Chapter 2 Flashcards
Map Scale
relationship between distance measured + actual distance can never be fully accurate bc maps are flat + world is 3D
Graphic map scale
Scale/ruler at bottom which gives the actual distance represented
*line marked off in distances i.e. land nav maps**
ADVANTAGE = simplicity + remains accurate when map is enlarged + reduced (since the size of the ruler is also scaled)
DISADVANTAGE = Ruler given is small, so measuring longer distances is hard
Large scale map vs small scale map
Large scale = depicts small part of surface in a lot of detail (small denominator i.e. 1/10K)
Small scale = portrays large part of surface in less detail (only most important features) LARGE denominator i.e. 1/10mil
fractional map scale
gives relationship btwn map distance + real distance as ratio i.e. 1:250000
units on both sides of ratio r same
Verbal map scale
states the relationship in words i.e. one centimeter represents 10 kilometers (units do not need to be same like in fractional scale)
DISADVANTAGE = difficult for other cultures to understand (use diff. units of measurement)
map projection
process by which spherical surface of Earth is transformed onto flat surface
Equivalent map projection
Relative ratio of area on map to actual area on Earth’s surface maintained
PRO: useful in showing distribution of geographic features
CON: hard to achieve on small-scale maps –> end up w. distorted landmass shapes
Conformal map projection
FORM/SHAPE maintained
CON: Distorts sizes, i.e. Greenland looks way too big
Compromise projections
Mix between equivalent + conformal i.e. Robinson projection (general purpose classroom map)
What is GNSS
Global Navigation Satellite System,
combo of US, Russian, Chinese, European satellite systems
How does a GPS determine location
Trilateration = uses known distance between receiver & 4+ satellites to determine 3D coordinates
each satellite transmits ID + positioning info to receiver AKA you w. the GPS
GPS purposes
originally designed for military
Now:
- used by commercial, personal vehicles
- collects damage assessments post natural disasters
- earthquake forecasting, ocean floor mapping
- volcano monitoring, COVID 19 tracking
Remote sensing
Recording information from a device that is not in physical contact w. Earth’s surface
ex: satellites in low orbit around Earth, hovering over same location + gathering info (pictures, weather data, global positioning, etc)
Isoline
Line connecting points of equal value
- Show gradations in quantity (rainfall, elevation) + almost never intersect
- closed lines
EMS
special scanners used to detect things like IR
ir –> distinguish between living vegetation + dead vegetation used to cover enemy positions
Multispectral
remote sensing satellites detect many regions of EMS at the same time
info sent to a satellite then to a computer + creates specific pixels (color or in shades of gray) to produce image
Passive systems
Systems that work by sensing natural radiation emitted by or reflected from objects
ex: infrared, multispectral images,
Active system
has its OWN source of EMS i.e. RADAR, SONAR, LIDAR
Radar benefits
used to determine distance (bouncing off waves)
CAN BE USED IN WET AREAS
before it was impossible to use sensing tech for wet tropical areas UNTIL radar
Sonar
Underwater imaging for Earth’s crust
LIDAR
reflects laser light to measure distances –> provides much higher precision than remote sensing
What is a GIS
Geographic information system - analyzes + displays spatial data
overlay analysis
What is overlay analysis
2 or more layers of data are superimposed
GIS –> can combine multiple different maps showing diff things i.e. topography, land use, land ownership etc and make one map out of it with high precision
helps identify preferred locations when multiple variables are in play i.e. where to build a new housing development
