Geomapping Midterm Study Guide

geographic information systems

connect spatial data and list (attribute) data to answer geographical questions and solve geographical problems

spatial data

distance, intersection, adjacency, containment, plots the location of things on a grid

identify common uses of digital mapping and GIS

Visualization, spatial modeling, planning and infastructure, social science and policy, environmental research, information technology (dtaat management, software development, geo hardware) like social media and google maps

Identify how humans employ cognitive psychology to understand geography (and our cognitive biases)

we have the ability to think about geography abstractly (we can go around the grass to get the duck because we know the duck won’t be able to see us from where it is, where a dog would just lunge at it), we can recognize shapes as geographic things

explain how culture shapes how humans understand geography

some maps don’t use longitude or latitude, some cultures prioritize religion so their maps reflects that like the medieval europeans, how people understand geography veries across different places and time, examples of polynesian navigation

identify multiple definitions of “map” and common types of maps

map definitions: a graphic representation of the environment, a geographical proposition/argument, it looks like one in structure, elements (relies on coordinate systems/grid of longitude and latitude)

types of maps

reference maps, thematic maps, icon

reference maps

topography maps, google maps, about multiple things simultaneously

thematic maps

USA map, focuses on one topic

icon

texas sticker (even though word isn’t there you know it’s Texas) like the #1 glove, USA sticker

actual shape of the earth

irregular oblate ellipsoid

read latitude and longitude including DMS and DD

latitude: lateral line/parallel lines (like the equator) that measure the distance between north and south poles, longitudes: vertical lines (like prime meridian) and measure the distance between east and west, lines of latitude are further apart at the poles than near the equator

you can measure latitude and longitude location by

DMS: degrees, minutes, seconds, DD: decimal degrees (positive or negative numbers to differentiate between north, south, east, and west) north and east (+), south and west (-)

discrete geographic feature

objects on earth with distinct boundaries (an object based view) ex: states, cities, countries, bodies of water (often human-made)

continuous geographic feature

entities on earth with continuous spatial existence: without distinct boundaries, ex: no clear boundaries like elevation and natural features

vector geographic data

points, lines, and polygon defined by lat/long (xy coordinates) and an attribute table, best for discrete phenomena

raster geographic data

a grid of cells over a space, each with an attribute value (aka a bitmap), best for continuous phenomena

consequences and political effects of mapping and GIS

cartographic partition, marking people as “others”, helping produce modern governments and governing

gerrymandering

re-districting plans so they favor a particular party

cracking

spreading voters in the opposing party across multiple distrcits to deny them a larger voting bloc

packing

concentrating voters of an opposing party into a single district to reduce their influence elsewhere

consequences of gerrymandering

majority voters doesn’t mean majority seats in congress, politicians in a gerrymandered seat tend to be more extreme and less open to compromise

critical map reading

being aware of how a map (and its author) attempt to persuade you

map proposition

not the topic but what the author wants you to believe or accept

ways mapmakers try to persuade you

something appears on the map or doesn’t, visual hierarchy (what do you notice first), graphic elements

cartographic scale

mathematical relationship between a distance on the map and the corresponding distance on the surface of the earth

representative fraction

works for constant unit 1:24,000, (1 inch on the map is 1 inch on the ground) must be the same unit on both sides

generalization

the process of reducing the amount of information on a map through change to the geometric representation of the feature, more of the map but less detailed

measure distances with a map’s scale

ex: if 1:50,000 then three inches multiply both sides by three, 150,000 inches convert inches to miles (63360 inches in a mile), divide the distance by the number of inches per mile, 150,000/63360= 2.367 miles

determine the scale if it is not labeled

step 1- put everything in the same units, step 2- divide by measured units on the map

Global Positioning System

GPS needs at least 24 satellites for world wide coverage, the alternatives for other countries like GLONASS (Russian) and BeiDou (Chinese) so they don’t rely on the US, owned by the military

gps has three parts

space segment (the satellite), control segment (fix malfunctions, clock error), user segment (you with a gps receiver)

how gps works

broadcasts a signal stating its own current time and location, synchronized to send signals at the same time, receiver gets the signal and records the time delay between when the signal was sent by the satellite vs when the receiver got the message, indicating distance from satellite to receiver, receiver uses space trilateration to calculate its location based on the time delays from multiple satellites

space trilateration

a method for determining positions using the geometry of spheres in 3 dimensions, uses at least 4 satellites and the distance between the receiver and each satellite, calculates absolute position (a fix)

systematic gps error

gps signals are weak, number of visible satellites, relativity, dilution of precision (the arrangement of satellites in the sky), quartz crystal clocks are relatively accurate but fragile receivers

random gps error

multipath error (signal from the satellite bouncing off objects like buildings), range noise- radio signals at a similar frequency, atmospheric effects like storms or atmospheric refraction

ways to improve gps accuracy

point averaging, gps augmentation

gps augmentation

using external information to improve accuracy of gps readings (ex: differential gps using two gps receivers, wireless networks, cellphone towers)

web maps

google maps, google earth, waze, etc

location based services (LBS)

social media that use location like dating apps, food apps, weather

assembling data that has been made possible through LBS

crowdsourcing/user-generated content- photos and videos and personal location data, volunteered geographic information- voluntarily added by users (ex: open street maps, following a gps)

hacking maps that has been possible through LBS

housingmaps.com, zillow, restaurants, basically LBS now- games, social media, tours

different motivations of different players in this field

targeted advertising, consumption, geographic filter bubble so you can see what interests you and things in your area

forms of surveillance and limited standards of privacy at work in these technologies

government surveillance, private surveillance, privacy standards and its limitations

government surveillance

phone call metadate, internet traffic, location of mobile devices

private surveillance

personal location information like geographic habits, where friends and family are, groups you’re a member of

privacy standards and its limitations

4th amendment which forbids unreasonable searches and seizure of people’s property, but does not protect you from companies, can’t use tech that isn’t generally used, can’t force you to give your personal information, cultural expectations of privacy

augmented reality

a view of a physical, real-world environment with additional computer generated sensory input such as sound, video, graphics, or gps data

feature classes

single set of gis data, appear as layers in the contents and on the map

layers

how the gis data is presented

non-spatial data

nominal, ordinal, interval data, ratio data

nominal data

named types/categories/classes, ex: an individuals race or ethnicity

ordinal data

hierarchy of types, ex: olympic medalists

interval data

number and the zero are arbitrary (can’t go below zero) ex: elevation

ratio data

numbers can’t have less than zero, ex: money, number of married people in nassau county

raster data (in depth)

a grid of cells, each cell has a value and says something about that location, no gaps in the data takes up more space,

vector data (in depth)

no clear border, can be gaps, individual longitude and latitude for each one of them, can store all four categories of data

raster data storage

rs_data.gdb (storage database), (feature class), formats: .grid raster format native to ESRI, .tiff, .jpeg

vector feature classes

multiple files or databases, demo_pro.gdb (storage geodatabase), polygon feature class (dice-like thing), point feature class (dot things), line feature class, table (no spatial data)

how many inches in a mile

63000

1 foot in inches

12 inches

1 meter in centimeters

100 centimeters

1 kilometer in meters

1000 meters

1 kilometer in centimeters

100,000 centimeters

1 mile in feet

5280 feet

receivers only receive data from

a satellite, never send it and every satellite knows where it is, how fast its moving, and what time it is

longitude is vertical lines, measure

how east or west you are