Shared Flashcard Set

Details

Advanced GIS
Dr, Filippi's Advanced GIS Test
363
Geography
Undergraduate 4
02/18/2013

Additional Geography Flashcards

 


 

Cards

Term
Data
Definition
a collection of facts or figures that pertain to places, people, things, events, concepts
Term
Information
Definition
processed or value added data that have certain perceived values to a user or a community of users
Term
Knowledge
Definition
transformation of data into information is an explicit act by a user to raise their ___ to a level appropriate for specific decision making purposes
Term
Intelligence
Definition
When a user deploys knowledge to perceive relationships, formulate principles, and introduce personal values
Term
System
Definition

1. formed or constructed to achieve certain basic objectives or functions

2. their continuing existence depends on their ability to satisfy the intended objectives-if this ability fails or starts to decline, systems concerned must be upgraded or replaced

3. individual system is composed of many interrelated parts which may be operational systems by themselves

4. these parts operate individually and interact with one another according to certain rules of conduct such as procedures, laws, contractual agreements, and accepted behavior

Term
Information Systems
Definition

1. is set up to achieve the specific objectives of collecting, storing, analyzing, and presenting information in a systematic manner.

2. structurally is made up of interrelated components that include a combination of data and technical and human resources

3. being made up of input, processing, and output systems, all working according to a well-defined set of operational procedures and protocols.

4. can be operated independently and at the same time linked with other information systems

Term
Information System Network
Definition
  • The data and technical and human resources used to form the system
  • communications protocol and data management procedure
  • functional subsystems
  • stand-alone or network mode of systems or network mode of systems configurations
Term
Nonspatial Information systems
Definition
those designed for processing data that are not referenced to any position in geographic space. For example, a system for accounting.
Term
Spatial Information Systems
Definition
those designed for processing data pertaining to real-world features or phenomena that are described in terms of locations
Term

True/False

 

 

All Spatial information systems can be regarded as GIS

Definition

False

 

CAD systems, CAM systems are also spatial information systems

Term

True/False

 

 

 

Only those spatial information systems that are ussed for processing and analyzing geospatial data or geographically referenced data can be labeled as a GIS

Definition
True
Term
Geospatial Data
Definition
  • Characterized by geographic space
  • Representation at geographic scale
Term
Geographic Space
Definition
data are registered to an accepted geographic coordinate system of Earth's system so that data from different sources can be spatially cross referenced
Term
Geographic Scale
Definition
data are normally recorded at relatively small scales and must be generalized and symbolized
Term

Land Information Systems (LIS)

 

Land Related Information Systems (LRIS)

Definition
focus of the system on land related activities such as ownership, tax assessment, land and water resources
Term
Geographic Information Science
Definition

set of basic research issues raised by the handling of geographic information that include geographic data, problem solving, and using geographic information on society

 

Aims to provide the theoretical and organizational coherence for the scientific study of geographic information

Term

True/False

 

 

Canada produced the first ever GIS

Definition
True
Term

True/False

 

 

 

GIS was application driven during the 1960's-70's- built to meet specific information needs of individual organizations

Definition
True
Term
Topology
Definition
refers to the spatial relationship of adjacenc, connectivity, and containment among topographic features
Term
Impacts of Topology
Definition
  • solved data representation problem that hindered GIS in the early years
  • reduced the complexity of applying geographic data for spatial analysis, thus making GIS easier to use
  • geospatial data can be stored in a simple structure that is capable of respresenting their attributes
Term
ESRI
Definition
  • created ArcInfo released in 1982
  • vector based GIS to use georelational data model that employed hybrid approach to geographic data processing
  • graphical data stored using topological data structure, while attribute data are stored using relational or tabular data structure
Term
GIS 1980s-1990s
Definition
  • shifted to data oriented approach of GIS development fundamentally changed the way GIS technology had been developed
  • designed to meet demand of corporate business goals
Term
enterprise Computing environment
Definition
integration of geographic data with other type of business data
Term
Information infrastructure
Definition
  • emerged in early 1990s when U.S. proposed Nation information Initiative
  • intended to provide access to information affecting their lives that pertains to governement, health care, education, and community development
Term
Location Based Service (LBS)
Definition
LBS makes use of the information about the location of the mobile computer to deliver personalized, localized, and real time geographic services to the user.
Term

Safety Services

 

Definition
enhanced 911 capable of identifying the location of the user in case of emergency
Term
information services
Definition
traffic information, navigation assistance, yellow pages, and travel/tourism information
Term
Enterprise services
Definition
vehicle tracking, logistic planning, utility asset inspection and management
Term
consumer portal services
Definition
delivery of local news, weather report, and forecast, driving directions
Term
Telematics services
Definition
using GPS technology to obtain real time location information to provide driving directions and vehicle tracking functionality in fleet management
Term
triggered location services
Definition
including location senstive advertising, billing, and logistics
Term
Location Awareness
Definition
obtaining location based information by means of coordinates
Term
Components of GIS
Definition
  • data
  • technology
  • application
  • people
Term
Geospatial Data
Definition

can be categorized into

  • geodetic control network
  • topographic base
  • graphical overlays
Term
Geodetic Control Network
Definition
  • foundation of all geographic data
  • provides goegraphical framework by which different sets of geospatial data can be spatially cross-referenced with another
  • established by high-precision surveying methods and vigorous computation at the national or contintal level.
Term
Topographic Base
Definition

created as the result of a basic mapping program by national state/ provincial, and local government mapping agencies

 

land surveying and phtogrammetry

Term
Graphical Overlays
Definition
  • thematic data pertaining to specific GIS applications
  • overlays of physical features can be derived directly from the topographic base
  • can be collected by site investigation
Term
Vector
Definition
data that depict the real world by means of discrete points, lines, and polygons
Term
Raster
Definition

Data depict the real world by means of a grid of cells with spectral or attribute values

 

not good for representing individually identifiable features but is ideal for a variety of spatial analysis functions

Term
Surface Data
Definition
depict the real world by means of a set of selected points or continuous lines of equal vales and can be analyzed and displayed in two or three dimensions and are most suited for natural phenomena
Term
GIS Database
Definition
can be formed by aggregating one or more geodatabases, usually organized into broad categories such as land use, transportation, hydrology, environment, and utility
Term
Hardware
Definition
made up of a configuration of core and peripheral equipment that is used for the acquisition, storage, analysis, and display of geographic information.
Term
Central Processing Unit (CPU)
Definition
perfoms all the data processing and analysis tasks and controls the input/output connectivity with data aquisition, storage, and display systems
Term
Conventionally GIS
Definition
were developed as tand alone applications that ran on a single host computer, but todays GIS are mostly implemented in a network environment using the client/server model.
Term
Server
Definition
the computer on which the data and software aer stored
Term
Client
Definition
computer by which users access the server
Term
Software
Definition
GIS conventionaly developed using a hybrid approach that handled graphical and descriptive components of geospatial data separately
Term
geographical data engine
Definition
a proprietary of GIS software that handled graphical data
Term
Georelational datamodel
Definition
connection between the graphical data engine and the database management system (DBMS)
Term
data mining
Definition
allow users to identify facts about the real world and transform these facts into geographic objects useful for geospatial data processing and analysis
Term
The use of object oriented technologies
Definition
has transformed GIS from automated filing cabinets of maps into smart machines for geographic knowledge
Term
toolbox approach
Definition
allows for users to customize their applications by using scripting language to build software extensions
Term
component software
Definition
software engineering methodolgy that has been evolving since the early 1990s, addresses the integration of separate computer based applications such as document imaging, optical character recognition, database query.
Term
GIS as a field of academic study
Definition
  • Cartography
  • remote sensing
  • mathematics
  • statistics
  • computer science
  • information technology
  • geography
  • urban planning 
  • resource management
Term
GIS as a branch of information technology
Definition
  • cartography
  • remote sensing
  • computer programming
  • software-specific training
  • workshops
  • laboratories
Term
GIS as a data institution
Definition
  • information technology
  • law
  • sociology
  • antrhopology
  • cognitive science
  • economics
  • political science
  • public administration
Term
Geographic Scale
Definition
Scales of interest to human activity/interaction. Refers to spaces concerning the Earth's surface or near-surface
Term
Spatial Scale
Definition
Can refer to a theoretical or mathematical space and can thus be applied to all spaces and scales, real and otherwise
Term

 

Geographic Space

Definition
The commonality of both the data and the problems that the systems are developed solve is geography, i.e. location, distribution, pattern and relationship within a specific geographical reference framework
Term

 

Geographic Scale

 

Definition
data usually recorded at relatively small scales and must thus be generalized and symbolized
Term
Define GIS
Definition
GIS is a collection of hardware, software, data, policies, procedures, and people for the input, storage and retrieval, manipulation and analysis, output and modeling of spatially referenced data
Term
Pacel Based LIS
Definition
emphasis on landownership and other castral applications. lands divided into parcels that have legal descriptions
Term
non-parcel bassed LIS
Definition
natural resources IS, used for habitat/wildlife evaluation and management, flood hazard mitigation, conservation easement, etc.
Term
What is not a GIS?
Definition
  • CAD, CAM, CAC
  • automated mapping
  • Database Management Systems (DBMS)
Term

Types of GIS Software Packages

 

Definition
  • Grass
  • ArcInfo
  • ArcMap
  • IDRISI
Term
Computing planar distance using distance theorem
Definition

d-√(x2-x1)^2 + (y2-y1)^2

 

 

where X2-x1 = difference in longitude

 

where y2-y1 = difference in latitude

 

D = distance between two points

Term
Communication Paradigm
Definition
assumed that map itself was a final product designed to communicate a spatial pattern via symbols, class limit determinations etc.
Term

Analytical paradigm

 

Definition
maintains raaw data in computer storage device for subsequent analysis - GIS
Term
Map
Definition
generalized view of an area as seen from above typically reduced in size
Term
cartography
Definition
subfield of geography that focuses on map-making
Term
scale
Definition
ratio of map units to ground units
Term
projection
Definition
process of transforming spherical Earth to flat map
Term
Map Projections
Definition
can be perspective or nonperspective
Term
Perspective Map projection
Definition
strictly geometric, use of a point of origin, or viewpoint, and a surface of projection. viewpoint selected baased on a certain critieria
Term
Nonperspective Map Projection
Definition
modifying the perspective projection to maintain desired properties - Ex. Mercator Map
Term
Map projections
Definition
can be expressed according to generalized functional relationships between geographical coordinates of a point on the Earth's surface and the coordinates on the plane
Term
Properties of Globes
Definition
parallels are always parallel to each other, meridian converge at poles and are evenly spaced along any parallel; distance between parallels decreases towards poles
Term
Map projection properties
Definition
  • area
  • shape
  • distance
  • direction
Term
Shape
Definition
  • to maintain shape make the scale along the meridian and paralell the same in both directions
  • preserving shaped distorts the distances
Term
Meridians
Definition
intersect parallels at right angles
Term
Area
Definition
  • shows spatial distributions and relative sizes of spatial features
  • tradeoffs of preserving area are the shape distance and occasionally directions are distorted
Term
true direction
Definition
inherent property of azimuthal class projections since all meridians pass through the pole
Term
Conformal Projection
Definition
naturally preserves shapes and true direction
Term
Mercator Projection
Definition
  • Gerardus Mercator 
  • Cylindrical projection
  • true shape
  • meridians equally spaced
  • rhumb lines enable plotting direction (good for navigation)
Term
Disadvantages of Mercator Projection
Definition

midlatitude and poleword landmasses dramatically stretched 

 

Term
Classes of Projection
Definition
  • Cylindrical
  • conical
  • planar
Term
Cylindrical Projection
Definition
  • cylinder assumed to circumscribe a transparent globe such that a cylinder touches the equator throughout its circumference
  • meridians are vertical and parallel lines
  • parallels are horizontal straight lines
Term
Conical Projections
Definition
  • come placed over globe such that the apex of the cone is exactly over the polar axis
  • cone must touch globe along a parallel of latitude
  • along standard parallel, scale is correct
  • parallels are arcs of circles
Term
Planar or Azimuthal Projections
Definition
  • Plane Touches the globe at North or South Pole
  • Like a cone flattened until vertex reaches a limit of 180 degrees
  • shape is circular
  • meridians look like straight lines eminating from the circle
  • parallels are complete circles centered at the pole
Term
Universal Transverse Mercator (UTM)
Definition
  • used to define horizontal positions world wide 6 degree zones each mapped by transverse Mercator Projection
Term
Fuller Transformation
Definition
  • preserves land masses
  • very little distortion in both shape and area
  • no more than 2% error
Term
Defining Projections in Arc/Info
Definition
for coverages, tins and grids projection information is stored as a PRJ file within their subdirectory and store as a file name .prj
Term
Cover
Definition

projection information is written to the PRJ of a coverage

 

Term
Grid
Definition
projection information is written to the PRJ of a grid
Term
File
Definition
projection information is written to the PRJ of an ASCII text file
Term
TIN
Definition
projection information is written to the PRJ of a tin
Term
<target>
Definition
data set for which the projection information is being defined
Term
Georeferencing
Definition
the representation of the location of real world features within the spatial framework of a particular coordinate system
Term
objective
Definition
provide a rigid spatial framework by which the positions of real-world features are measured, computed, recorded, and analyzed
Term
geoid and ellipsoid
Definition
deal iwth representing the physical shape of the Earth via a mathematical surface
Term
Ellipsoid
Definition
  • the reference surface for horizontal positions
  • physical shape of the real earth is closely approximated by the rotational ellipsoid
  • reference surface for horizontal coordinates (lat/long)
Term
f = (a-b)/ a
Definition

Amount of polar flattening 

 

where a and be are lengths of major and minor semi axes of the ellipse

Term
Eccentricity
Definition
e2= (a2-b2)/ a2
Term
Geoid
Definition
  • means earthlike
  • shape of the earth if oceans were allowed to flow freely under the continents
  • geoid rises over the continents and is depressed over the oceans
  • coincides with mean seal level
  • reference surface for vertical coordinates
Term
equipotential surface
Definition
surface on which the gravity potential is constant everywhere
Term
Datum
Definition
model that describes the position, direction, and scale of relationships of a reference surface to positions on the surface of Earth
Term
Geodetic datums
Definition
  • established to provide positional control that supports surveying and mapping projects covering large geographic areas
  • provide positional control that supports surveying and mapping projects covering large geographic areas
Term
vertical datum
Definition
  • zero surface from which all elevations or heights are measured
  • MSL was used as a vertical datum since MSL is available worldwide
Term
Geocentric Datum
Definition
  • referenced by 3-D cartesian coordinate systems (x,y,z) with the origin coincident with the center of the ellipsoid
Term
Relation b/w Coordinate Systems and Map Projections
Definition
  • coordinate systems formed on the basis on map projections but they are not map projections themselves
  • coordinate systems and map projections are different concepts with different purposes
  • map projections define how poisitons on Earth's surface are transformed onto a flat map surface
  • the coordinate system is then superimposed on the surface to provide a referencing framework by which positions are measured and computed
Term
Universal Transverse Mercator
Definition
projection is used to define the horizontal positions into 6 degree zones, each mapped by the Transverse Mercator projection with a central meridian in the center of the zone
Term
Spatial Relationships
Definition
  • Topological Relationships
  • continguity- next to sharing a border
  • connectivity - connected to, allowing flow from one to the other
  • proximity- near
  • closure contained
Term
Spatial attributes
Definition
always interested in location
Term

Non-Spatial Attributes

 

Definition

easily handled by non-spatial databases

 

 

spatial attributes and relationships are not handled well by non-spatial databases

Term
Spatial Data Aquisition
Definition

Land Surveying

Remote Sensing

Global Positioning System

Term
Geographic Data Collection
Definition
  • ground surveys
  • tape measures
  • LIDAR
Term
Global Position Systems (GPS)
Definition
  • U.S. DoD project devised in 1970s
  • constellation of 24 satellites
  • 6 orbital planes
  • 55 degree inclination
  • receiver computes position, velocity, time, four GPS satellites used to calculate position in 3 dimensions to offset receiver clock errors
Term
Radio Frequency Identification (RFID)
Definition
  • Can be passive or active
  • can range from few cms to 20-30 ft
  • high powered tags can tansmit into low orbit
  • Point of sale terminals used for customer tacking
Term
RFID
Definition
  • Can be virtually undetectable
  • can be woven into materials
  • uses a 96-bit code as a string of 96 zeroes and ones
Term
Examples of GIS
Definition
  • Digital Raster Graphic (DRG)
  • Digital Line Graph (DLG)
  • Digital Elevation Model (DEM)
  • LiDAR derived elevation data
Term
Non spatial Data for Thematic Mapping
Definition
  • Geographic referencing for attribute data uses the hierarchical referencing system
  • discrete often parcelled based
  • municipal addresses
Term
Non Spatial Levels of Measurement
Definition

usually determined by the valid operations

  • numerical levels
Term
Steven's Levels of Measurement
Definition
  • Binary Scale
  • Nominal Scale
  • Ordinal Scale
  • Interval Scale
  • Ratio Scale
Term
Binary Scale
Definition
presence or absence. frequently used to represent discrete data in raster systems
Term
Nominal Scale
Definition
making distinctions in kind/class category
Term
Ordinal Scale
Definition
  • Difference in Rank
  • can go beyond just equal or not equal
  • sorting is possible
  • non parametric/ qualitative
Term

Interval Scale

 

Definition
uses a relative scale, zero is arbitrary and can have negative values
Term
Ratio Scale
Definition
uses an abosolute zero. zero represents the absence of phenomena
Term
Criticism of Steven's levels of measurement
Definition
  • not adequate to address all possible circumstances in cartography and GIS
  • ratio is not the highest level of measurement
  • cyclic measures do not fit the concept of scale well
Term
Data Dictionary
Definition
defines our terms, levels of measurement, translates computer representation or attributes.
Term
Data entry
Definition
  • Manual coordinate capture
  • attribute capture
  • digital coordinate capture
  • data import
Term
Editing
Definition
  • manual point, line, and area feature of editing
  • manual attribute editing
  • automated error detection and editing
Term
data management
Definition
  • copy, subset, merge data
  • versioning
  • data registration and projectiong
  • summarization, data reduction
  • documentation
Term
Analysis
Definition
  • spatial query
  • attribute query
  • interpolation
  • connectivity
  • proximity and adjacency
  • buffering
  • terrain analysis
  • boundary dissolve
  • spatial data overlay
  • moving window analysis
  • map algebra
Term
Output
Definition
  • map design and layout
  • hardcopy map printing
  • digital graphic production
  • export format generation
  • metadata output
  • digital map serving
Term
Cartography
Definition
  • historically cartographic products from GIS not Good
  • Digital Maps (soft copy)
Term
human computer interaction
Definition
optimization of communication and presentation of geographic information
Term
Computational Steering
Definition
user views intermediate results of spatial analysis and based on those results, the algorithmic parameters may be interactively changed
Term
Isarithmic Mapping
Definition
  • mapping a real or conceptual 3-D geographical volume with quantitative line symbols. It is a planimetric representation of a 3-D volume
Term
Two forms of Isarithmic Maps
Definition
  • Isometric
  • Isoplethic

 

Both involve the planimetric mapping of the traces of the intersections of horizontal planes with the 3-D surface

Term
Isometric Maps
Definition

generated from point data

 

Actual - measure with instruments or other point sampling techniques

 

Derived- statistiacal measures and magnitudes

Term
Isoplethic Maps
Definition
generated from mapping data that occured over geographic areas called unit series
Term
Isarithmic Map Construction
Definition
  • magnitude or value of this isarithmic lines represent their vertical distance from teh data
  • planes constructed parallel to the Datum - each isarithm will have a constance magnitude, distance from the datum
Term
When to use Isarithmic Maps
Definition
  • mapped data must be a geographical volume and must have a surface that bounds the volume
  • data must be continuous, not discrete
  • must be familiar with the phenomenon being mapped
Term
Nearest Neighbor Interpoloation (Thiessen Polygons)
Definition
  • Assumption is that the value at each given location is the same as teh value of the nearest observation
  • Uses the concept of Thiessen Polygons
  • defined around each observation 
  • only one observation is contained in each polygon
Term
Advantages of Nearest Neighbour Interpolation
Definition
most appropriate for qualitative data (nominal in scale)
Term
Disadvantages
Definition
  • assumes values only change at the borders
  • does not perform well with interval or ratio scale data because it is a continuous surface
  • resulting surface is discontinuous without smooth graduations between observed values
Term
Inverse Distance Weighted Interpolation
Definition
  • Assumption:
  • the value of an attribute z for each unvisited grid cell location is DISTANCE WEIGHTED AVERAGE of data points located at nearby observations
  • Original data points are located on a regular grid or irregularly distributed and interpolated to locations on a denser regular grid
Term
Inverse Distance Weighted Method
Definition

d= distance between given and observed

z- observation point

N = number of observations

i = iteration

z1 = weighted value at a given point

T - weighting parameter

Term
What is the Relationship between r and nearby points in the Inverse Distance Weighted Method
Definition
An increase in r means that the distance is more heavily weighted; thus, the predicted value will be more like closer values
Term

Inverse Distance Weighted IDW Interpolation summary

 

Definition
  • based on the principle in geography that things closer together are more similar
  • if considering a location with no measured valuek IDW will look within a specified neighborhood around the point of interest and identity of the measured value
  • the closer observations will influence the predicted value more than observations measured farther away
  • closer points are thus more heavily weighted than points further away.. IDW as the distance from the point-to be predicted increase the values become more inversely wieghted
Term
Inverse Distance Weighted Interpolation
Definition

Advantages

  • results in a smooth and continuous surface that changes between observations
  • derived surface passes through observed values

Disadvantages

  • requires subjective selection of parameters 
  • does not interpolate beyond min and max values in observation sets
Term
Design Process
Definition
  • Graphic design produces visual forms
  • assign qualitative and quantitative meaning s to the distinctive marks - relate graphic characteristics of the marks to attributes of the data
  • arrange the marks in a total composition that enhances map communication with teh user, wehre the intended information is conveyed
  • skill and artistry important for map design
Term
Criteria for a Good Decision
Definition
  • should be suited to the needs of map users
  • should be easy to use
  • should be accurate, present information without error and distortion
  • should be clear, legible, and aesthetically pleasing
  • symbols, color, layout, and typographic appearence
  • should be thought provoking and communicative
Term

Design of Symbols

 

Definition
  • Class of symbols
  1. point, line and area polygon symbols are the basic elements used to create all visual design
Term
Point
Definition
conveys a positon
Term
Line
Definition
exhibit directions as well as position
Term
Area
Definition
exhibits exten, direction, and position - graphically uniform over the area; even color uniform repetition of a point or line symbols
Term
Shape
Definition
regular or geometric shapes, irregular shapes as well
Term
Size
Definition
different geometric dimensions
Term
Color
Definition
hue, value, and saturation
Term
Pattern
Definition
combination of basic reptitive graphic elements produces an aerial graphic effect
Term
Pattern
Definition
Exhibits the characteristics of arrangemetn texture/spaceing and orientation
Term
Arrangement
Definition
shape and configuration of component marks that make up a patter
Term
Texture
Definition
size and spacing of component marks that make up a pattern, fine texture; closely spaced small marks
Term
Design Principles
Definition
  1. Clarity and Legibility
  2. Contents, Information, and Map Space
  3. Visual Contrast
  4. Figure-Ground Organization
  5. Visual Hierarchy
Term
Map Composition and Layout
Definition
  1. Map Elements
title 
Map Legend
Map scale
Map symbols
Credits
  1. Aesthetic of Map Compositon
  2. Visual Balance
Term
Golden Section
Definition
  • it is widely accepted that a rectangle with sides having a proportion of about 3-5 seems to be the most aesthetically pleasing formats
  • in mathematics, a geometric proportion in which a line is divided such that the ratio of the length of the longer line segments to the length of the entire line is equal to the length of the shorter line segment to the length of the longer line segment
Term
Typography/Lettering
Definition
  • used to name places; identify or label objects, provides titles, legends, and other explanatory elements
  • letterform characteristics, size, letter spacing typeface personalities and legibility are important aspects of lettering.
Term
Image Draping
Definition
established technique in GIS. Draping a topographic or thematic map onto a 3-D terrain surface is effective but relies on abstract colors, shading, and symbols. Draping a satellite image such as a digital orthophoto, results in good surface texture and can produce visualizations suitable for depicting landscape-scale vegetation patterns
Term
Geometric Video Imaging
Definition
combines video imaging techniques with geometric registration typically undertaken within a GIS. its rarely used on a production bases due to the difficulty in accurately geo-referencing the photographic video image with the 3-D perspective
Term
VRML (Virtual Reality Modeling Language)
Definition
standard file format for representing 3-D interactive vector graphics designed particularly for use with the world wide web
Term
Moore's Law
Definition
the number of transistors incorporated in a chip will approximately double every 24 months.
Term
Digital Representation of Geographic Data
Definition
  • Geographic Databases are dynamic, not static; allows interactive data analysis
  • data models; methods of data representation
Term
Object
Definition
representation of reality, not the thing itself, it is a model
Term
Feature
Definition
an entity being represented by an object. A defined entity and its oobject representation. this term does not make a distinction between the real thing or the model
Term
Entity
Definition
A real world phenomneon; entities have relationships and attributes which can be spatial or non spatial
Term
Object
Definition
discrete and definite
Term
phenomena
Definition
distributed continuously over a large area
Term
Representing Geographic Space
Definition

approaches to representation of real world in geographic databases; 

 

  • Object based model
  • field based model
Term
Spatial Relationships
Definition
  1. contiguity - next to sharing a border
  2. connectivity- connected to
  3. proximity
  4. closure/ containment
Term
Spatial Attributes
Definition
always interested in location
Term
Time
Definition
component of Berry's geographic matrix
Term
Temporal Relationships
Definition
time, algebra, measurement, relationship
Term
Measurement of Time
Definition
  • Time measurement for objects can be made at an instance which is a measurement of existence
  • can also be made for a duration which is a measurement of evolution, occurence, and permanence
Term
Relationship between Time and Space
Definition
  • spatial changes refer to geometric transformation of an object and includes the change in location, size, orientation and form
  • spatial relationships among objects may change as a function of geometric transformations
Term
Temporarl Attributes of Geographic Process
Definition
  1. Generation Time: time at which object is created 
  2. Duration Time: time during which an object is in existence or is observed
  3. Temporal Significance: important of given event
  4. Temporal Scale: analogous to map scale adapted to time
Term
Logical Organization
Definition
how data are classified and feature coded to facilitate identification of relationships between data items
Term
physical organization
Definition
method by which data items are stored on a computer
Term
Data Classification/classification scheme
Definition
purpose of classification scheme: provide an a priori standard with which individual observations can be observed and recorded during data collection process
Term
Two components of Classification Schemes
Definition
  • Descriptive Names of classes and subclasses
  • Definitions of classes and subclasses
Term
Entity
Definition
spatial object that has specific properties that categorically seperate it from other entities. These properties are known as attributes
Term
Entity class, entity type, or feature class
Definition
collectively, entities that share common attributes
Term
Feature Codes
Definition
process of encoding the values of the entities and attributes to graphical elements during the data collection process
Term
Feature Codes comprised of two components
Definition
  1. Major Code
  2. Minor Code
Term
Major Code
Definition
identifies the entity type to which a particular entity belongs
Term
Minor Code
Definition
Identifies the attributes that an entity has, also referred to as a attribute code
Term
Feature codes may be
Definition
alphabetic, numeric, or alphanumeric
Term
Precision
Definition
function of the number of bits used
Term
Byte
Definition
smallest addressable unit in the computer, an 8-bit data item
Term
Data Item
Definition
basic building block of data organization in the computer, an occurence or instance of a certain characteristic pertaining to an entity
Term
Related Data Items
Definition
data items are occurrences of different characteristics pertaining to the same entity
Term
Record
Definition
a stored record, or tuple
Term
Data File
Definition
formed by grouping a record together
Term

True/False

 

 

Computer processing is based on databases rather than data files

 

Definition
True
Term
Raster Data Representation
Definition
Grid Cells representing areas of the same entity type have identical values or patterns of the values tend to be spatially clumped
Term
Raster Data
Definition
run length encoding raster data compression algorithm
Term
Raster Data Representation Encoding
Definition
Adjacent cells along a row wit hthe same values are treated as a group. Value is stored once together with the number of cells that comprise the run
Term
Clustering
Definition
goal is to reduce seek and latency time in answering common large queries. For spatial databases this implies that objects are adjacent in space and are commonly requested jointly by queires should be stored physically together in secondary memory
Term
Three types of Clustering for SDBMS
Definition
  1. Internal Clustering
  2. Local clustering; and
  3. Global Clustering
Term
Internal Clustering
Definition
to speed access to a single object, the complete representation of one object is stored in one disk page, assuming the size is smaller than the free space on the page. otherwise the object is stored on multiple, physically consecutive pages
Term
Local Clustering
Definition
to speed access to several objects, a set of spatial objects is grouped onto one page
Term
Global clustering
Definition
a set of spatially adjacent object is stored not on one but several physically consecutive pages that can be accessed by a single read request
Term
Clustering
Definition
Design of spatial clustering techniques is more difficult than traditional clustering since there is no natural order in multi-dimensional space where spatial data resides. Also disk storage is logical and is only 1-D device
Term
Clustering
Definition
regarding addressing systems, procedures exist to represent relative locations of the 2 or 3-D kind of 1-D sysstems
Term
Clustering
Definition
  • Distance preserving manner needs to be mapped from higher dimensional space
  • No two points in the space are mapped onto the same point on the line, and should be one to one
Term
Row order (TV)
Definition
total longer path than row prime sequence, every other line is traversed in a reverse direction and have several placves in which neighbors on the path are not adjacent in space
Term
Diagonal and spiral orders
Definition
like the row prime sequence in possessing the property of immediate adjacency
Term
Diagonal Sequence
Definition
mixes up corner and side joins
Term
Spiral Order
Definition
Terminates in the middle, making it impossible to connect other blocks of space
Term
Comparison of Paths
Definition
  1. Total length of the path
  2. variability in unit lengths, where unit length is the distance from one point on the path to the next sequence;
  3. the average distance on the path from the tiles to their neighbors in space
Term
Space Filling curves
Definition
  • Special fractal curves which have characteristics of completely covering an area or volume
  • topological dimension of 2
  • if point is 0-D, not possible to define a 1-D curve passing thru the infiinity point
  • if point is conceptualized as 2-D square the side of which tends toward zero, it is possible to find a curve filling a 2-D space
  • In 3-D a point can then be defined as a small cube for which the side length tends toward zero and the curve as a 3 D curver
Term
Paths as Space Filling Curves
Definition
  1. curve must pass only once to every point in multidimensional space
  2. two points that are neighbors in space must be neighbors on the curve
  3. two points that are neighbors on the curve must be neighbors in space
  4. it should be easy to retrieve neighbors at any point
  5. curver corresponds to a mapping from a multi- to a 1-D space
  6. curve should be able to be used for variable spatial resolution
  7. curve should be stable
Term
Peano or N ordering
Definition
facilitates retrieving neighbors; while neighboring points in space are not always neighbors on the curver, they usually are
Term
Hilber Curve
Definition
passes through all points in a set by means of single length steps only. it meets many of the criteria of an ideal curve, but does not enable the easy retrieval of neighbors. Unstable
Term
Algorithm for the Z curve (peano)
Definition
  1. Read the binary representation of the x and y coordinates
  2. Interleave the bits of the binary numbers into one string
  3. Calculate the decimal value of the resulting binary string
Term
Algorithm for the Hilbert Curve
Definition
  1. Read in the n-bit binary representation of the x and y coordinates
  2. interleave bits of the two binary numbers into one string
  3. divide the string from left to right onto 2-bit strings
  4. give decimal valu, d for each 2 bit string
  5. for each number j in the array i
  6. convert each number in the array to its binary representation, concatenate all the strings in order from left to right, and calculate teh decimal value
Term
Disk access
Definition
Hilbert curvbe method is slightly better than the Z-curve because it does not have any diagonal lines
Term
Block
Definition
square region that is the result of one or more quadtree subdivisions of the original image. a quadtree recursively subdivides space into four equal parts
Term
Handling regions
Definition
Each object can be uniquely representaed by the Z-values of its blocks, Each such z-Value can be treated as a primary key of a record of the form
Term
Space Filling curves for GIS systems
Definition
  1. Make scanning operations more efficient (hardware devices or scanning thru datafiles)
  2. They are used as spatial indexes, simplifying 2-D addressing as 1-D addressing
Term
Vector Data Representation
Definition
  • Vector Data model is object based
  • best utilized to represent discrete objects
  • spatial objects are represented individually and represented mathematically, via coordinates
  • Vector data model is more complex than raster data model
  • Wide variety of formats
Term
Vector Data Representation Formats
Definition
  1. Decomposing spatial objects into basic graphical elements
  2. use of topology (spatial relationships) as well as geometry coordinates
Term
Vector Terminology
Definition
  • Lines (arcs)- begin and end with a node
  • Polygons (areas) - closed loop of coordinates
  • points
Term
Spaghetti data model
Definition
  • not structured vector data from map digitizers, CAD- stores graphical elements, not graphical entities
  • redundant- stored twice
  • must be structured for use in GIs
Term
Topological Data Model
Definition
  • Structured vector data
  • many variants of model - most common is the arc-node data model
  • Arc = line segments
  • node = end points of line segments
  • stores graphical elements rather than graphical entities
  • stored topological relation allows graphic entities to be constructed
Term
Spatial Data Transfer Standard (SDTS)
Definition

robust way of transferring earth referenced spatial data between dissimilar computer systems with the potential for no information loss. it is a transfer standard that embraces the philosophy of self-contained transfers, spatial data, attribute, goereferencing, data quality report, data dictionary

 

Term
Classification and intended use of objects in STPS
Definition
  • Geometry only - for drawing, display and geometrically defined operations on raster and vector data structures
  • geometry and topology - for vector data structures that use geometric drawing and topological operations
  • topology only - for certain analytical operations
Term
Point
Definition
  • a zero dimensional object that specifies geometric locations
  • Entity point - point used for identifying the location of point features such as tower, buoys
  • Label Point - a reference point used for displaying map and chart text to assist in feature identification
  • Area Point- representative point within an area usually carrying attribute information about that area
Term
Node
Definition
zero dimensional object that is a topological junction of two or more links or chains, or an end point of a link or chain
Term
Line and Line Segment
Definition
  • A line is a generic term for a one dimensional object
  • Line segment- direct line between two points
Term
String
Definition
connected nonbranching sequence of line segments specified as the ordered sequence of points between those line segments. A string may intersect itself or other strings
Term
Arc
Definition
a locus of points that froms a curve that is defined by a mathematical expression
Term
Link
Definition
a topological connection between two nodes. A link may be directed by ordering its nodes
Term
Chain
Definition
  • a directed nonbranching sequence of nonintersecting line segments and arcs bounded by nodes, not neccesarily distinct at each end
Term
Complete Chain
Definition
chain that explicity references left and right polygons and start at the end of nodes it is a two dimensional manifold
Term
Network Chain
Definition
chain that explicitly references start and end nodes and not left and right polygons
Term
Ring
Definition
sequence of nonintersecting chains or strings and or arcs with closure. a ring represents a closed boundary, but not the interior area inside the close boundary
Term
Interior Area
Definition
Area not including its boundary
Term
G-Polygon
Definition
area consisting of an interior area, one outer G ring and zero or more non intersecting nonnested inner G-rings. No ring, inner or outer, must be collinear with or intersect any other ring of the same G-polygon
Term
GT polygon
Definition
area that is two dimensional component and only one two dimensional maniforld
Term
Universe polygon
Definition
defines the part of the universe that is outside the perimeter of the area covered by other GT-polygons. This polygon completes the adjacency relationships of the perimeter links
Term
Pixel
Definition
two dimensional picture element that is the smallest nondivisible element of a digital image
Term
Grid Cell
Definition
two dimensional object that represents the smallest nondivisible element of a grid
Term
Two dimensional aggregate spatial objects
Definition
Certain two dimensional aggregate spatial objects must be defined to provide context for many of the simple objects defined above. these aggregate objects are necessary for the definition of raster objects, topology
Term
Digital Image
Definition
Two dimensional array of regularly spaced picture elements (pixels) constituting a picture
Term
Grid
Definition
two dimensional set of grid cells forming a regular tesselation of a surface
Term
Rectangle variant Grid
Definition
Each row and column of the Grid may have independent thickness or width
Term
Layer
Definition
an areally distributed set of spatial data representing entity instances within one theme, or having one common attribute or attribute value in an association of spatial objects. A layer is specifically a two, three, or N-dimensional array of attribute values associated with all or part of a grid, image, voxel space or any other type of raster data.
Term
Raster
Definition
one or more related overlapping layers for the same grid, digital image, voxel space, or any other type of raster data. the corresponding cells between layers are registered to the same raster object scan reference system . The layers overlap but need not be of the same spatial extent
Term
Graph
Definition
set of topologically interrelated zero-dimensional, one dimenional and sometimes two dimensional objects taht conform to a set of defined constraint rules
Term
Planar Graph
Definition
node and link or chain objects of the graph occur or can be represented as though they occur upon a planar surface. Not more than one node may exist at any given point on the surface
Term
Network
Definition
a graph without two dimensional objects. If projected onto a two-dimensional surface, a network can have either more than one noede at a point, and intersecting links or chains without corresponding nodes
Term
Voxel
Definition
a three dimensional object that represents the smallest nondivisible unit of a voxel of space (volume) (think cube)
Term
Voxel Space
Definition
3 D array of voxels in which the volumetric dataset resides. The volume represents some measurable properties or independent variables of a real object or phenomenon.
Term
MetaData/MetaInformation
Definition
  • documents knowledge of data accuracy, provenance, and age necessary for good decision making
  • can build a GIS catalog, internal or external portals allow others to search, find, and access the GIS resources
Term
FGDC
Definition
Federal Geographic Data Committe with the goal to provide a complete description of a data source
Term
ISO
Definition
  • International Organization for Standardization
  • attempts to satisfy the requirements of all existing metadata standards; flexible genearl or detailed descriptions
Term
XML
Definition
  • eXtensible Markup Language was developed by the World Wide Web Consortium
  • standard for designing text formats
Term
GIS
Definition
A GIS is a collection of hardware, software, data, policies, procedures, and people for the input, sotrage, & retrieval, manipulation and analysis, output and modeling of spatially referenced data
Term
Relational DBMS
Definition
  • object oriented database systems
  • Small World
Term
GIS FAct
Definition
Sometimes referred to as a scaleless system but it is not true because you are not changing the original scale that the data was originally collective
Term
Cognitive GIS
Definition
deals with non-euclidean coordinates
Term
Error Propagation
Definition
can amplify or cancel out your operations. Understanding how errors propagate is extremely important
Term
Digital Raster Graph (DRG)
Definition
scanned hardcopy map that has been georeferenced
Term
Line
Definition
Graphical
Term
Chain/arc
Definition
topological
Term
Differential Post Processing
Definition
Most accurate form of GPs
Term
Projection Surface
Definition
  1. Plane (flat surfaces) - azimuthal projection family
  2. cylinder - cylindrical projection family
  3. Cone - Conic projection family
Term
Light Source Position
Definition
  1. Gnomonic- Light source is at the center of the globe (flashlight shing at the center)
  2. Stereographic: light source is at the point exactly opposite of the point of tangency of the projection surface (from the poles)
  3. Orthographic- at a considerable distance (infinite point): Light rays are parallel, often used for persepctive views which means the map is often perspective but not conformal or equal in area.


Term
Normal (regular Projection)
Definition
  • normal orientation for a plane is tangent at the pole (polar azimuthal)
  • cylindrical is normally oriented so that it is tangent along equator (equitorial)

 

  • A cone is normally oriented so that it is tangent along a parallel with its apex over the pole, in alignment with the axis of rotation
Term
Transverse Projection
Definition
  • projection is tuned 90 degrees from normal
  • for a plane, the plane is tangent at the equator
  • for a transverse cylindrical projection, the cylinder is tangent along a meridean
  • transverse conic: not frequently seen
Term
Oblique Projection
Definition
Projection surface lies at an angle somewhere between the normal and transverse position
Term
Tangent Projection
Definition
  • The projection surface is tangent to the globe
  • a planar surface is tangent to the globe only at one point
  • tangent cones and cylinders contact, the globe along a line
Term
Secant Projection
Definition
  • projection surface intersects the globe instead of merely touching the surface
  • a planar surface intersects the globe forming a small circle along the intersection line
  • A cone or cylinder intersects the globe resulting in two small circles along intersecting lines
Term
Standard Point
Definition
  • point at which a planar surface touches the globe
  • only the one standard point exists for a planar tangent projection
  • directions from the point are accurate greate circles passing through are represented as straight lines
  • Distortions of area angle have a circular pattern and increases with distance from standard point
Term
Standard line (line of true scale)
Definition
  • line along which projection surface touches or intersects the globe
  • this is the one standard line when a polar surface intersects the globe or a cone or cylinder is tangent to the globe
  • there are two standard lines when cone or cylinders intersect the globe
  • along a standard line a map has no distortions and map scales is identical to the nominal globe
  • Geometric distortion generally increases with distance
Term
Geodemographics
Definition
demographic information about a population that is spatially consolidated
Term
Exact Interpolators
Definition
  • honor the data points upon which interpolation is based
  •  surface passes through all points whose value is known
  • proximal interpolation, R splines and Krigin methods all honor given data points
  • Kriging may incorporate a nugget effect if so not exact interpolator
Term
Approximate Interpolators
Definition
  • used when uncertainty exists about given surface values
  • utilize belief that in many data sets there are global trneds which vary slowly, overlain by local fluctuations which very rapidly produce uncertainty (error)
  • Effect of smoothing will therefor reduce effects of error on resulting surface
Term
Stoichastic Interpolators
Definition
  • incorporate concept of randomness
  • interpolated surface is conceptualized as one of many that might be observed all of which could have been produced with known data points
  • Kriging is stoichastics because it allows statistical significane of the surface and uncertainty of predicted values to be computed
Term
Deterministic Interpolators
Definition
  • do not use probability theory
  • example: TIN linear
Term
Fuzzy Math
Definition
fuze up, precision up, knowledge up, and is easier to work with
Term
Toblers Law of Geography
Definition
Things closer together in space tend to be more similar than things further apart
Term
Kriging Interpolation Method
Definition
  • geostatistical
  • basis of the method is the rate at which the variance between point changes over space, this is expressed in the variogram which shows how the average difference between values at points changes with distance between points
  • requires characterization of spatial data to set parameters
  • usually more accurate
Term
CAD Models
Definition

RGB

  • most applicable to computer display devices
  • additive based on a mixture of Red, green, blue
  • CAD system viewed as a cube with red green and blue dyes

 

Red + Green = Yellow

Red + Blue = Magenta

Green + Blue = Cyan

Red + Green + Blue = white

None = black

Term
HSV Model
Definition
  • tecktronic developed by HSV system to specify selection of color projection from tints to shades
  • double cone with the central axis forming a lightness progression identical to black and white diagonal line through RGB cube
  • Many color graphic programs specify color based on hue, lightness value, and saturation
Term
HSV Color Model
Definition
  • Hue is given as an angle counter clockwise between 0 and 360
  • lightness value is given as an integer between 0 (black) and 100 (white) and saturation between 0 (gray) and 100 (pure color)
  • triangular slice for each hue can also be viewed as a plane cut from the RGB cube and deforemed into the HSV triangles
  • The transformation is linear- simple equations can be used to transforms HSV specifications into RGB and vice versa
Term
RGB to HSV
Definition
  • colors in the HSV are defined with respect ot normalized red, green, and blue values
  • R= R/ R+G+B
  • G= G/R+G+B
  • B= B/R+G+B
  • R+G+B= 1
Term
Intensity
Definition
I = 1/3 (R+G+B)
Term
Hue
Definition
H= cos-1{1/2 (r-g)+(r-b)/ [(r-g)2+(r-b)(g-b)]1/2}
Term
Saturation
Definition
S = 1-3/ R+G+B [min(r,g,b)]
Term
Range of calculated saturation and intensity
Definition
S and V [0,1] but can be rescaled down to [0,100]
Term
HSV to RGB
Definition
  • normalize the Saturation and Intensity to the range of [0,1] and H to the range of [0,360] 
  • R = 1/3 (1-S)
  • G= 1/3 (1+Scos(H)/Cos60-H
  • B = 2 - (r+g)
  • range of computed r,g,b is [0,1] but can be rescaled [0,255]
Term
.twf
Definition
contians coordinate information
Term
Spatial Frequency
Definition
same occurence in a certain feature
Term
Spatial Data in Raster Structure
Definition
  • almost no coordinates are stores, in fact, there only one coordinate pair that is stored - the origin
  • Block orientation
  • Storage
coordinate pair, cell size, orientation, orientation angle, matrix size # of rows, columns, projection info, scale
Term
  • Disadvantages of Raster
Definition
  • Geometry and topology are limited but implicit in data structure
  • there is no connectivity
  • have contiguity built into arrangement of cells just need to know the numbering scheme and can do proximity analysis
  • Index schemes - order which we are storing data into the system, z scan back and forth
  • Problem: takes time to access the data we want, positions are close in space in sotrage
  • type of index scheme is application dependent
Term

 

Vector Data Organization

Definition
  • Basic Unit - Chain
  • 3 Topological Objects
  • Nodes - 0 dimensional connection between chains
  • Chains - 1 D connection between nodes
  • Polygons - 2-D polygons share chain boundaries
Term
Raster Facts
Definition
  • nodes bound chains
  • chains cobound nodes
  • polygons co bound chains
  • chain is basic unit since it relates to both nodes and polygons
Term
Fully specified chain
Definition
  • From Node (left poly)
  • To Node (Right poly)
  • Chain is given a sense of direction
Term
Nodes
Definition
Id, Point ID, List of Chains
Term
Chains
Definition

ID, from node to node

 

topological information, deep structure

 

Line ID, or point poly - graphical shape info element - surface sturcture

Term
Polygon
Definition
ID, Label Point ID, Chain List
Term
SQL Structured Query Language
Definition
syntax for defining and manipulating from a relational database management system
Term
ArcInfo
Definition
  • does not support SQL
  • Fields- smallest named unit - represents a characteristic

Entity - Record, File, Database

Term
Record
Definition
collection of individual fields, an entry in the database
Term
file
Definition
collection of records
Term
Database
Definition
collection of files
Term
Numeric Fields
Definition
Stores Numbers
Term
Alphanumeric fields
Definition
stores numbers and letters
Term
Kind of Number Fields
Definition
  • data fields
  • money fields - allowing for only two decimal places
  • integers- does not have decimal or fractional part
  • reads- does have decimal or fractional part
Term
Key fields
Definition
  • Primary Index into the Database
  • First Field that data are stored on
Term
Database Architecture
Definition
  • flat field
  • hierarchical 
  • Network
  • relational
  • object oriented
Term
Flat File
Definition
  • a table or spreadsheet
  • one file to hold all the data
  • row records - number of objects
  • columns - fields
  • for 1 kind of object number of attributes = number of columns
  • 2 kinds of objects MxN = land parcels and soil polygons
Term

Disadvantages of Flat Files

 

Definition
  • Dead Space
  • Redundancy
Term
Relational Database
Definition
  • Looks like a flat file
  • tables or files called relations
  • records are called tuples
  • fields are referred to as domains
Term
Organize data into multiple relations
Definition
  • minimizes the redundancy
  • link seperate relations together by redundancy
  • eliminates dead space
  • process of creating a unique table/relations from redundant tables/relations called normalization
Term
Databases Need
Definition
  • A way to add data to a table without having to change the program used to access it
  • to create a system that allows multiple user access while maintaining security
Term
Management System (DBMS)
Definition
system for providing efficient, convenient, and safe multi-user storage of and access to massive amounts of persistent data
Term
Persistent Data
Definition
Data that outlives the software programs that were used to generate them
Term
DBMS
Definition
  • Includes data, software/programs for storing and accessing the data as well as the security measures
  • User- Query - Query Processor - transaction manager- storage manager- data metadata
Term
Transaction Manager
Definition
Enables Entry for new data or allow changes to the Database
Term
Data Model
Definition
describes the conceptual structuring of the data stored in the database
Term
DBMS History
Definition
  • 1970s starter were most hierarchical
  • 1980s relational DB model developed, algebra that describes the model and a calculus for data retrieval
  • 1990s - Object oriented DBs invented
  • 1997 Relational database > hierarchical - took 17 years to surpass hierarchical usage
  • 2000 - relational 60% data in the market

object 5-7%, hierarchical rest of market

Term
2 main types of languages
Definition
  1. Data Manipulating Language
  2. Data Definition Language

 

Term
Data Manipulating Language
Definition
Commands such as SELECT, INSERT, DELETE
Term
Data Definition Language
Definition
Commands for creating the schema stored as metadata
Term
Levels at which DBs can be described
Definition
  1. Logical Level
  2. Conceptual Level
  3. Research Area
Term
Logical Level
Definition
level at which users view the DB
Term
Conceptual Level
Definition
concerned with infor design
Term
Research Area
Definition

Middleware

  • connects individual DBs to other application programs; reconciles the different terms used among the various DBs
  • Allows users to see at the logical level, one DB can perform just one query
Term

Disk Drivers are Rated by

 

Definition
  • Seek Times
  • Read Times
  • DBs are concerned with where data are stored on the disk drive and affects retrieval time - good DBs have their own drivers to efficiently store data
Term
ArcSDE
Definition
  • Arc Spatial Database Engine
  • Relational Model 
  • Examples 
Term
Entity
Definition
like an object or thing
Term
Entity Set
Definition
  • like a class = set of similar entities/objects
  • represented by a rectangle
Term
Attributes
Definition
  • properties of entities in an entity set
  • Represented by an Oval
  • So entity sets turn into tables and attributes turn into columns in the table
Term
Relationship
Definition
  • connect two or more entity sets
  • Represented by diamonds
  • taking represents a relationship set
  • think of this as a table iwth one column for each connected entity set, and one row for each list of entities are connected

 

Term
Multiway (n-ary) relationships
Definition
  • Consider a relationship between students, courses, and TAs
  • if we want to know which TAs are assisting with which students this design will not tell you that
Term
Multiplicity of Relationships
Definition
  • Many to Many
  • Many to One
  • One to One
Term
Beer Diagram
Definition

All of these relationships are many to many (use a round arrow to denote that drinkers have exactly one"

  • many drinkers might like the same beer (many to One)
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