Exam 1 Flashcards
Define GIS
Stands for geographic information system. It is an interface and computer system for representing and analyzing spatial data
Define UTM
Universal Transverse Mercator. A cylindrical projection with poles parallel to the cylinder. Most of the distortion happens at the poles
Define meridian
A line of longitude. Running from pole to pole
Define remote sensing + devices
Remote sensing is collecting data on an object or phenomenon without being in physical connection with it
Devices:
- drones
- LANDSAT imagery
- LIDAR
- NDVI - normalized difference vegetation index
Define resolution
the level of detail which a map depicts spatial, spectral, temporal, or radiometric parameters
Define spheroid
A sphere flattened at the poles
Define geodesy
the science of mapping the earth
Define geoid surface
A 3D representation of the earth’s surface that has an irregular spheroidal shape in order to take into account the variation in the earth’s gravitational field
Define scale
the spatial and temporal dimensions of an object or process
Define topology
A collection of rules and relationships that enables spatial data to more accurately model geometric relationships found in the real world. Examples: inclusion, adjacency, connectivity
Compare and contrast: Vector vs Raster
Raster data is represented in a grid, with each pixel or square being assigned a specific value. Raster is faster and vaster. Map outputs blocky
Vector data consists of points, lines and polygons. Raster is vaster, but vector is corrector. Has a more complex data structure
Compare and contrast: Projection systems (Mercator, unprojected, Lambert’s conformal, Transverse Mercator, etc.)
Mercator - cylindrical projection with poles parallel to cylinder wall. great distortion near poles.
Unprojected - Only based on lat and long, no projecting Good for navigation or worldwide coverage. Areas stretched at poles and shrunk at equator
Lambert’s conformal - Angles are correct. Conserves angles and shapes, but not their size. Good for navigation by compass
Transverse Mercator - Cylindrical projection with poles perpindicular to cylinder. Most distortion happens near the equator
Planar projection - a plane touches the globe at a single point. Good for small areas of interes
Equidistant cylindrical projection - all distances are to scale, lines of long are equally spaced
Conformal - angles for navigation are correct, conserves both angles and shapes, but not size
Compare and contrast: precision vs. accuracy
Precision - the nearness of a measurement to the standard or true value
Precision - the degree to which measurements are close to each other
small scale vs. large scale map
A large scale map (1:24,000) is more detailed, and will show more detail in a smaller area
A small scale map (1:250,000) will be less detailed and show a larger area
Landsat vs. NAIP
Landsat data has 8 bands and the pixel size is 30x30m
NAIP imagery has 3 bands and pixel size is 0.6x0.6m
You would want to use Landsat if you want to look at the amount and vigor of vegetation over a large area (because it has more bands including near infra-red). You would also use Landsat to look at changes in a landscape over time at a temporal scale of weeks, months or one year.
You would want to use NAIP if you want a finer pixel resolution, for creating finer-scaled maps where looking at infrared light, or analyzing the spectral quality of pixels is not important. You would use NAIP if you wanted a temporal scale of 2 years or greater.
