Ch 2: Data Flashcards
spatial
where an object is located or an event has occurred
temporal
when the location and attributes were accurate (when collected)
attribute
what characteristics the object or event has
example of spatial charactertistic
Spatial characteristics of data, like location of state boundaries(or address, coordinates) are needed to put the data on a map
example of temporal characteristic
Temporal characteristics refer to how data represent a “snapshot” of what things were like at the time the data were collected, such as census data from 2000
example of attribute characteristic
Attribute characteristics describe the nature of a location (population, income, etc)
2 main methods of spatial data collection
ground surveying and remote sensing
ground surveying
involves a person or mechanism that observes or interacts with people or the environ. in a particular place
remote sensing
refers to collecting data from afar, often by taking pics from a plane or satellite
ground surveying in depth
Ground surveying conducted through individual/mechanism interacting with a particular place
Can include a person collecting locational data with handset that works with GPS, constellation of satellites that beam signals to earth where they can be used to determine position
Surveys involve talking to people or traveling to different locations to gather info
Another kind of ground surveying occurs at weather stations that measure temp and other climatological info at a given location
what process is ground surveying similar to?
geo coding
what is geocoding
data with locational elements (address, zipcode) are matched to known ground coordinates
land surveying
-determines location
Use tools to determine precise positions of locations by triangulating from the position of known locations
Land surveyors helped map out many countries, working outward from known to unknown locations
gps in depth
GPS are constellations of satellites that orbit Earth
Satellites transmit signals to earth’s surface to indicate their position in space and a precise time signal
Device equipped with GPS receiver can interpret these signals and find device’s location earth
what type of surveying is gps considered
Considered ground surveying since it’s the handset or GPS unit that’s determining position from satellite signals
drawbacks of gps
signals can be blocked by solid objects and getting a strong signal can be hard, limited number of satellites orbiting Earth, depending on quality of handset GPS coordinates could be inaccurate
Space segment system based on velocity
control segment
ground stations that monitor and maintain the satellite vehicles
user segment
receivers detecting and interpreting signals (use signals to calculate position)
geo coding
process of attaching a geographic location to address information
Most use some form of database of addresses whose locations are precisely known
surveys
gather attribute info about individuals, households, businesses or area
Data gathered can be linked to location on a map
Census collects data on all members of a population
sensors
used to measure a wide array of human and environmental facts
Location determined by GPS, ground surveying or geocoding
remote sensing
-collected at a distance from object they are studying
Some sensors collect imagery with cameras
Detect different non visible parts of the electromagnetic spectrum, infrared (heat)
Used for monitoring changes in the environment over large areas (deforestation)
metadata
data about data that lets you assess how well the data can work with other data
example of metadata
Such as the content, source, lineage, methods, developer, coordinate systems, extent, structure, spatial accuracy and the responsible organization for spatial data