Geodatabase and Domain Creation

Introduction

                A geodatabase is a great tool to use for creating and maintaining map documents in ArcGIS. In the future we will be making a microclimate map of the University’s campus. Features of this map will be collected from the field and stored in the geodatabase. In the geodatabase are feature classes which are were all the separate features are stored i.e., temperature, notes, wind, and snow depth. The geodatabase is an easy and efficient way to store information due to rules that exist to allow for less errors and more accurate information.

Part 1: Class Work

                In class we laid out the essentials for creating and using domains. Domains are associated with field types and allow only certain types of attributes to go into a field type. When creating a field the type of data that it uses is associated with the domain. In the domain there are numerous types of data that can be used. The ones that were suggest for class are short and long integer, float, and text. These field types all have different attributes to them short and long integer, and float all have to do with numerical values. Short integer uses numbers that are in a range from -32, 768 to 32, 767, long integer ranges from -2,147,483, 648 to 2,147,483,647, and float allows for decimals places. Text entails exactly what it states, the use of text. When it comes down to it short integer is recommended over long because of storage usage. In a domain a range of can be set which eliminates errors. For example, if the range is from 1-10 a value of 11 cannot be entered or even more so relevant a value of 80, which can happen because of an accidental finger movement. The domain will pick up this error and not allow for completion of the field.

                For this exercise we were given a set of fields to use. These fields are to be used in the microclimate map that will be made in the future. These fields were group number, notes. Relative humidity, snow depth, temperature, dew point, time, win azimuth, wind direction, and wind speed. As one could discover most of these are numerical values and use short integer. These features will be collected in the field using ArcPad which is an ArcGIS extension that is used to store data in respected feature classes. This data is stored according to its domain. For example, snow depth has a short integer field type which means that it cannot be entered as a text type or there will be an error.

Part 2: Geodatabase and domain creation

                To create a geodatabase the first step is to open a new document in ArcMap or ArcCatalog, both will work. Once that is done navigate to the folder you wish to locate the geodatabase in. Right click the folder, choose new, file geodatabase, and name it something that relates to your study interest. For this exercise I named my geodatabase mc_fabianev.

Figure1: Creation of a Fiel Geodatabase in ArcMap

The next step is to create your domains. Right click your newly created geodatabase and select Properties, in the Database Properties window click the Domains tab. Here is where the Domain Names and Description is set. A certain domain name would be Temp and its description would be something along the lines of, “Temperature in degrees Fahrenheit”. Under the Domain Name table is Domain Properties. Here is where our rules come in. For the classes the recommended Field Types are Short Integer, Float, and Text. This is also where the range is set if the Domain Type is a Range Domain. The other Domain Type is Coded Values which are commonly used with Text Domains. When finished hit apply to create all the Domains

Figure 2: Creation of Domains in Arc. Domains are the field attributes used to create Feature Classes

After the creation of Domains the process of creating a Feature Class is started. Right click the geodatabase, select New and then Feature Class. A window called New Feature Class will pop up here you name your Feature Class. Name it something appropriate, mine is micro_fabian_prj. Then select the type of feature. Common features are point, line, and polygon. For the purpose of the exercise point was chosen. Click next which will lead to the coordinate system selection. For this exercise NAD 1983 UTM Zone 15N fits well because of the location of the field exercise. Click Next. XY Tolerance is unchanged. Click Next. Default database storage remains unchanged, use the default option. Click Next. We are finally out our field creation step. In the Field Name column enter the fields that are to be created. In the Data Type column next to it is where our Domains come in. Selecting the field type will relate it to the Domain Type. Fill out all the appropriate fields and the completion of the feature class is complete when Finish is clicked.

Figure 3: Creation of Feature Classes in Arc

To import the Raster base image into the geodatabase right click the geodatabase > Import > Raster Datasets > Folder where Raster is located > Add.

Figure 4: Importing a Raster Image to a Geodatabase

Conclusion

       The creation of geodatabase and domains helps the collection and application method of field and GIS much easier. By having domains errors are eliminated allowing for a smoother process when data entry begins.