#geodatabases

Download designing geodatabases for transportation

I am using Esri's virtual campus training to gain experience with geodatabases. This post will summarize general concepts that I learned, challenges I encountered with ArcGIS (hopefully with solutions as well) and any key terms defined through this learning experience. 

What is a geodatabase?

There are many different types of data formats that are compatible with GIS. However, geodatabases are the native form for data storage and provide advantages such as all data is centralized, ease of data migration, high data integrity, and multiple layers of images can be displayed as one.

The three basic types of geodatabase are personal, file, and multiuser. As the names suggest, personal geodatabases are smaller and typically used for one person projects. Where as file and multiuser geodatabases are much larger and allow multiple people to edit a database at the same time.

When you are building a geodatabase from scratch you must first design the outline/structure that the data will reside within. Think of this like the blueprint for your geodatabase because it outlines all the different areas you will need to fill with information. The blueprint will include feature classes, feature datasets, table/nonspatial data and stand along features (whatever it is that best presents the question you are answering with this ArcMap). 

Image source

Next step: putting data into your blueprint. The commonly accepted forms of data: CAD, dBASE, INFO tables, Coverages, Shapefiles, Text files, and raster. Excel files are accepted but only as read only files. You can put data in your geodatabase through several different tools: importing, loading data, loading objects or creating your own data. When uploading data make sure to take into consideration coordinate system, resolution, and data quality. After you upload the data, you can assign geometry types and styles for the data. The basic geometry types are point, multipoint, line, and polygon. 

After you upload you data, voila! You have a geodatabase that is now accessible for you to begin creating ArcMaps from the data you uploaded.

ROADBLOCK: Creating a feature class

Every time I ran through the steps to create a new feature class for 'Roads' ArcGIS gave me the following error, "Failure to create feature class because each grid size must be three times larger than the preceeding grid size." 

After looking into this, I found out that this error occurred because for the feature class I was creating was a raster model not a vector model. Raster models require a coordinate system in order to be uploaded which I had not yet assigned to my geodatabase. 

Lingering questions:

What is the difference between all of the file types available to upload into the geodatabase?

What is the difference between loading data and loading objects?

Key terms:

attribute: nonspatial information

feature class: geographic features with the same geometry type, same attributes, and same spatial reference

feature dataset: features within the feature class

footprint: what is this?

geodatabase: container that stores spatial and attribute data

mosaic dataset: collection of raster data sets (images) as one seamless image, it has three layers: boundary, footprint, and image

I suck at metadata, what's your trick?

Well I designed a large file geodatabase for an airport system plan in New Hampshire, for their DOT. The idea was to look at various services all these airports offered and look at ways to improve coverage. All states do this here and there. Anyway long story short I'm leaving the firm this week for a new job, so I am going through giving each layer some metadata. Pretty simple in ArcCatalog, just tons of layers. If you work at a firm I'd suggest noting the project name/number and the date created if known. Just quick "this is a point layer, I used it for X maps/analysis" in all the boxes they prompt you to fill out.

Major Duties/Responsibilities: The successful applicant will use geospatial tools and analyses to execute research and assessments on a wide range of environmental effects on aquatic resources of energy production. Key requirements of the position include acquiring, processing, and analyzing hydrologic geospatial data; designing, creating, and managing a relational database; preparation of maps, charts, and graphics; and preparation of technical reports and manuscripts. The position requires effective communication skills and the ability to work closely and successfully with other geospatial analysts, environmental scientists, engineers, economic analysts, hydrologists, and physical scientists. Especially desirable is someone who is self-directed and can take the initiative to provide technical support and training to team members on GIS concepts, techniques, and software. The successful candidate must go beyond using GIS tools to create maps, and have the ability to conduct more independent evaluation and more complex geospatial analyses.

Si tienes una geodatabase personal, y no tienes ArcGIS para abrirla, tranquilo, hay más opciones con QGIS. Para ello vamos a necesitar la librería gdal-filegdb... Para hacer esto descargamos y corremos como administrador este instalador de librerías oficial de OSGEO.