Getting Started with Data Management Flashcards
Identify key characteristics of GIS data and identify ways that GIS data is stored and accessed.
What is vector data?
Points, lines, and polygons. They’re composed of geometry and attributes.
What is raster data?
A grid of cells. Each cell contains a value for a particular phenomenon. Raster data typically depicts continous data and doesn’t have attributes.
What are derived rasters?
They add context and value such as hillshade. It often involves applying mathematical or statistical operations to the source raster data. They don’t have attributes.
As an example, you could use a DEM as a source data for elevation. Then you can apply statistics to see the sinks in the DEM that might trap water to help create watershed boundaries.
How does imagery or scanned maps relate to rasters?
They are a discrete form of rasters. Think of the basemaps and the image layers. They are represented by a grid of pixels. Imagery captures real-world scenes from satellites or aerial sensors, while scanned maps digitize existing paper maps.
What are coordinate systems?
A grid of communication geographic location. Location using coordinate systems can be described with x, y coordinates of latitude and longitude, state plane in feet and direction, and UTM in meters and direction.
What is metadata?
Data about the data. Can include author, date the data was created or modified, and descriptive tags.
What are the 4 ways you can maintain data integrity?
Domains, Subtypes, Topology, and Archiving
What are domains?
A list of options to choose from
Subtypes
A subset of features that share the same attribute
Topology
(A data integrity method)
Defines the spatial relationship you want to protect in your data.
Think of it as a lock.
Archiving
Allows temporal analytical capabilities by documenting change over time. Can help answer how have the features and attributes changed over time?
What is a SHP?
The main shapefile. It stores feature geometry.
What is a SHX?
A file that stores the index of feature geometry.
What is a DBF?
A file that stores attribute information.
What is a PRJ?
A file that stores the coordinate system information.
