Warnell GIS and Spatial Analysis

GIFF Data:

• GIS base data for each county in Georgia
• NAIP2007 (1-meter pixel), NAIP2006 (2-meter pixel), NAIP2005 (2-meter pixel)
• DOQQ99:  color-infrared, good for finding wet areas
• Mapped to your 'P' drive when you log into a Warnell lab computer (P:/GA/County/)
• <more>

NRCS Geospatial Data Gateway:

• NAIP imagery and other GIS data for the nation
• http://datagateway.nrcs.usda.gov
• Click on the 'Get Data' link in the upper-left to get started
• <more>

Whitehall GIS Data:

• (L:) /FORS4010/Lab/Silv Prescription Project/
• Copy the 'New Whitehall GIS Project' to your thumb drive or your network space
• Rename the folder, something without SPACES
• Contains:
  • CIRIimagery (DOQQ99):  color-infrared orthos from 1999
  • DOTHighway:  georeferenced road maps, good for location maps
  • DRG (Digital Raster Graphics):  scanned and georeferenced USGS 7.5 minute topographic maps
  • Elevation:  pixel values, in these data, represent elevation in meters
  • OtherGIS:  Whitehall stands, boundary, roads, streams, soils
  • NAIP_Imagery

Getting Started:

• Open the 'Whitehall.mxd' sample ArcGIS project (stored in the folder you copied over)
  • The compartment boundaries you see, values stored in the 'compartmen'field in the attribute table, are from last semester, they may not align with those assigned this semester.
• Create a new shapefile only showing the stands on your site
  • select the stands (select feature button) that fall within your study area
  • right-click on the theme name in the Table of Contents > data > export data
    • in the dialog, specify a name for the new shapefile
    • make sure 'selected records' is specified
    • hit OK to save those selected polygons as a new dataset
• Edit the polygons if needed
  • Load the Editor toolbar (right-click in gray area > select 'Editor')
  • Start editing your new shapefile (editor > start editing)
  • Specify your newly created shapefile as the 'Target'
  • To delete polygons:
    • select the polygon and hit the Delete button
  • To cut polygons:
    • set the TASK to 'Cut Polygon Features'
    • select the polygon(s) you want to cut
    • grab the pencil (sketch) tool
    • first click MUST be OUTSIDE of a selected polygon
    • digitize the new boundary
    • last double-click MUST be OUTSIDE of a selected polygon
  • To append polygons:
    • set the TASK to 'Auto-Complete Polygon'
    • grab the pencil (sketch) tool
    • first click MUST be INSIDE one of the polygons
    • digitize the portion of the boundary that lies outside of the existing polygons
    • last double-click MUST be INSIDE one of the existing polygons
  • Stop editing the shapefile (editor > stop editing)

Attributing Polygons:

-----Method #1-----

• Open the attribute table (right-click on the theme name > open attribute table)
• Add a new field (options > add field)
  • Specify the field name, type, etc
  • You can't add a new field to an attribute table when you are in edit mode, so if you're currently editing something, stop editing (editor > stop editing)
• Select a record (the associated polygon is selected) or select a polygon (the associated record is selected)
• Right-click on the field header and select 'Field Calculator'
• Type the attribute value in the Field Calculator dialog
  • text must be enclosed by a quote ( " )
• Repeat from the 'Field Calculator' step for each stand
• Repeat from the 'Add New Field' step for each attribute

 -----Method #2-----
You can also do a table join to attach all of the field data to the shapefile's attribute table. This is what you have to do:

In Excel

• Enter your field data into an Excel spreadsheet
• The first row must contain field names (NO spaces in the name)
• One of the fields must contain a stand identifyer whose values are identical to those seen in the shapefile's attribute table (I will assume you will use a textual ID, something like "stand1", "stand2", ...)
• The remaining columns contain the information you collected in the field
• You can only have 1 row in the Excel spreadsheet for each polygon (if you have 10 polygons, then your spreadsheet should only have 10 rows + 1 containing the headers)
• Save the spreadsheet and close Excel

 In ArcGIS

• Add a field to your shapefile that matches the type of the stand identifyer field in Excel (if your ID's are "stand1", "stand2", then your type is 'Text'; if they're 1, 2, 3 then your type is 'short integer')
• Attribute the polygons EXACTLY as you did in the Excel spreadsheet
• Unselect ALL records in the attribute table (unselect all polygons)
• Load the XLS (Add Data > double-click your spreadsheet > select your worksheet) 
• Right-click on the theme name > Joins & Relates > Join
• In the Join Data dialog, specify:
  • Join attributes from a table
  • Step 1.  the stand identifyer field in your shapefile
  • Step 2.  your spreadsheet you just loaded
  • Step 3.  the stand identifyer field in your spreadsheet
  • Hit OK
• View your attribute table (you may have to close it and then reopen it).  You should now see the information from your spreadsheet shown in the attribute table.
• If you don't see the Excel info in your attribute table,
  • Right-click on the theme name > Joins & Relates > Remove Joins > Remove All Joins
  • Check the stand identifyer fields in your Excel spreadsheet and attribute table.  Are they Exactly the same?  Are they the same type (numeric or text)?

 Displaying Colors Based on an Attribute

• Right-click on the theme name > Properties
• Select the Symbology tab
• Click on Categories
• In the Value Field, select the field on which you want to base the colors
• Click Add All Values
• Hit OK
• <more>

 Answers to some common ArcGIS questions...