Midterm Flashcards
Cloud Computing
Data and software that in the past
has been stored on desktop computers
is now stored “in the cloud” thanks to wireless networking/higher speeds
Service-Oriented Architecture (SOA)
Service providers (server) and service consumers (clients) that communicate with each other
Geographic Approach
Step 1: Ask–“framing the question from a location-based
perspective”
– Step 2: Acquire–determine what data are needed
– Step 3: Examine—examine and evaluate the data
– Step 4: Analyze—process and analyze the data
– Step 5: Act—present the results
Georeferenced or registered layers
layers are all in the same
map projection, datum, and
coordinate-system
3 families of projections
1) Cylindrical
2) Conic
3) Planar/Azimuthal
Distortion ___ as the size of the geographic area that you
are working with _____.
increases, increases
Albers equal area/conical
equal area; conformal along standard parallels
uses: small regional and national maps
Azimuth equidistant/planar
equidistant: true directions from map center
uses: air and sea navigation charts; equatorial and polar area large-scale maps
Equidistant conic/conical
equidistant along standard parallel and central meridian
uses: region mapping of midlatitude areas with east-west extent; atlas maps for small countries
Lambert conformal conic/conical
conformal; true local directions
uses: navigation charts, U.S. State Plan Coordinate System for all east-west State Plane Zones; continental U.S. maps; Canadian maps
Mercator/cylindrical
conformal; true direction
uses: navigation charts, conformal world maps
polyconic/conical
equidistant along each standard parallel and central meridian
uses: topo maps; USGS 7.5 and 15 min quadrangles
4 Commonly Used Map Projections in GIS
Geographic or Plate Carree Projection
-Common native projection for exchanging data
– Albers Equal-Area Projection
-No area distortion, good for the United States
– Lambert Conformal Conic Projection
-No shape distortion, good for the United States. Used by some
states for SPCS
– Transverse Mercator
-Used for UTM coordinate system. Used by some states for SPCS
Projected coordinates are
simple x,y coordinates based
on some linear unit (e.g., meters)
Important Coordinate Systems for GIS:
Geographic Coordinate System • Latitude/Longitude – Cartesian Coordinate Systems • Universal Transverse Mercator (UTM) • State Plane Coordinate System (SPCS) • Other Projected Coordinates
Topology can be different for ___ feature classes in the ___ feature dataset.
different, same
Rule about feature classes in feature dataset
All features contained in must be in same projection and
coordinate system
5 Components to GIS data quality
Positional accuracy
– What is the position (X, Y) accuracy of features?
• Attribute accuracy
– Are the attribute values correct for features?
• Completeness
– Is the dataset complete? Does it cover the entire geographic
area of interest?
• Lineage = documentation about how a dataset was
derived, what steps were performed on the data
• Logical consistency = consistency of the data to other
datasets and the “real world”
Mean Center
Calculates the mean or average x and y coordinates (centroid)
for a set of features (points, lines, or polygons)
Weighted Mean Center
Features with higher attribute values will have a greater weight in the output weighted mean center
Central Feature
Identifies the most central feature from a set of points, lines, or
polygons
– Unlike the Mean Center, the Central Feature is at the coordinate
location for a feature that already exists
How is the standard distance calculated?
Steps: 1) Mean center is calculated first; 2) the average distance from the mean center is calculated for all points (standard distance/deviation); 3) Circle is drawn centered on the mean center using the standard distance/deviation as the radius
-more clustered = smaller circle and vice versa
Standard Deviation Ellipse
Like standard distance, measures concentration of features but also the directional trend
- standard deviation is calculated for the x and y coordinates separately, creating long and short axes (x standard distance and y standard distance)
If the null hypothesis is rejected, what happens?
There ARE statistically significant patterns.
