Georeferencing Flashcards
What is Georeferencing?
The act of assigning locations to atoms of information
- That is be unique, there is only one location associated with a given georeferenced, and therefore no confusion
- Shared among all of the people who wish to work with the information
- Must be persistent through time
These are the primary requirements of a ________
Georeference
Commonly Used Systems in Georeferencing
- Simplest form and is most likely the first one developed by early hunter-gatherer societies
- Any feature on the landscape can serve as point of reference
Place-Names and Points of Interest
Commonly Used Systems in Georeferencing
- Introduced after the development of mail delivery in the 19th century
- Provide unique identification for every dwelling and office on earth
Postal Addresses and Postal Codes
Commonly Used Systems in Georeferencing
- Provided whenever the computer is used to access a website, allowing the operators to determine the user’s location
- However, positional uncertainty will vary
IP Address
Commonly Used Systems in Georeferencing
Identifies location on a network by measuring distance from a defined point of reference along a defined path in the network
Linear Referencing Systems
Commonly Used Systems in Georeferencing
It is defined as the map of land ownership in an area, maintained for the purposes of taxing land or of creating a public record of ownership
Cadasters
Commonly Used Systems in Georeferencing
- Provides the potential for very accurate measurement of position, that allow distance to be computed between pairs of locations
- Most comprehensive and most powerful system of georeferencing
Latitude and Longitude
Commonly Used Systems in Georeferencing
- Much work in GIS deals with a flattened or projected earth, despite the price we pay in the distortions
- Transforms a position on the earth’s surface identified by latitude and longitude into a position in Cartesian coordinates
Projections
Definitions
The process of taking coded location information (such as addresses or grids) and turning it into explicit location information (X and Y coordinates)
Geocoding
Georeferencing is sometimes also called these two terms
georectification or georegistration
How to Georeference?
- When you take any ordinary image and give it ___________
- You can stretch, scale, rotate and skew the image to better relate to physical space
real-world coordinates
Definitions
The process of taking a raster image or vector coverage, assigning it a coordinate system and coordinates, and translating, transforming, and warping/rubbersheeting it into position relative to some other spatial data, such as survey locations, street intersections, etc.
Georeferencing
What are the 3 steps on how to georeference?
- Add Control Points for Matching Locations
- Select a Transformation or Rubbersheeting
- Check your Root Mean Square Error (RMSE)
