GIS SOLUTION
Spatial Analysis - answer Spatial Analysis is the process by which we turn raw
geographic data into useful information, and
reveal patterns not immediately obvious
Effective Spatial Analysis - answer Effective Spatial Analysis requires an intelligent
user, not just a powerful computer
Applications of GIS - answer§ Location
§ Quantity
§ Patterns
§ Trends (Temporal Aspect)
§ Conditions & Relationships
§ Implications (Planning for the future)
Basic Principles of Spatial Analysis - answer Basic Principles
1. Measurements
2. Scope
3. Queries
4. Proximity Functions
5. Geoprocessing
1) Measurements in GIS - answerSimple numerical values that describe aspects of, or
simple properties of geographic data, such as length, area, shape,
OR, relationships between pairs of objects, like distance or direction
Distance: Different calculation methods based on data format
§ Vector
§ Distance
§ Euclidean Distance
§ Raster
§ Distance
§ Euclidean Distance
§ Manhattan Distance
§ Proximity
2) Scope - answerThe geographical extent or area of the input data
used to determine the values at output locations
Characterization of Scope
§ Local
§ Neighborhood
,§ Global
3) Queries - answerPrimary method of data
retrieval
§ Allow us to create new
information, but doesn't
change the older/existing
information
§ Type of Queries
§ Aspatial (non-spatial)
§ Set Algebra <, >, =, <>...
§ Boolean Queries OR, AND, NOT
§ Spatial
§ Adjacency
§ Containment
4) Proximity Functions - answer§ Buffers: The creation of a zone(s) of interest (inclusion
or exclusion) around an entity
§ Spatial Join
§ Thiessen Polygons
5) Geoprocessing (Spatial Data Integration) - answerSpatial Data Integration is also
known as
Geoprocessing
Geoprocessing involves using data from one or
more spatial layers and integrating it to form a new, single layer
Clipping - answerThis process creates a new layer by using a polygon layer (or selected
polygons from a particular layer) as a cookie cutter on a point, line, or polygon shapefile.
The output layer
contains information from Layer A only. Layer B is only used to define the new boundary
Intersect - answerThe intersect method preserves only those features falling within the
spatial extent common to both layers. The features of the input layer are intersected or
sliced by the intersect layer. The attribute data from both layers are included in the new
layer's attribute table.
Dissolve - answerDissolving features in a layer coalesces features that have the same
attribute value. This tool is extremely important if you are trying to create a new
shapefile, a file with a coarser layer of geography than your starting files.
Union - answerUnion creates a new layer by combining two polygon layers. The new
layer has data and shapes from both layers, including their intersection.
, Merge - answerUsing merge is similar to union; a new layer is created from multiple
layers but their features are not intersected. Merge allows you to combine the features
from two or more layers
of the same geometric type.
Spatial Overlay Analysis - answerOverlays are the combination of spatial and attribute
data from two or more spatial layers
Polygon Overlay - answer§ Here the overlay of two layers produces four
distinct polygons.
§ The output polygons has attribute properties from both parent layers
Intersect & Union for Overlay - answerThe intersect method preserves only those
features falling within the spatial extent common to both layers. The features of the input
layer are intersected or sliced by the intersect layer. The attribute data from both layers
are included in the new layer's attribute table.
Union creates a new layer by combining two polygon layers. The new layer has data
and shapes from both layers, including their intersection.
In fact, union differs from intersect only by the fact that all the features of both layers are
included in the resultant layer, including those features that did not overlap.
Point in Polygon - answer§ Polygon to point: Adding to the attribute properties of a point
feature based on the polygon in which it resides
§ Point to Polygon: summarizing the attributes of all points within a given polygon
Spatial Estimation: Spatial Interpolation - answerThe procedure of estimating the values
of properties at unsampled sites within an area covered by existing observations
Spatial data usually are:
§ Stratified (a)
§ Random (b)
§ Patchy (c)
§ Adaptive (d)
Interpolation - answerEstimating the value of properties at un-sampled sites within the
area covered by existing observations
§Widely used for:
§ Climate Data
§ Predictive stats
§Data should be:
§ Point files
§ Interval or ratio
§Keep in mind:
§ Tobler's first law - data must be spatially auto-correlated
§ Only works for continuous variables
Spatial Analysis - answer Spatial Analysis is the process by which we turn raw
geographic data into useful information, and
reveal patterns not immediately obvious
Effective Spatial Analysis - answer Effective Spatial Analysis requires an intelligent
user, not just a powerful computer
Applications of GIS - answer§ Location
§ Quantity
§ Patterns
§ Trends (Temporal Aspect)
§ Conditions & Relationships
§ Implications (Planning for the future)
Basic Principles of Spatial Analysis - answer Basic Principles
1. Measurements
2. Scope
3. Queries
4. Proximity Functions
5. Geoprocessing
1) Measurements in GIS - answerSimple numerical values that describe aspects of, or
simple properties of geographic data, such as length, area, shape,
OR, relationships between pairs of objects, like distance or direction
Distance: Different calculation methods based on data format
§ Vector
§ Distance
§ Euclidean Distance
§ Raster
§ Distance
§ Euclidean Distance
§ Manhattan Distance
§ Proximity
2) Scope - answerThe geographical extent or area of the input data
used to determine the values at output locations
Characterization of Scope
§ Local
§ Neighborhood
,§ Global
3) Queries - answerPrimary method of data
retrieval
§ Allow us to create new
information, but doesn't
change the older/existing
information
§ Type of Queries
§ Aspatial (non-spatial)
§ Set Algebra <, >, =, <>...
§ Boolean Queries OR, AND, NOT
§ Spatial
§ Adjacency
§ Containment
4) Proximity Functions - answer§ Buffers: The creation of a zone(s) of interest (inclusion
or exclusion) around an entity
§ Spatial Join
§ Thiessen Polygons
5) Geoprocessing (Spatial Data Integration) - answerSpatial Data Integration is also
known as
Geoprocessing
Geoprocessing involves using data from one or
more spatial layers and integrating it to form a new, single layer
Clipping - answerThis process creates a new layer by using a polygon layer (or selected
polygons from a particular layer) as a cookie cutter on a point, line, or polygon shapefile.
The output layer
contains information from Layer A only. Layer B is only used to define the new boundary
Intersect - answerThe intersect method preserves only those features falling within the
spatial extent common to both layers. The features of the input layer are intersected or
sliced by the intersect layer. The attribute data from both layers are included in the new
layer's attribute table.
Dissolve - answerDissolving features in a layer coalesces features that have the same
attribute value. This tool is extremely important if you are trying to create a new
shapefile, a file with a coarser layer of geography than your starting files.
Union - answerUnion creates a new layer by combining two polygon layers. The new
layer has data and shapes from both layers, including their intersection.
, Merge - answerUsing merge is similar to union; a new layer is created from multiple
layers but their features are not intersected. Merge allows you to combine the features
from two or more layers
of the same geometric type.
Spatial Overlay Analysis - answerOverlays are the combination of spatial and attribute
data from two or more spatial layers
Polygon Overlay - answer§ Here the overlay of two layers produces four
distinct polygons.
§ The output polygons has attribute properties from both parent layers
Intersect & Union for Overlay - answerThe intersect method preserves only those
features falling within the spatial extent common to both layers. The features of the input
layer are intersected or sliced by the intersect layer. The attribute data from both layers
are included in the new layer's attribute table.
Union creates a new layer by combining two polygon layers. The new layer has data
and shapes from both layers, including their intersection.
In fact, union differs from intersect only by the fact that all the features of both layers are
included in the resultant layer, including those features that did not overlap.
Point in Polygon - answer§ Polygon to point: Adding to the attribute properties of a point
feature based on the polygon in which it resides
§ Point to Polygon: summarizing the attributes of all points within a given polygon
Spatial Estimation: Spatial Interpolation - answerThe procedure of estimating the values
of properties at unsampled sites within an area covered by existing observations
Spatial data usually are:
§ Stratified (a)
§ Random (b)
§ Patchy (c)
§ Adaptive (d)
Interpolation - answerEstimating the value of properties at un-sampled sites within the
area covered by existing observations
§Widely used for:
§ Climate Data
§ Predictive stats
§Data should be:
§ Point files
§ Interval or ratio
§Keep in mind:
§ Tobler's first law - data must be spatially auto-correlated
§ Only works for continuous variables
