GIS OverlayGIS Overlay

Getting to the “where is?”Getting to the “where is?”

Distance 1.... bufferingDistance 1.... buffering

Creates a distance from a featureCreates a distance from a feature Works with points lines and polygonsWorks with points lines and polygons Legal descriptions... Nature rarely pays Legal descriptions... Nature rarely pays

attention to specified distances...attention to specified distances...• Streams flood by elevation, not distance from Streams flood by elevation, not distance from

the streamthe stream• Eagles hunt where the food is, not within a ¼ Eagles hunt where the food is, not within a ¼

mile circle of their nestmile circle of their nest• Volcanoes erupt based on internal mechanics Volcanoes erupt based on internal mechanics

influenced by topography, not by neat rings of influenced by topography, not by neat rings of hazardhazard

Buffer....Buffer.... The buffer wizard...The buffer wizard... The ArcGIS 8x Buffer wizardThe ArcGIS 8x Buffer wizard The ArcGIS 8x Buffer Wizard has been removed The ArcGIS 8x Buffer Wizard has been removed

from the ArcMap Tools menu, but it is still from the ArcMap Tools menu, but it is still accessible if you click Tools, click Customize, click accessible if you click Tools, click Customize, click Tools in the Commands tab, and select Buffer Tools in the Commands tab, and select Buffer Wizard. If you want to use this wizard, you can Wizard. If you want to use this wizard, you can add it to any ArcMap toolbar or pulldown menu add it to any ArcMap toolbar or pulldown menu from the Customize dialog box. You may want to from the Customize dialog box. You may want to do this to buffer graphics drawn on a map. do this to buffer graphics drawn on a map.

NOTE: In the Buffer tool, the Side Type option is NOTE: In the Buffer tool, the Side Type option is restricted to FULL and the End Type option is restricted to FULL and the End Type option is restricted to ROUND if you are using an ArcView restricted to ROUND if you are using an ArcView or ArcEditor license. Setting the Side Type to LEFT or ArcEditor license. Setting the Side Type to LEFT or RIGHT and setting the End Type to FLAT, are or RIGHT and setting the End Type to FLAT, are only possible if you are using ArcInfo.only possible if you are using ArcInfo.

This is the interface developed in Arcview 3.X Allows you to buffer only the selected features

The buffer tools....The buffer tools....

You cannot buffer selected features (unless you select features and convert them to a new data layer (shapefile)

Spatial JoinSpatial Join

Uses the ‘shape’ field to join two Uses the ‘shape’ field to join two spatial attribute layersspatial attribute layers

Works with points/lines or polygons Works with points/lines or polygons (Raster data requires another (Raster data requires another approach)approach)

From the Joins and relates tab From the Joins and relates tab

Overlay toolsOverlay tools Clip- the cookie cutterClip- the cookie cutter Erase-the eraser shieldErase-the eraser shield Intersect-keeps data from both data setsIntersect-keeps data from both data sets Union- keeps everything from every data Union- keeps everything from every data

setset Dissolve- remove internal lines based on Dissolve- remove internal lines based on

an attribute (censuses tracts inside a an attribute (censuses tracts inside a county)county)

Merge-add two spatial data sets together Merge-add two spatial data sets together (tiger files from Lauderdale and Colbert (tiger files from Lauderdale and Colbert counties)counties)

The ArcGIS 8x The ArcGIS 8x Geoprocessing Wizard Geoprocessing Wizard has been removed from ArcMap; it is has been removed from ArcMap; it is no longer provided in the product. no longer provided in the product.

Locating the 8x Geoprocessing Wizard operations in the Locating the 8x Geoprocessing Wizard operations in the ArcToolbox window ArcToolbox window

Clip— Clip— Analysis toolbox > Extract toolset > Clip toolAnalysis toolbox > Extract toolset > Clip tool Intersect— Intersect—

Analysis toolbox > Overlay toolset > Intersect toolAnalysis toolbox > Overlay toolset > Intersect tool Union— Union— Analysis toolbox > Overlay toolset > Union toolAnalysis toolbox > Overlay toolset > Union tool Dissolve— Dissolve—

Data Management Tools toolbox > Generalization toolset > Data Management Tools toolbox > Generalization toolset > Dissolve toolDissolve tool

Merge— Merge— Data Management Tools toolbox > General toolset > AppenData Management Tools toolbox > General toolset > Append toold tool

NOTE: In the Union and Intersect tools, only two inputs are allowed NOTE: In the Union and Intersect tools, only two inputs are allowed if you are using an ArcView or ArcEditor license. The ability to if you are using an ArcView or ArcEditor license. The ability to union or intersect more than two inputs is only available if you are union or intersect more than two inputs is only available if you are using an ArcInfo license.using an ArcInfo license.

X-Tools

The better way to spatial analysis in Arcview 3.X