hardcopy (three copies) of each quad, and conversion
services of raster files into ARC/INFO vector format.
se St Two - Lake Michigan Ozone Stu MOS
To quantify the ozone source-receptor relationships in the
area surrounding Lake Michigan, a non-profit corporation of
the four states surrounding Lake Michigan jointly funded an
emissions study for the Lake Michigan area. The study
required development of a current land use/land cover data
base of Illinois, Wisconsin, Indiana and Michigan, and was
governed by the Lake Michigan Air Director's Consortium.
This data provided source information to geographically
locate ozone emissions and to estimate biogenic emissions
from a variety of vegetative sources.
Due to the legal ramifications of this project, the Consortium
required that the land use/cover classification be completed
within a 10 month period. This time line allowed a maximum
of four weeks, per scene, for all land use/cover processing
and accuracy assessment. For this reason it was necessary to
explore the use of ancillary data as a resource for breaking the
data into logical components that could be analyzed
independently.
It is commonly known that certain urbanized and non-
urbanized classes reflect visible and infrared light in a very
similar spectral signature. Previous experience had
determined that separating these areas would minimize any
possible confusion of these classes. For example, quarries,
bare asphalt and beach usually reflect light similarly, therefore
they were separated before automated classification
techniques were implemented.
The ancillary data used for this project were grouped into
three categories: aerial imagery, analog maps, and digital data
sources. These digital data sources included four different
types of digital data:
USGS 1:100,000 scale Digital Line Graph (DLG)
*1:250,000 Land Use and Land Cover Data (LUDA)
*1:250,000 scale Digital Elevation Model (DEM)
* United States Bureau of Census 1990 Post-Census
TIGER data
Aerial photography included the use of two types of aerial
photography and one type of slide film. Aerial photography
included photography from the National High Altitude
Photography (NHAP-2) program and National Aerial
Photography Program (NAPP). This photography was
acquired to provide as much coverage as possible while
adhering to budgetary constraints. The photography served a
dual purpose: first, to provide a data source for initial
classification accuracy, and second, to serve as a source of
ground truth when computing the final land use and land
cover classification accuracy assessment. The aerial coverage
was divided into two data sets. The first set was used to
extract signatures and perform initial accuracy assessments.
The unused photography was set aside to perform the final
accuracy assessments.
As an enhancement to the national photography acquired,
United States Department of Agriculture - ASCS 35mm color
compliance photography was ordered as well. This film
proved valuable as a source of information to support the
aerial photography. In addition, ASCS-578 and ASCS-
156EZ crop report information was also available for this
area. Individual county ASCS offices provided lithographed
"photomaps" delineating each field and specific crop type for
any desired year. Because of the dynamic nature of
agricultural practices (i.e., crop rotation), this information
provided an accurate representation of crop types for various
areas. This information greatly enhanced the ability of the
106
analyst to identify crop type and increase classification
accuracy.
The LMOS project required that a significant amount of TM
data be processed quickly and accurately. Therefore it was of
great importance that the methodology for the classification be
established and adhered to at the onset of the project. The
Consortium requested that an initial test classification be
completed which set the methodology for the complete 10
month study. This classification effort was unique in that a
very complex set of pre-classification procedures were
established to allow the image analyst to immediately begin
processing. The data were processed by project teams with
assigned tasks for completion of various phases of the
project.
Pre-processing included tasks as simple as loading data onto
the computer system and analyzing each band for data
anomalies and cloud cover. Each data set was verified for
acceptability prior to pre-processing. Once the data were
verified, they were then clipped to data boundary limits and
separated into urban and non-urban data sets using Census
TIGER political boundaries or Place Boundaries. Although
TIGER Place Boundary information is very general, it allows
for the accurate separation of a majority of the data into urban
versus non-urban data sets. The non-urban areas were also
carefully checked for small urban areas which would not have
been represented in the TIGER files. These small urban areas
were separated with on-screen "heads up" digitizing using the
ERDAS-ARC/INFO Live Link?M,
Once the data were separated into urban and non-urban sets,
the data were processed into principal components using a
standard Principal Components Analysis (PCA) algorithm.
The PCA was used primarily as a data reduction technique to
eliminate redundant spectral information, thereby reducing the
amount of data and speeding computer processing time.
When the principal components analysis was completed, a
varimax rotation was applied to the data. The varimax rotation
manipulated the transformation coefficients to correlate more
closely with specific bands in the original TM data. This
allowed the analysts to more easily interpret what a specific
component band represented.
After the data sets were separated and the principal
components analysis completed, the data were processed
through the ERDAS software program ISODATA (Iterative
Self Organizing Data Analysis Technique). ISODATA
generates a set of mean vectors and covariance matrices for
each distinct spectral cluster. This unsupervised classification
algorithm was used to derive a set of clusters which
represented general features within the data set. The clusters
were then used by the analyst to determine and refine manual
signatures used in the final supervised classification.
This unique pre-processing classification methodology
allowed for a great deal of repetitive process work to be
completed prior to analysis by a professional. While other
scenes were in the classification phase of the project, the pre-
processing was completed. The image analysts were therefore
able to move from one scene to the next with little distraction,
establishing a tight progress cycle.
The final project classification utilized numerous levels of
ancillary information. The addition of this information
provided an excellent opportunity to utilize the latest
technologies in GIS modeling. The GIS modeling package,
GISMO'M, was used to assure that various procedures were
performed under consistent conditions each time the process
was run. This allowed the project teams to more quickly
complete multiple GIS processes in an efficient manner. In
addition, use of this model assured that scenes matched in
overlap areas.
Post-classification techniques were primarily GIS modeling
functions using much of the ancillary digital information
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