Regions in ArcINFO

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Regions in ArcINFO
Regions can handle overlapping, noncontiguous and
nested areas and makes real-world features easier
to represent and analyze. Data management is
more efficient, as each region only requires one
attribute record.
Overlapping ranges
Non-contiguous areas
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Regions in ArcINFO
Overlapping polygons - ranges for
multiple wildlife species - fires
(burned areas) through time, fire atlas data
- countries of the world through time
- managing habitats, that are not spatially
exclusive - managing different floor
plans for a building Non-planar features
- data in different planes, for example, soil
data collected at various soils depths -
geological data that overlaps at various depth
levels Noncontiguous areas - islands that
comprise the state of Hawaii as a single feature
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Regions can have VOID AREAS
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Regions may have multiple sub-classes
- A regions coverage may contain one or more
region subclasses - A subclass contains one or
more region features - Each region subclass
can be visualized as lying in its own
plane above the polygon topology. - Each
region subclass has its own set of attributes
because each subclass has its own PAT.
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POLYGONS - cannot overlap - single contiguous
area - feature class partitions space - cannot
be nested - one feature class per cover
REGIONS - can overlap - multiple noncontiguous
areas - void areas allowed - can have nested
features - many feature classes per cover
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Creating Regions ? - Regions can be created
from coordinate files or digitizing. - Regions
can be created and edited interactively using
ARCEDIT. - Regions can be generated directly
from existing coverages using points or nodes,
arcs, polygons or existing regions. - Regions
can be created from queries and logical
operations on polygon or region coverages
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in ArcINFO
REGIONPOLY converting regions to polygon
coverages POLYREGION creating regions from
polygons
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Region commands in ArcInfo, ArcPlot and ArcEdit
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. a few region commands
regionpolylist creates an INFO file that lists
the polygons that belong to each region in the
specified subclasses regionpolycount counts
the total number of regions, and regions by
subclass, for each polygon. The selected polygon
belongs to two regions, one from each
subclass regionxarea creates an output INFO
file to describe the overlap relationship between
the two regions in area and percent regionselect
selects a set for polygons or regions through
Boolean selection of attribute values of polygons
or regions from multiple subclasses regionquery
creates new regions based on the attribute values
of input region or polygon layers and aggregates
regions according to specified attribute items.
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Example of fire-atlas data from the Selway
Bitterroot Wilderness
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Potential Vegetation Types

• Western redcedar
• Douglas-fir
• Grand Fir
• Lower Subalpine Dry
• Lower Subalpine Moist
• Upper Subalpine Dry
• Upper Subalpine Moist
• Rock/Alpine/Barren Land

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Fire Eras
Pre-Modern Suppression Prior to 1935
Modern Suppression 1935 - 1974
Wildland Fire Use 1975 - 1996
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• Changes within the fire eras
• Fire frequency
• Severity

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Fire frequency
NaExtremely infrequentVery infrequentInfrequent
FrequentVery frequent
Current Fire Regimes 1995, ICRB
Historic Fire Regimes 1900, ICRB
Fire Regime The nature of fires occurring over
an extended period of time -(Brown, 1995)
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Fire regimes have been described with the help of
Digital Fire Atlases and Aerial Photo
Interpretation
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Results Fire Severity .by Casey Teske
Stand Replacing Non-Lethal Mixed
Unknown
Area (Ha)
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examples of how to use regions
Create a map showing how many times each polygon
in the Selway-Bitterroot regions coverage has
burned between 1880 and 1996. Hint use the
REGIONPOLYCOUNT command What is the average
area burned per year within the three fire
eras - Pre-modern suppression 1880 -
1934 - Modern suppression
1935 - 1974 - Wildland fire use 1975 - 1996
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