A map is a spatial pattern of one or more geographic attributes.

A map is used to provide specific information about particular locations, to provide general information about spatial patterns.

there are maps for different senses

ocular (sight)

tactile (feel)

olfactory (smell)

auditory

taste

"Everything is related to everything else, but near things are more related than distant things."

-Waldo Tobler

cartographers:

Eratosthenes calculated circumference of Earth based on measurements of shadows at two locations

Measured within 200 miles of actual circumference. He was one of the first geographers to partition the Earth. Parallels and meridians-longitude and latitude 

Ptolemy used geographia, coordinates, latitude & longitude, cartographic elements. Underestimated circumference of globe

John Snow made a map depicting the spread of Cholera

Through navigation (calculating distance, GPS, LBS)

Through measuring features on a map (length of line, area of polygon, using the "paper-strip" method)

combine geoid & reference ellipsoid either:

worldwide (average position anywhere on Earth's surface)

or

location specific (more precise location for a smaller geographic area)

Distortions of the surface include:

• area
• shape
• relative size
• direction

• Planar: tangent at a point, straight line direction representing great circles (azimuthal)
• Cylindrical: tangent at the equator, medians & parallels are straight & perpendicular, meridians are same distance apart
• Conic: tangent at parallel, medians are straight lines that converge at the poles)
•  Pseudo-cylindrical

• Polar/Normal- straight down from pole
• Equatorial/transverse- rotated 90 degrees from normal
• oblique- surface lies between normal and transverse

• Conformal: retains correct angular relationships on map, latitude and longitude cross at 90 degrees
• Equal-areas: preserves relative area not shape
• Equidistant: preserves scale & distance between one point & all other points on map
• Direction or Azimuthal: preserves direction between all points based on a central point

• size of area of interest (AOI)
• latitude of AOI
• shape of AOI
• areal distribution

Goal: Minimize extreme distortions

scale:small or large? available space?

purpose: what is the map's message?

audience: who will be using the map?

technical constraints:printing or display considerations, large data handling

reduces complexity

more accuracte

makes aesthetic quality

logical

consistent

ratio of map distance divided by the ground distance

RF = MD/GD

can be written as 1:24000 or 1/24000. 1 is always the numerator

What is a raster data model?

• constallation of 24 sattelites used for positioning, navigation, timing
• operated by US government
• receiver location based on location of minumum 4 satellites and signal

simplification (less points)

smoothing (reducing angles)

aggregation (grouping points to form one areal feature)

amalgamation (grouping smaller features into a larger one)

collapse (replacing physical feature with a symbol)

merging (grouping features)

refinement (selecting specific features that represent the entire feature)

exaggeration (amplifying portion of specific feature)

enhancement (highlighting message or aspect of a feature)

displacement (separating features)

• Organization
• Reduce redundancy
• Facilitate sharing data
• Efficient workflow

• collection
• purchase
• provided by client
• Downloaded from warehouse/clearing house (i.e Vermont Center for Geographic Information (VCGI), USGS, Commercial Vendors)

What is metadata?

List some properties of it

Data about the data with:

• a description
• a source
• coordinate system, datum, and scale
• accuracy
• contact and distribution info
• processing steps
• use restrictions

1. nominal: non-numeric data
2. ordianal:data that can be ranked but does not describe differences or measurements
3. interval: arbitrary zero value, allows multiplication
4. ratio: continuous measures such as weight, distance, time

1. equal interval: equally spaced intervals
2. quantile: equal number of values per interval
3. geometrical interval: consistent interval for continuous data
4. Jenks's Nautral Breaks: groups similar values, optimizes maximum differences

legend

scale

north arrow

figure

neat line

border

title

place name

inset

point: single coordinate pair

line: string of coordinate pairs

polygon: line where first pair and last pair are the same

• art and science
• detection of feature or phenomenon using a seonsor that is not in contact with feature or phenomenon

• spectral: range of values in the electromagnetic spectrum
• spatial: grid cell or pixel size; coarse, medium, or high
• radiometric: intensity
• temporal: how often the sensor returns to a given location

• red
• green
• blue
• infrared
• panchromatic

georectification: raster layer with no spatial reference,

orthorectification: base or reference imagery, with a terrain model

RADAR: Radio Detection and Ranging, backscatter records speed & direction, used in terrain models

LiDAR: Light Detection and Ranging, laser pulse provides elevation features at or above Earth's surface

topographical:

• Digital Elevation Model (DEM)
• Digital Terrain Model (DTM)

all of Earth's surface

• Digital Surface Model (DSM)
• Normalized Digital Surface Model (nDSM)