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ver in the region
1sing supervised
re. National map
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tion and allow
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ized roads and
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(Environmental
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e created using
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ty) would be
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milar ecoregions
93; King, 1994;
1ayas and Pope,
this study the
fication in this
s still untested.
il 1994 from the
search (INPE),
field survey was
eavy cloud cover
nber 1993, four
a second image
etection analysis
(not yet attempted). Bands 2, 3, 4, 5 and 7 were used
for our analyses.
We chose to utilize supervised classification
methods because of several apparent advantages over
unsupervised or manual approaches. Supervised
methods:
e encouraged compatibility with existing ecologic
literature and mapping efforts in the ecosystem,
e facilitated objective classification and
compatibility with future classifications, and
e ensured that ground truthing would play an
integral role in the study.
3.1 GPS and Other Field Measurements
Global positioning system (GPS) receivers
collected ground location information during field
work, which was conducted during January and
February 1994. Three types of location data were
needed:
® control points surrounding the study area for
georeferencing the images,
© training plot locations for the supervised
classification, and
€ road and tourist attraction locations for map
production and orientation purposes and for the
accessibility-deforestation analysis.
Collection of the control points, road, and
tourist attraction information was done using a six
channel Pathfinder Pro (Trimble Navigation Ltd.)
GPS receiver and data logger unit, which stored up
to 1 megabyte of readings exportable as geographic
objects into GIS format. This unit was brought from
the United States. A similar six channel unit without
the data logger (Trimble Pathfinder Basic Plus) was
used for the training site locations, where simple
point locations were sufficient. This receiver was
rented for the field season from a vendor in Rio de
Janeiro.
All readings were differentially corrected
after downloading to a personal computer, using data
from a survey-grade base station set up at FUPR in
Curitiba especially for this field work.
Two forestry students were hired for January
and February, when university classes were closed
for the summer, to collect and enter the field plot
data. Their work was supplemented by two
additional employees of SPVS who kept the rented
GPS receiver in use during weekends and holidays.
Two employees from the Superior National
Forest in Minnesota experienced in GPS surveying
joined the team for the first half of the field season to
establish GPS procedures and train the field crews on
their use. They also were responsible for establishing
73
the locations of the control points, roads, and most of
the tourist attractions. Notes and sketches from field
books were supplemented by brief notations typed
into the data logger. These provided digital
documentation of the data collection process which
was carried through into the GIS as comment fields.
With the GPS antenna mounted on a
vehicle's roof, we digitized road segments in
streaming mode by driving them and collecting
readings every 10 seconds. Each road segment was
terminated by a point feature to ensure solid location
readings at intersections and road ends. Roads were
classified by surface quality, and time stamps
embedded in the GPS readings provided indications
of relative travel speed.
Eight useable control points were established
around the APA, principally road intersections or
bridges, and three more were added later from
topographic maps. As with other point features, each
location consisted of at least 180 individual readings,
which after differential correction were averaged
together. All GPS output files were plotted and
visually examined for outliers which were deleted,
although such outliers were rare. Differential
correction and other GPS postprocessing was
performed using the PC program PFINDER (Trimble
Navigation, Ltd.).
For the training plots we designed a data
entry form using a simple database program,
providing both paper-based forms for field use and
an electronic form for data entry and analysis.
Several types of measurements were taken at each
site, including variables describing basic descriptive
information, attractiveness for ecotourism, and
reliability for image classification. This last group
included present cover type, nearby cover types in
each of four directions, and indications of recent
change in cover type. Estimated locations and times
were also recorded to provide redundancy with GPS
data for later error checking. Forms were tested in
the field and revised several times.
Prior to field work we selected twenty
categories of land cover, based on the literature
(Roderjan and Kuniyoshi, 1988), expert judgment,
and preliminary field work. These included an urban
category, seven agricultural categories, six stages of
dense forest (floresta ombrofila densa) regrowth or
disturbance, plus six additional categories of forest
or herbaceous communities. We intentionally
selected more categories than we expected to
ultimately resolve from the images to encourage
collection of a diversity of conditions and to allow
subsequent flexibility in combining categories during
the classification process.