Mapping216

Geography
GIS
A computer assisted process designed to acquire, store, analyze and display spatial data and their attributes.
Attribute
Non spatial information about a geographic feature in a GIS, usually stored in a table and linked to the feature by a unique identifier. For example, attributes of a river might include its name, length, and sediment load at a gauging station.
Attribute Table
A database or tabular file containing information about a set of geographic features, usually arranged so that each row represents a feature and each column represents one feature attribute. In a GIS, attribute tables are often joined or related to spatial data layers, and the attribute values they contain can be used to find, query, and symbolize features or raster cells.
field
A column in a table that stores the values for a single attribute.
record
row, a whole line of attributes in a spreadsheet or attribute table
Forward query
getting information from an attribute table
Backward query
getting information from an attribute table
Point in polygon
selecting by relation to an arc or area (topology)
Buffering
a set distance in radius to a node or arc.
Polygon overlay
when you can select other polygons that are “touching” an arc. “Hallmark of GIS”
Basic Functions
Forward/backward query, point in polygon, buffering, polygon overlay
3 factors for analyzing GPS
Geo-referenced data, attributes, topology
geo-referenced data
Aligning geographic data to a known coordinate system so it can be viewed, queried, and analyzed with other geographic data.
topology
the spatial relationships between connecting arcs nodes polygons. It usually describes the starting node and all the other nodes until the end node in an arc or polygon in order to determine what is on the left or the right of the polygon.
2 ways computers store geographic data
vector, rastor
Vector
A coordinate-based data model that represents geographic features as points, lines, and polygons. Small file size.
Raster
the coordinate and color or every pixel is recorded. Is only accurate at the scale it was recorded. Large file size.
data classification types
Equal Interval, manual, quantile, Natural breaks
equal interval
divides a set of attribute values into equal sized subranges. ex. 3 groups of 20 attributes. Good for familiar data like temperature. Bad for revealing subtle differences
manual
Type in class limit values for the range settings and manually set class limits
Quantile
Features are ordered smallest to largest and then each class isassigned the same number of features. Bad in that two features may have nearly the same attribute value but fall into different categories.
Natural Breaks
Features ordered smallest to largest. Divided where there are relatively big jumps in the values. Bad bcuz class breaks seem random to viewer unless explained.
Normalizing data
Divide each value by sum total or values in another attribute, then map it
Normalizing by dividing by sum total
Derives percentage of total. Easier for viewer to compare relative size/importance.
Normalizing by dividing by values of another attribute
Allows you to account for influence/ control of another field. ex: Normalize birth/death rate by population. ex: Normalize population by area to map pop density
Accuracy
The degree to which a measured value conforms to true or accepted values. Accuracy is a measure of correctness.
Precision
The closeness of a repeated set of observations of the same quantity to one another. Precision is a measure of the control over random error. Exactness
Map
Spatial representation of the environment
Reference map
A map designed to show where geographic features are in relation to each other.
Thematic Map
A map designed to convey information about a single topic or theme, such as population density or geology.
Primary Mapping Sciences
Geodesy, Land Surveying and GPS, Remote Sensing
Geodesy
The science of meaning the size and shape of the Earth.
Land Surveying and GPS
The determination of the location of points and areas on Earth by measuring angle and distance.
Remote Sensing
Collecting and interpreting information about the environment and the surface of the earth from a distance. Ex. Satellite Images, aerial photos, collecting data without being there.
Secondary Mapping Sciences
GIS, Cartography
Geographic Information Systems
A computer assisted process designed to acquire, store, analyze and display spatial data and their attributes.
Map elements
neatline, border,graticule/ north arrow, scale, legend, title, sources and acknoweledgements
Building blocks
Tools to building a map include:Lettering, Basic Graphic Elements, Visual variables
Basic Graphic elements
point symbols, line symbols, areal symbols
Visual symbols
hue (subtle), value, chroma/saturation/intensity, size, shape, orientation
Objectives of cartographic design
simple is better and to stay away from unnecessary components or things that will clutter the map. the goal is convey a message spatially and convey area.
figure-ground” phenomenon
concept of how like a graduated symbol may look smaller or bigger compared to the space it is in
Map components of map design
Clarify and legibility, visual contrast, visual balance, figure-ground phenomenon, hierarchical organization
neatline
The border delineating and defining the extent of geographic data on a map

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