GEOG 4813: GIS
Building Your Own Geodatabase Using ArcGIS
Part 1: Creating a geodatabase
in ArcCatalog
Developing entirely new maps using on-screen digitizing
to create spatial features (such as points, lines, and polygons) is a vital
GIS capability. ArcGIS provides a useful, but proprietary, spatial
data format for this task called a geodatabase. Chapter 14 in
"Getting to Know ArcGIS Desktop" provides a useful introduction to geodatabases,
and Chapter 15 gives instructions for on-screen (or "heads-up") digitizing,
but both chapters assume that the user begins with an existing geodatabase.
This tutorial will focus on beginning from "scratch" to build an entirely
new personal geodatabase [There are "multiuser" geodatabases, too, but these
require ArcSDE which does not function within our ArcView 8.3 environment.]
We'll use a DOQQ of Tahlequah (specifically i:/ziehr/Exercise4/35094h83.bil)
as our source reference for on-screen digitizing. There are a lot
of steps involved, but follow along carefully and think conceptually and
you'll be successful.
- Start ArcCatalog
- In the ArcCatalog tree (left window) navigate to the folder in which
you will save your geodatabase (for example, your L: drive). Right
click on the folder and choose New -- Personal Geodatabase.
- Change the name of the new personal geodatabase. The default
is "New Personal Geodatabase.mdb" so make it something that will remind you
of what is contained in the file. For this class be sure to begin
the file name with your last name for any file that will be turned
in. Be sure to leave the .mdb extension.
- Right click on the newly-created file in the ArcCatalog tree. Choose
New -- Feature Class.
- In the New Feature Class dialog enter a name (with NO spaces) and
press the Next> button. For example, Streets would be an appropriate
name for line features consisting of streets in Tahlequah.
- Accept the Default for "Specify the data storage configuration"
response and press Next>.
- In the next dialog click on the word "Shape" in the Field Name column.
The following screen will display which shows the Field Properties
of the "Shape" field. You will be setting the "Geometry Type" and the
"Spatial Reference" for the "Shape" field.
- Click on the word "Polygon" next to the "Geometry Type" in the "Field
Properties" box (Polygon is the default geometry type). A drop-down
box appears; select the appropriate geometry type for your "Shape" field.
For example, you would select "Line" if your "Shape" field was for
streets.
- Next click the ellipse (...) to the right of the "Spatial Reference"
row in the "Field Properties" box. A "Spatial Reference Properties"
dialog box will be displayed. Click "Select".
- A "Browse for Coordinate System" box will display.
- Double-click on "Projected Coordinate Systems" and select "Utm"
for our purposes (recall we'll be using a DOQQ as a reference for our on-screen
digitizing).
- Then choose "Nad 1983" since our DOQQ is based on this datum.
- Then choose NAD 1983 UTM Zone 15N.prj since our DOQQ of Tahlequah
is in the Northern Hemisphere of UTM Zone 15. Click Add.
- Details about the NAD 1983 UTM Zone 15N projections are then displayed.
Click on the X/Y Domain tab.
- Enter the minimum and maximum X and Y coordinates (UTM coordinates
obtained from the Extent in Layer Properties for the DOQQ--35094h83.bil)
and let the system set its own "Precision" based on these extreme values.
Press OK.
- Click the first blank cell in the Field Name column and add any attribute
fields that you will want in the attribute table of your spatial features
(such as Street_Name for your Street file). Be sure NOT to use spaces
in the Field Name.
- Click the empty Data Type cell next to the new field name and select
the appropriate data type (for example, "text" for the Street_Name field).
Add any additional new fields (and their data types) that you will
need; perhaps such things as type of street , number of lanes, type
of surface material, and/or year built. Press Finish.
- You've now got a new personal geodatabase ready to receive spatial
data. In essence you set the specifications for the data, but currently
there is still no data in the file. Notice that in the ArcCatalog
display window you now have the name of your new feature class, "Streets."
- Go to <http://arapaho.nsuok.edu/~ziehr/courses/geog4813/Building_Your_Own_Geodatabase_Using_ArcGIS-Part2.html>
to continue this exercise. In that section you'll be using ArcMap
for on-screen digitizing.
Last revised April 15, 2004.