Title: Merging More Than One Theme into a Common Theme

Date: June 4^th, 2001

Purpose: The purpose of merging themes is to combine features that have something in common with each other into one common theme. It allows for complex themes to be created or the creation of new themes, using existing themes with similar field attributes.

Extensions Required: Geoprocessing Wizard or XTools

Procedure:

· To merge two or more themes, the themes must be of the same shape type (point, line, or polygon) and be loaded into the current view.

· Load the Geoprocessing Wizard or XTools extensions into ArcView

· Make sure the themes you want to merge are of the same shape type and are displayed in the view.

Using Geoprocessing Wizard

· To merge two or more themes, click on File – Geoprocessing Wizard

· In the geoprocessing opttion window, click on the Merge Themes Together radio button.

· Click on Next

· Select at least two themes to merge in the option window (must be of same shape type)

· Choose theme with the fields you want use for the merge (select on of the files you are using).

· Select output file with appropriate path and name (d:\temp\file_folder_name\file_name.shp)

· Click on Finish to merge the themes and to create a new shapefile with the combined features.

· When asked if you want the new shapefile to be added to the existing View, select Yes to load new theme into the view.

· Make note of the new file name and its location for future use.

Using XTools

· To merge two or more themes using the XTools extension, be sure that the XTools is loaded.

· Click on XTools in the Menu Bar and Select Merge Themes

· When asked for Input Theme, select one of the themes you want to merge and click OK

· Then, select themes you want to merge the input theme with (can choos more than one theme to merge with input theme by holding down the shift key and clicking on all appropriate files).

· Click on OK

· Give the newly merged theme a new name, making sure you save it to an appropriate folder with an appropriate name.

· Click on OK to create merged file (the new file will automatically be displayed in the current view).

· To view new theme, click on its check box to make it active.

Conclusions:

By utilizing the merge features of Geoprocessing Wizard and XTools one can create new shapefiles using existing data as a source. The purpose of merging is to combine or append features of two or more themes into a single theme. Data is preserved during the merge if the fields used are of the same name, nature, and data type. Merging themes saves time in digitizing and database development, if one were to want a new theme created based from existing data.

Created by Chris Connell and Andy Freed, Geography 452: Advanced GIS Class.