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Building geodatabase in ArcMap 10 Desktop

Those step-by-step tutorials are created for novices in GIS. By design, they are very simple and provide only essential and practical information to accomplish most common tasks with GIS software. For in-depth coverage of the topic, please, refer to ESRI ArcGIS Resources http://resources.arcgis.com/en/help/main/10.1/

The three primary types of datasets in GIS

Geodatabase can incorporate links to the non-spatial databases, shapefiles, images, etc. A key geodatabase concept is the dataset. It is the primary mechanism used to organize and use geographic information in ArcGIS. The geodatabase contains three primary dataset types:

  • Feature classes
  • Raster datasets
  • Tables

Creating a collection of these dataset types is the first step in designing and building a geodatabase. Users typically start by building a number of these fundamental dataset types. Then they add to or extend their geodatabases with more advanced capabilities (such as by adding topologies, networks, or subtypes) to model GIS behavior, maintain data integrity, and work with an important set of spatial relationships.

Geodatabase elements

All GIS users will work with three fundamental dataset types regardless of the system they use. They'll have a set of feature classes (much like a folder full of Esri shapefiles); they'll have a number of attribute tables (dBase files, Microsoft Access tables, Excel spreadsheets, DBMSs, and so forth); and most of the time, they'll also have a large set of imagery and raster datasets to work with.

Fundamentally, all geodatabases will contain this same kind of content. This collection of datasets can be thought of as the universal starting point for your GIS database design.

As necessary, users can extend their data models to support certain essential capabilities. The geodatabase has a number of additional data elements and dataset types that can be used to extend this fundamental collection of datasets. We will start with

Creating new empty geodatabase on your PC

The geodatabase is a "container" used to hold a collection of datasets. There are three types:

iFile geodatabase

  1. File geodatabases—Stored as folders in a file system. Each dataset is held as a file that can scale up to 1 TB in size. The file geodatabase is recommended over personal geodatabases.
  2. Personal geodatabases—All datasets are stored within a Microsoft Access data file, which is limited in size to 2 GB.
  3. ArcSDE geodatabases—Also known as multiuser geodatabases. Stored in a relational database using Oracle, Microsoft SQL Server, IBM DB2, IBM Informix, or PostgreSQL. These geodatabases require the use of ArcSDE and can be unlimited in size and numbers of users.

ArcGIS will continue to support personal geodatabases for numerous purposes. However, in most cases, Esri recommends using file geodatabases for their scalability in size, significantly faster performance, and cross-platform use. The file geodatabase is ideal for working with file-based datasets for GIS projects, personal use, and in small workgroups. It has strong performance and scales well to hold extremely large data volumes without requiring the use of a DBMS. Plus, it is portable across operating systems. Thus, we will create a new empty File geodatabase.

In ArcCatalog on the left navigate to the folder where you want to create File Geodatabase and right-click that folder. Select File geodatabase and give it a name.

Adding shapefile into geodatabase

Shapefiles are wide-spread containers for sharing geographical information in vector format. They can be of three types: point, line and polygon. Sample shapefile was received from collaborators and is a point vector file of worldwide weather stations with UNKNOWN projection. Lets start with

Defining geographical projection for the file:

1. In Arc Toolbox under Data Management open tool Projections and Transformations/Define Projection

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2. Select data set with unknown projection and select WGS_1984 (we have known that data set is in decimal degrees and covers the whole world, so that was a reasonable choice). Wait until you see a green check marks pop up in the low right corner signifying that operation succeeded.

 image

3. Verify that new projection is shown for the file:

image

Adding shapefile:

 

1. Now right-click the shapefile and select Export/To Geodatabase (single)

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2. On the next dialog select the geodatabase you want to import file into and give the shapefile different name.

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Depending on the size of the dataset, this might take a while to import, look for the right bottom corner to see when the import is finished. image will be running and then image. Note, that importing large data  sets might take a while – importing ~7000 point data took 3 min, but ~320000 polygons completely covering North America took more than 30 min. Large datasets are better imported directly through ArcCatalog, just open ArcCatalog from Windows Start button as a separate program and repeat steps 1 and 2 above, this way the data imported would not be drawn in ArcMap and importation process will run about 10 times faster.

Similar to shapefiles, Excel tables and georeferenced images can be imported into geodatabase through ArcCatalog.

You can load layers from the geodatabase in ArcMap one by one. The advantage of using geodatabase is that all data layers, supplemental information and geoprocessing tools are kept together in one place and can be easily used in new projects.

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References:

  1. Gina Clemmer, The GIS 20: Essential Skills, 1st ed (Redlands, Calif: ESRI Press : Distributed to the trade by Ingram Publisher Service, 2010)
  2. ESRI ArcGIS Resources http://resources.arcgis.com/en/help/main/10.1/

 

Interesting!

Interesting!