreed to plot this data as a GIS
layer and Mark plans to start assigning available attribute data
to their database.
I will meet next month with Jill Harris, Athens County Emergency
Management Agency, to begin to study a strategy for GIS to be
used in Homeland Security work.
I will attend a class on Managing GIS Implementation to be held
as part of the 2003 URISA Integrating GIS and CAMA Conference in
Columbus March 30 - April 2.
Our next GIS Steering Committee meeting will be May 15th
at 10:00 A.M., in the ILGARD conference room.
Attached is an article from ESRI regarding a future ArcGIS
software update. ArcGIS 9 will provide a unified framework for
geo-processing that includes new tools and new methods for
working with all tools.
Thank you for allowing me to coordinate this important aspect of
Athens County's future.
Archie Stanley - GIS Coordinator
555 East State Street - Athens, Ohio 45701
Phone (740) 593-5514 - Fax (740) 592-4616
E-mail: astanley@frognet.net
_______________________________
Geoprocessing--The Road Ahead
Geoprocessing is an integral part of a GIS and is based on a
framework of data transformation. A typical geoprocessing
operation takes an input data set, performs an operation on that
input data set, and returns the result of the operation as an
output data set.
A model contains processes. Each process has one or more input
data sets, a function, and output.
The term geoprocessing has come to mean many things to many
people. Although some people would say that geoprocessing
strictly consists of spatial analysis functions, ESRI defines
geoprocessing as the creation or modification of data, which is
typica lly spatial in nature, by a function that has one or more
parameters. In this manner, geoprocessing functions include
analysis functions (overlay, buffer, slope), data management
functions (add field, copy, rename), and data conversion
functions.
Unified Framework With New Tools
The new ArcGIS geoprocessing environment will have hundreds of
geoprocessing tools for processing all types of data. Tools are
organized in toolboxes, which exist in folders and geodatabases.
The ArcToolbox window organizes toolboxes into a list of
favorites for easy access from within the ArcMap and ArcCatalog
applications. ArcGIS extensions add more geoprocessing tools that
work like any other tool so all geoprocessing functions in ArcGIS
behave and look the same, with only their parameters an d
execution being unique. Below are samples of tools that will be
available in ArcGIS:
- Overlay Tools--Union, Intersect, Erase
- Proximity Tools--Buffer, Near, Point Distance
- Data Management Tools--Create Feature Class, Add Domain,
Delete Field
- Surface Analysis--Aspect, Hillshade, Slope
Approximately 400 tools will be released with ArcGIS 9 including
tools for extensions such as ArcGIS Spatial Analyst. More than
100 new tools will be provided that work with any type of
feature class such as a geodatabase feature class, shapefile, or
coverage feature class. The number of functions will vary
depending on the software used. More geoprocessing tools will be
available in ArcEditor and ArcInfo than in ArcView.
The next major release of ArcGIS will include new geoprocessing
tools and four methods to access those tools (above: dialogs,
below are examples of ModelBuilder, command line, and scripting).
Geoprocessing Methods
Experience shows that no single user experience satisfies all
user requirements and preferences for geoprocessing. The best
method depends on the particular task and personal preference.
Within ArcGIS, users will have a choice of four different metho
ds for performing geoprocessing--ModelBuilder, dialogs, command
line, or scripts. To perform complex geoprocessing tasks
involving multiple functions, create a new model tool and link
processes together in a visual diagram using ModelBuilder. For
sin gle geoprocessing tasks, use tool dialogs found in toolboxes
or use the command line. To perform the same function many times
on different data sets, use or create a tool derived from a
script. A brief discussion of the different geoprocessing
methods follows.
ModelBuilder
ModelBuilder is a window for visually constructing geoprocessing
tasks and spatial models. A model contains information about
spatial data, how to process the data, and the sequence of
processing. The diagram below is a conceptual overview of a model
built from three processes. Each process has one or more input
data sets, a function, and output data. Connecting the output
from one process to the input of another process chains the
processes together.
Geoprocessing functions can be tied together in a model that
keeps track of the data sets, processes, parameters, and
assumptions. Models can be saved, modified, and rerun. The model
can be displayed as a process flow called a model diagram or as a
tool in a toolbox. A tool exposes model parameters selected by
the model author and is the common way of executing a model.
Model tools have the following benefits:
- Are easy to understand, self-documenting, and sharable
- Provide GUIs such as dialogs, wizards, and property sheets
- Work with all tools including tools unique to extensions
- Save long processing sequences and rerun them easily
- Create complex models without writing scripts
- Store metadata about the model with the model
ModelBuilder is integrated into ArcGIS Desktop and is not a
stand-alone application. The model diagram and the results from
ModelBuilder can be placed into a layout in the ArcMap
environment.
Dialogs
Toolboxes contain dialogs that guide users through the process of
running a geoprocessing task. Dialogs provide a form to specify
the data and parameters for a geoprocessing operation. Dialogs
are practical when users want to execute a single operati on
using an easy-to-use interface or do not want to type the syntax
in a command line. All of the tool dialogs have a help panel that
can be opened to display help topics.
Command Line
Regardless of the ArcGIS Desktop software installed (ArcInfo,
ArcEditor, or ArcView), users can access a command line similar
to the ArcInfo Work station command line. Typing the function
name, the input data set(s), and the required parameters produces
the same result that would be achieved in a dialog. Command line
can be quicker to use than a dialog if the command and its
associated parameters are known.
The command line window prompts users with the usage of the
specified command, so the user would always know what parameter
is being defined. It is also aware of which available inputs are
valid for a parameter and presents those values in a drop-dow n
list from which the desired value can be selected. These lists
include layers in the map you are using, keywords for the current
parameter, or user-defined variables.
Scripts
Geoprocessing tasks can be time intensive since they are often
performed on a number of different data sets or large data sets
with numerous reco rds. Scripting is an efficient method for
automating geoprocessing tasks. Scripting allows the execution of
simple processes (single function) or complex processes
(piggybacked, multifunction tasks with validation). In addition,
scripts are recyclable, meaning they can be data nonspecific and
used over again.
The geoprocessor is a common object model (COM) object that
manages all of the geoprocessing functions available within
ArcGIS. This object provides a single access point and
environment for the execution of these functions. The
IGpDispatch interface implements automation and makes it
possible for interpretative and macro languages to access COM
components. This interface allows modern scripting languages to
execute ArcGIS geoprocessing functions.
Which scripting language to choose is an open question. Any
scripting language that is COM compliant, interacts well in a
Web-based environment, and allows users to complete their tasks
is a viable option. While there are a number of good scripting
languages on the market, for simplicity this article will mention
three of the more popular languages that meet the necessary
criteria: VBScript, JScript, and Python. VBScript and JScript
are familiar to many people and are relatively simple languages
similar to Visual Basic and C that are designed to operate in a
Windows environment. Python is a moderately easy-to-learn
language similar to C. Python and has the ease of use of a
scripting language along with the programming capabilities of a
complete developer language. Moreover, Python is platform
independent and can operate on a variety of operating systems
including UNIX, Linux, Macintosh, and Windows. For more
information, visit www.python.org
ArcGIS scripting is similar to using ARC Macro Language (AML) or
Avenue, although the user is not constrained by a proprietary
language.