Intro. To GISPre-Lab
Spatial AnalysisApril 1st , 2013
Spatial Analysis
• The application of operations to coordinate and related attribute data
• Maps are great, but this is the real power of GIS
• Spatial analysis is used to explore or solve a problem using a variety of geoprocessing tools
Calculate Geometry• Length, Area, or
X,Y coordinates• Choose coordinate
system of source or data frame
• Pick units of measurement
• Make sure field has units in the name
Types of Analysis
Layer 1
Function 1 Layer 2
Function 2 Layer 3
Function
Layer 2
Layer 1Layer
3
Dissolve Tool– Similar to the merge function in Editor
toolbar
Dissolve Tool
• Input Features• Output Feature Class• Dissolve field(s)
(optional)• Statistics (optional)
• Create multipart features (optional)
Buffering• Buffering creates a polygon using a
specified distance from a point, line, or other polygon
Buffer Tool
• Input Features• Output Feature
Class• Distance– Linear unit (pick
units)– Field (attribute table)
• Side/End type• Dissolve Type
Buffer application• 500 ft.
buffer applied to houses
• Buffer overlaps transfer station
Multiple-Ring Buffer• Creates buffers for many distances at
once• Dissolve option makes them non-
overlapping
Near Tool
• Calculates distance from input features to nearest feature in other layer(s)
Near Tool• Output has field with ID
and distance of feature
• Multiple near layers can be calculated at once
• Options to include:– Location (X,Y)– Angle (degrees)
Intersect
• Polygons split at feature boundaries of both datasets
• Only overlapping areas are kept
• Attribute tables are combined in output
Identity• Similar to
intersect but input features are not clipped
• Features split along identity polygon edges
• Attribute tables are combined in output
Union• Like Intersect
but both input and union features are retained
• Output features have attributes from both input and union layers
Intersect / Identity / UnionWhich function is which?
