Geographical Information Geographical Information Systems (GIS)Systems (GIS)

Week 3 (21/02/07)Week 3 (21/02/07)

© Richard Haddlesey www.medievalarchitecture.net

Lecture aimsLecture aims

To build on the concepts of DBMS learnt in To build on the concepts of DBMS learnt in previous lectures and to apply geo-referencing to previous lectures and to apply geo-referencing to themthem

To familiarise the student with the concepts of a To familiarise the student with the concepts of a GISGIS

To learn the key features of using ArcGIS 9To learn the key features of using ArcGIS 9

programmeprogramme

Week 3Week 3• Define what we mean by GIS and why it is

useful in archaeology• Discuss the development of GIS in archaeology• Discuss appropriate hardware and software

systems, their advantages and disadvantages• Introduce co-ordinate systems• Provide some background to the module case

study

ProgrammeProgramme

WEEKS 4-7• Consider Raster and Vector graphics• Discuss the use of databases in GIS• Examine 3D applications

What is a GIS?What is a GIS?

Geographical Information Systems / ScienceGeographical Information Systems / Science

"... "... a powerful set of tools for collecting, storing, a powerful set of tools for collecting, storing, retrieving at will, transforming, and displaying retrieving at will, transforming, and displaying spatial data from the real world for a particular spatial data from the real world for a particular set of purposes." (Burrough 1986)set of purposes." (Burrough 1986)

A GIS is a computer system capable of capturing, A GIS is a computer system capable of capturing, storing, analyzing, and displaying geographically storing, analyzing, and displaying geographically referenced information; that is, data identified referenced information; that is, data identified according to location.according to location. (USGS website (02/2007)) (USGS website (02/2007))

What is a GIS?What is a GIS?

Spatially referenced database Spatially referenced database (geodatabase)(geodatabase)

Integrating technologyIntegrating technology• Computer Aided Mapping / Computer Aided CartographyComputer Aided Mapping / Computer Aided Cartography• Image Processing, particularly of remote sensed dataImage Processing, particularly of remote sensed data• Computer graphics / data visualisationComputer graphics / data visualisation• Spatial analysis and statistical softwareSpatial analysis and statistical software• Database technologyDatabase technology

What a GIS is notWhat a GIS is not

A software packageA software package

A mapA map

A GPS (Global Positioning System)A GPS (Global Positioning System)

Key GIS Concepts Key GIS Concepts

A geographic information system is a A geographic information system is a system for the management, system for the management, analysis, and display of geographic analysis, and display of geographic datadata• Maps and globesMaps and globes• Geodatabases (DBMS)Geodatabases (DBMS)• Logic workflowsLogic workflows• metadatametadata

Key GIS Concepts Key GIS Concepts Marble (1987) defined four subsystems:Marble (1987) defined four subsystems:

1.1. Data Entry Data Entry handles all the translation of raw or partially processed handles all the translation of raw or partially processed spatial data into an input stream of known and carefully controlled spatial data into an input stream of known and carefully controlled characteristics,characteristics,

2.2. Data Storage and Retrieval Data Storage and Retrieval subsystem or spatial database. This is subsystem or spatial database. This is responsible for storing spatial, topological and attribute information, responsible for storing spatial, topological and attribute information, and maintaining links with external database systems,and maintaining links with external database systems,

3.3. Manipulation and Analysis Manipulation and Analysis takes care of all data transformations, takes care of all data transformations, and and carries out spatial analysis and modelling functions,carries out spatial analysis and modelling functions,

4.4. Visualisation and Reporting Visualisation and Reporting subsystem returns the results of subsystem returns the results of queries queries and analyses to the user in the form of maps and other and analyses to the user in the form of maps and other graphics as well as text.graphics as well as text.

5.5. We might also add a 5. We might also add a 5. User interface User interface to this listto this list

The importance of GISThe importance of GIS

The British Government (Dept. of the Environment) stated in 1988 that the impact of GIS on spatial analysis was as significant as ........

“the invention of the microscope and telescope were to science, the computer to economics and the printing press to information dissemination. It is the biggest step forward in the handling of geographic information since the invention of the map”

Why use GIS in archaeology?Why use GIS in archaeology?

Archaeology is a spatial disciplineArchaeology is a spatial discipline

We work in all 3 dimensionsWe work in all 3 dimensions

It allows us to re-examine past theoriesIt allows us to re-examine past theories

Allows us to analyse several maps in one Allows us to analyse several maps in one easy package and select specific data easy package and select specific data attributes using layersattributes using layers

Spatial informationSpatial informationSpatial phenomenon Explanatory factorsSeasonal Hunter-Gatherer camps within a landscape

The availability of resources

A hierarchy of settlements within a region Territorial spacing and proximityto market

The distribution of watchtowers along a defensive structure (e.g. Hadrian’s wall)

Carefully structured and formalised intention linked to a specific functional requirement

The location of coarse potsherds in the plough soil The result of a number of quasi-random post-depositional forces

The position of a zone of decoration on the body of a ceramic vessel

The physical manifestation of asymbolic-ideological design

The arrangement of earthworks and stones at a Neolithic henge site

The unplanned, accumulatedproduct of everyday ritual practice

The suggested zodiacal arrangements of monuments around the site of Glastonbury in Southeast Britain

The tendency of the human eye to see structures in apparently random patterns of dots

Discard of bone debris around a hearth The functional requirements ofbone-marrow extractionundertaken whilst sitting around asmoky fire

The Nazca lines and geo-glyphs Processional routes and pathways

Adoption of GIS in archaeologyAdoption of GIS in archaeology

Adopted by US archaeologists, mainly CRM (e.g. Adopted by US archaeologists, mainly CRM (e.g. Kvamme) for ‘Predictive modelling’ of site locationsKvamme) for ‘Predictive modelling’ of site locations• Reflects type of the archaeological work and theoretical orientationReflects type of the archaeological work and theoretical orientation• Still a major topic of investigation in the US e.g. Westcott & Brandon Still a major topic of investigation in the US e.g. Westcott & Brandon

Adoption Adoption

later in the UK, then other European countrieslater in the UK, then other European countries• In Europe, the impetus for GIS adoption was more from researchers In Europe, the impetus for GIS adoption was more from researchers

than managersthan managers• Little interest in predictive modelsLittle interest in predictive models• Far more ‘analytical’ uses of technologyFar more ‘analytical’ uses of technology• Potential for GIS for archaeological management quickly realised, Potential for GIS for archaeological management quickly realised,

although implementation remains limitedalthough implementation remains limited

How do we communicate How do we communicate the location of something to the location of something to another person?another person?

What happens if that place What happens if that place is not in Britain?is not in Britain?

Jones 1997, chapter 4

Co-ordinate systems (1)Co-ordinate systems (1)

Cartesian co-ordinates

Easting

Nort

hin

g

Polar Planar co-ordinates

Dista

nce

Angle

You will be familiar with two co-ordinate systems:

Co-ordinate systems (2)Co-ordinate systems (2)Both the previous two systems are fine over short distances as both assume the world is flat

Parallel

Meridian

Co-ordinate systems (3)Co-ordinate systems (3)Map Projections: transforming a representation of the world in 3D to a representation on a planar surface

The Mercator projection has straight meridians and parallels that intersect at right angles. Scale is true at the equator or at two standard parallels equidistant from the equator. The projection is often used for marine navigation because all straight lines on the map are lines of constant azimuth

Co-ordinate systems (4)Co-ordinate systems (4)Transverse Mercator projections

Transverse Mercator projections result from projecting the sphere onto a cylinder tangent to a central meridian. Transverse Mercator maps are often used to portray areas with larger north-south than east-west extent. Distortion of scale, distance, direction and area increase away from the central meridian.

49o N, 2oW

Scale 0.996

The Universal Transverse Mercator (UTM) projection is used to define horizontal positions world-wide by dividing the surface of the Earth into 6 degree zones, each mapped by the Transverse Mercator projection with a central meridian in the centre of the zone. UTM zone numbers designate 6 degree longitudinal strips extending from 80 degrees South latitude to 84 degrees North latitude. UTM zone characters designate 8 degree zones extending north and south from the equator

Co-ordinate systems (5)Co-ordinate systems (5)Transverse Mercator projections

Any problems with projections?

Co-ordinate systems (6)Co-ordinate systems (6)

The shape of the Earth (geoid) has been refined a number of times. Each change affects all projected co-ordinate systems

Case studyCase study

Moncayo Archaeological Survey

Moncayo Archaeological Survey (east of Magallón)

Neolithic and Bronze Age activity

Sites on surface on plateau and in gully sections

Neolithic site at Cabezo Agudo

Ambel study area

Valdequnquera Valley

Fuente del Ojo

Sequences below Fuente del Ojo

Sequences below Fuente del Ojo

Valdequnquera Roman villa

Valdequnquera Roman villa (fieldwalking finds)