Midterm Review Flashcards
What is GIS?
GIS is an information system used to manipulate, summarize, query, edit, and visualize spatial and non-spatial information stored in a computer database.
The GIS Process: six processes:
1) Physical world, 2) define GIS Protocol 3) Collect spatial and non spatial data, 4) Data analysis and edit, 5) Report the results, and 6) Take action and make policy
GIS applications in many fields:
1) typhoon/ hurricane monitoring, map the hyphone track and know where the most affected
areas are.
2) population migration, map the population flow from the origin country to the destination
country.
3) fire evacuation, map the fire evacuation routes in the fire incidence
4) disaster management……
5) endangered species protection
Farther of GIS:
Roger Tomlinson
Founder of GIS Harvard Laboratory:
Howard Fisher
Founder of ESRI:
Jack and Laura Dangermond.
Is a paper map a GIS? Why or why not?
Paper map: a static map. Cannot zoom in and zoom out. Cannot do a spatial analysis. It is not a computer-
based system. Can be used as a base for GIS though.
Which GIS software do you use in our lab class? How does this GIS software different from most other software.
We use ArcGIS Pro 2.9 for the class. We do not use ArcGIS Desktop
Vector data:
Points, lines, and Polygons, include topology.
Advantages: 1) compact data structure, 2) topology, perform the network analysis 3) used in discrete features, points, polylines, polygons, preserve the spatial accuracy of these discrete features.
Disadvantages: 1) it is a complex data source; 2) for the topology, we have to consider the connectivity between the neighboring polygons; 3) is not efficient to represent the continuous feature (elevation)
File formats for vectors:
Coverage (retired), Shapefile, ArcGIS Geodatabse (.gdb), enterprise Geodatabase (.ArcSDE) KML/KMZ are google maps and google Earth. XY units are used for map data.
Which is most commonly used geodatabse in ArcGIS and our class?
File Geodatebase (.gdb)
Shapefiles (what are mandatory files?), multiple files with same name but different extensions
1) .shp (geometry information); 2) .dbf (attribute information); 3) .shx (index information).
Raster data
(cells = grids, cell size= spatial resolution, JPEG, TIFF, PNG files are all raster data) (Also smaller cell size means higher spatial resolution) No topology
Vector data (pros and cons) and raster data (pros and cons)
Vector format also allows for complex spatial analysis and operations, as well as requiring less storage space than raster format for the same level of detail. However, it can be difficult to represent continuous phenomena, such as elevation or temperature, and is prone to topological errors like gaps and overlaps. (Reverse these for Raster)
Conversion between vector and raster data:
do not convert many times (maximum 2 times)
Data Type (Most numbers are ratio, interval is basically just temp and elevation)
(1) Temperature: it does not have the meaning zero, interval data
(2) Elevation: it does not have the meaningful zero, interval data
(3) Population: it does have the meaningful zero; ratio data
(4) Building Name: nominal data
(5) City size: small, medium, and large; ordinal
(6) Hurricane type: tornado, typhoon, hurricane, categorical data
Qualitative thematic maps: does not tell the magnitude of the variables.
Which are used for Nominal/Ordinal/categorical?
(1) Nominal, use the single symbol map and turn on the labeling of the field
(2) Categorical, use the unique values map
(3) Ordinal, use the unique values map
Graduate color maps or choropleth maps:
relative data (proportion, percentage, ratio)
Bivariate color maps or bivariate choropleth maps:
display two variables on one map (relative data)
Graduated symbol maps:
absolute data; both positive and negative absolute data, classified for the data
Proportional symbol maps:
absolute data: positive absolute data, unclassified or classified data works
Pie chart:
multiple variables (of the same categories): absolute data and relative data
Dot density maps:
show population data : absolute data
Cartogram maps:
not available in ArcGIS Pro. Prioritize the specific theme over the spatial accuracy.
What are required elements in a map layout?
1) Title 2) scale bar 3) legend 4) north arrow
What are optional elements in a map layout?
1) Author name 2) date 3) data source 4) explanatory text 5) coordinate system
What should a title have?
do not use the abbreviations, include geographic regions and unit, do not use Map in the title, always be largest on the map
Scale:
use easy number to represent scale on the map. 1: 300 vs. 1:317
Also remember population is absolute, use graduated symbol map
When to use North Arrow vs. Graticule?
North arrow is used in 2 D mapping and analysis (CS is in PCS)
Graticule is sued in 3 D globe (CS is in GCS)
The best approximation of the earth is:
Ellipsoid