Intro. To GIS Pre-Lab Spatial Analysis April 1 st , 2013

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?