Key Concepts in Geographic Information Systems (GIS)

GISystem

A platform for storing, managing, analysing and visualising spatial data

GIScience

The discipline/field of using spatial data analysis and visualisation techniques to solve problems

GeoSpatial science

Measurement, management, analysis and presentation of spatial data in order to understand processes in the natural and built environments

Vector

Points, lines and polygons that capture discrete geographic features

Raster

Grids and images capturing continuous phenomenon

AI

Built by people and trained on data made by us, they are bias but can be useful

Geospatial professionals responsibility is to

Use the appropriate tools for the job, access uncertainty and encourage appropriate use of the spatial analysis results

What are the two types of spatial data sources

Primary and Secondary

what drives spatial data requirements in GIS?

The GIS question and project goal

What are examples of secondary data sources

Scanned maps, digitised hard copy maps, converted data

what are examples of primary data collection

Raster: Remote sensing, aerial/satellite imagery

What should be considered when evaluating data usability?

Source reliability, metadata, scale, format, resolution, and if it is 'fit for purpose'

Crowd sources

Communally created mapping features

Remote sensing

Measuring the properties of objects without direct contact

Rasterization

Converting vector data to raster data - from points/lines/polygons to grid cells

What are the 3 Vs of Big data?

Volume, Velocity, Variety

What ethical challenges are associated with Big data?

Privacy, consent, bias, surveillance, data misuse

What is open data?

Data that is free to use, reuse, and distribute, with minimal restrictions

Potential issues with metadata

Lack of metadata, low data quality, not user-friendly formats and costs in preparing/maintaining the data

What is VGI (Volunteered Geographic information)?

Spatial data contributed voluntarily by individuals

Unethical GIS use

Lying with maps, surveillance, war planning, data misrepresentation or omission, not citing sources

Gerrymandering

The manipulation of boundaries to favour one party or class

What is metadata and data management?

Data about data (how, when, where, and by whom the dataset was collected)

Why is metadata important in GIS?

Enables discovery, interpretation, sharing, and evaluation of spatial data

What are the main types of metadata?

Descriptive: content-related, Structural: Data format and layout, Administrative: Technical info

What are common metadata standards?

Dublin Core, ANZLIC (AUS/NZ), ISO 19115, ASCII, OGC

What is an SDI (Spatial data infrastructure)?

A framework for accessing, sharing, and managing spatial data across organisations

What is the role of file naming conventions?

Makes data easier to find, identify, and manage

What are common GIS file formats?

Shapefiles (.shp), KML (Keyhole Markup Language), ArcGIS Geodatabase, Web mapping services (WMS/WMTS/WFS)

What is ANZLIC's goal?

To promote consistent, accessible metadata and spatial data use in NZ/AUS

What is Neogeography?

The creation of non-traditional geographic products using techniques and tools outside of traditional GIS

What are location-Based Services (LBS)?

Information services provided by a device that knows its location and modifies the information it provides based on knowledge

What is Mobile GIS?

GIS used on mobile devices, enabled by wireless communication, sensors, and compact hardware

Web GIS

Visualising, querying, and accessing mapping elements online, often via distributed networks and multi-user databases

What is distribution GIS?

GIS components (Hardware, Software, Data, Users, Procedures, Network) located in different places, allowing for scalability and up-to-date data

What are GI (Geographic information) services?

Remote GIS functions provided by servers, such as routing, weather, and elevation data, accessible via the internet

What are the main OGC web service standards?

Web Map Services (WMS), Web Feature Service (WFS), Web Coverage Service (WCS), and Web Map Tile Service (WMTS)

What is SOA in GIS?

Service Oriented Architecture - provides opposite GIS services by requesting and combining data from multiple sources

What is Virtual Reality (VR) in GIS?

Immersive 3D environments where data replaces senses, allowing remote inspection and measurement

What is Augmented Reality (AR) in GIS?

Overlaying digital information onto the real world, via devices like AR glasses

Name some issues with mobile GIS

Battery life, WiFi issues, security concerns, limited spatial/temporal coverage, and potential reduction in spatial memory due to reliance on GPS

What is cartography?

The art, science, and technology of making maps

What is the map design process?

Involves context, audience, type of map, scale, projection, message, and available resources

What is map composition?

The arrangement of map elements for clarity, visual balance, and effective communication

What is visual balance in map design?

Harmonious arrangement of map elements so that none overpower others, achieved through size, value, and placement

What is the figure-ground phenomenon?

Perception organises the map into clear focus entities and backgrounds

What techniques improve map composition?

Closure, vignetting, line contrast, texture/value contrast, and provision of detail

What is map symbology?

The use of graphical elements to represent geographic features on a map

What are Bertin's cartographic variables?

Size, value, texture, colour, orientation, and shape

What is generalisation in cartography?

Simplifying features to maintain clarity at smaller scales, using techniques like simplification, displacement, aggregation, and smoothing

How do you select symbology for thematic maps?

Based on the type of data and the message you want to communicate

What are the 2 types of generalisation?

Semantic (conceptual) and geometric

What does the Douglas-Peucker algorithm do?

Simplifies lines by reducing the number of points while retaining shape

Define Typification

Representing the character of a feature without exact detail

Displacement in map generalisation

Moving features to prevent overlap and improve legibility while maintaining topology

What is the purpose of smoothing in maps?

To reduce angularity in lines for aesthetic and readability reasons

What is amalgamation/combination?

Merging multiple features into one to reduce clutter and improve clarity

What is reduction in generalisation?

Simplifying line or shape complexity while retaining overall form

What is collapse/exaggeration in mapping?

Converting features to simpler forms or enlarging them for visibility

What is roughening used for?

Enhancing natural feature realism using fractal geometry

What is a thematic map?

A map that emphasises the spatial distribution of a single variable

Name the types of thematic Maps.

Dot map, Proportional symbol, Flow map, Choropleth, Cartogram, Isarithmic map

Choropleth map

Standardised areal data like rates or proportions

Cartogram

Area is resized to reflect a variable, not geographic size

Isarithmic map

It uses continuous lines to represent 3D data volumes, such as elevation or pollution

Flow map

Showing movement like migration or traffic, often with directional arrows

Proportional symbol map

Symbols are sized proportionally to the data value at each location

Dot map

Showing incidence and density; dots represent a certain quality and are spatially placed

Geo-referencing properties

Unique, Shared meaning, Persistent through time

Geographic vs Projected coordinate system

Geographic uses latitude/longitude; Projected uses systems like UTM/TM for flat map representations

Geocoding

It's a process of converting addresses into geographic coordinates

Prime Meridian establishment

Chosen during the 1884 International Meridian Conference to standardise global time and navigation

Graticules

A network of latitude and longitude lines on maps

DMS to decimal degrees conversion

DD= degrees+(minutes/60)+(seconds/3600)

Great Circle Route

The shortest distance between two points on a sphere

Scilly Isles naval disaster significance

It highlighted the critical need for accurate longitude measurement

Universal Transverse Mercator (UTM)

A projected coordinate system dividing the world into 60 zones, each 6 degrees of longitude wide, with metric coordinates

Conical and Cartesian projections

For converting spherical surface features onto a 2D pane using geometric grids suited to the maps purpose

What is the shape of the Earth approximated as in GIS?

An oblate spheroid (Ellipsoid)

What is a geodetic datum?

A combination of an ellipsoid, original, and coordinate system used to approximate earth

Why is Web Mercator used in Web GIS?

For fast tile rendering and shape preservation at large scales

What are EPSG codes

Standardised identifiers for coordinate reference systems, projections, and geodetic parameters

What are the current and old NZ projections?

Current: NZTM; Old: NZMG

What is georeferencing?

The process of associating geographic data with specific locations on earth

What is an ellipsoid?

A smooth mathematical surface approximating earths shape

What is a geoid?

A more complex model that accounts for earths gravity to define mean sea level

What are the 4 classes of map projection distortion?

Shape (Conformal) Area (equal-area) Distance (equidistant) Direction (azimuthal)

What are some challenges with georeferencing natural features?

Boundaries may be vague, discontinuous, or vary by interpretation

What are the steps to building a geo-referencing system?

Approximate surface model -> map projection -> coordinate system

What is the difference between local and global datums?

Local datums are optimised for specific areas; global datums are for worldwide use

Why are datums important in GPS and GIS?

They ensure consistent positioning by aligning spatial data to a reference

What are data models in GIS?

Ways to represent spatial phenomena digitally in a computer

What are the two conceptual models in GIS?

Field model and object model

What does the field model represent?

Continuous variation across geographic space

What does the object model represent?

Discrete spatial features like buildings or roads

What is abstraction in GIS?

Simplifying the real world to focus on relevant details for analysis

What are the issues with non-topological vector data?

Redundant boundaries, difficult integrity checking, and lack of spatial relationship encoding

What is a topological data model?

A vector model that stores spatial relationships explicitly

What is the 'spaghetti' model?

A non-topological format where features may cross or overlap without defined relationships

What is a data format in GIS?

The way spatial data are stored, accessed, analysed, and visualised