Chapter 2 Flashcards
Define ‘geodesy’
Per NOAA, “the science of measuring and monitoring the size and shape of the earth & the location of points on its surface”
Geodesy’ is “the science of ___ and ___ the ____ and ___ of the earth & the ___ of ____ on its ___”
“the science of measuring and monitoring the size and shape of the earth & the location of points on its surface”
Define & explain ‘classic geodesy’
area of science concerned with: – length of day – measuring size of earth – geometry of earth – creating non-digital location/nav methods
Define & explain ‘modern geodesy’
Helpful in studies of climate & environment + geohazards like quakes/tsunamis, the use of geodesy to monitor changes on earth such as: – surface deformation – crustal motion – polar motion – earth rotation – tides – the water cycle – sea levels – ocean circulation patterns – sea ice levels
What is accuracy in GIS?
Ability to hit a target
What is precision in GIS?
Ability to repeat results
What is error in GIS?
The linear distance between represented data & reality
Define & explain ‘GNSS’
General term for any system using locational satellites & triangulation to relearn the location of a receiver on the surface of earth. GPS is specifically the USA owner and operated version. It has 31 satellites. The more the better!
Define ‘topographic surface’
The ‘real world.’ The surface we walk on daily. The actual place where we want to find and label points.
How is the topographic surface defined?
Using landforms and relief.
What is relief in GIS?
Difference between highest and lowest point within a particular area.
What are landforms in GIS?
Descriptions of landscape features like mountains, valleys, & ridges.
Define and explain ‘geoid’
A model of the variation between global mean sea level (GMSL) & local mean sea level (LMSL), based on graviry, used to measure precise elevations on the topographic surface. ALSO: A model of sea level to establish elevation values. ALSO: a model of gravitational acceleration across the earth. ALSO: a way to set zero elevation.
Explain why geoids are used in GIS & cartography
To measure precise elevations on the topographic surface, via establishing a zero value for elevation of a feature
Define “ellipsoid”
An ellipse with a 3rd dimension added (to make a “fat ellipse”)