Karl Hennermann School of Environment and Development Session 2: What you absolutely need to know about spatial data Geographic Information Systems

Contents I.Defining GIS II.The world is a set of layers III.Vectors and rasters – representing real world features IV.Where am I? Coordinate systems V.Making maps: cartographic projections VI.Challenges and constraints for GIS VII.Q&A Karl Hennermann,

Contents I.Defining GIS II.The world is a set of layers III.Vectors and rasters – representing real world features IV.Where am I? Coordinate systems V.Making maps: cartographic projections VI.Challenges and constraints for GIS VII.Q&A Karl Hennermann,

Defining GIS GIS is not a software product. Karl Hennermann,

Definition I: GIS is… A computer system capable of holding and using data on geographical objects ESRI (1997): Understanding GIS. The ARC/INFO method. Karl Hennermann,

“... geographical objects” Karl Hennermann,

“...data on geographical objects” Location, location, location Karl Hennermann,

“...data on geographical objects” School locations ( ; ), (322317; ), ( ; ), ( ; ), ( ; ), ( ; ) Flooded area Karl Hennermann,

Definition I: GIS is… A computer system capable of holding and using data on geographical objects ESRI (1997): Understanding GIS. The ARC/INFO method. Karl Hennermann,

Definition II: GIS is… An organised collection of computer hardware, software, geographical data, and personnel designed to efficiently capture, store, update, manipulate, analyse, and display all forms of spatially referenced information. ESRI (1997): Understanding GIS. The ARC/INFO method. Karl Hennermann,

“...hardware, software, geographical data, and personnel to capture, store, update, manipulate, analyse, and display...“ Process view Data CollectionPre-processingData Storage & ManagementAnalysisProduct Generation (maps, reports) Architecture view Hardware Software Geospatial data Personnel & Skills Karl Hennermann,

So, what is GIS about? GIS is not a software product. GIS is about the methods / techniques of analysing data spatially or geographically You do not have to use GIS software for work to count as geographical analysis The software simply allows these methods to be carried out efficiently Karl Hennermann,

Contents I.Defining GIS II.The world is a set of layers III.Describing the real world - vectors and rasters IV.Where am I? Coordinate systems V.Making maps: cartographic projections VI.Challenges and constraints for GIS VII.Q&A Karl Hennermann,

The world is a set of layers Karl Hennermann, Jones, Christopher (1997): Geographical Information Systems and Computer Cartography. Addison Wesley Longman.p30

Contents I.Defining GIS II.The world is a set of layers III.Describing the real world - vectors and rasters IV.Where am I? Coordinate systems V.Making maps: cartographic projections VI.Challenges and constraints for GIS VII.Q&A Karl Hennermann,

Describing the real world - vectors Karl Hennermann, File Image (c) Google

Describing the real world - vectors Karl Hennermann, Image (c) Google Bus stops (Point) Land use (Polygon) Roads (Polyline)

Describing the real world - rasters Karl Hennermann, Logical Data Model 1: Green space 2: Water body 3: Residential 4: Industrial 5: ,1,1,1,1,1,2,1,1,1, 1,1,4,4,1,1,2,1,1,1, 4,4,4,4,1,2,1,1,1,1, 4,1,1,1,2,1,3,1,1,1, 4,4,4,2,1,3,3,3,1,1, 3,3,4,2,1,3,3,3,3,1, 3,3,2,4,4,3,3,3,3,3, 3,2,4,4,4,3,3,3,3,3, 2,4,4,4,4,3,3,3,3,3, EOF File Image (c) Google

Contents I.Defining GIS II.The world is a set of layers III.Describing the real world - vectors and rasters IV.Where am I? Coordinate systems V.Making maps: cartographic projections VI.Challenges and constraints for GIS VII.Q&A Karl Hennermann,

Geographic Coordinate Systems (use on spheres and with GPS) Karl Hennermann, The most common geographic coordinate system is: Decimal Degrees on WGS 1984 In the UK also Decimal Degrees on OSGB 1936 The Geodetic Datum The Measurement Units (almost always DD)

Contents I.Defining GIS II.The world is a set of layers III.Describing the real world - vectors and rasters IV.Where am I? Coordinate systems V.Making maps: cartographic projections VI.Challenges and constraints for GIS VII.Q&A Karl Hennermann,

Making maps: cartographic projections Karl Hennermann, A method by which the curved surface of the earth is portrayed on a flat surface. This generally requires a systematic mathematical transformation of the earth's graticule of lines of longitude and latitude onto a plane. ESRI (2010): ArcGIS Desktop Glossary

Making maps: cartographic projections Karl Hennermann, Transverse Mercator

Making maps: cartographic projections Karl Hennermann, Snyder, John P. (1987), Map Projections – A Working Manual. U.S. Geological Survey Professional Paper Washington. The Transverse Mercator projection

Making maps: cartographic projections Karl Hennermann, There are hundreds of geographic coordinate systems, projections, and projected coordinate systems. Always know what the coordinate system and projection of your data is. How to make the British National Grid: Take a spheroid with the OSGB 1936 spec and project it with Transverse Mercator, using the Greenwich meridian as Central Meridian. Then overlay a projected coordinate system, measuring in meters North and East from the Isles of Scilly.

Projected Coordinate Systems (use on maps) Karl Hennermann, British National Grid: Units: meters Reference point is SW of Isles of Scilly Northing: (meters north of the reference point) Easting: (meters east of the reference point) 1000m

Contents I.Defining GIS II.The world is a set of layers III.Describing the real world - vectors and rasters IV.Where am I? Coordinate systems V.Making maps: cartographic projections VI.Challenges and constraints for GIS VII.Q&A Karl Hennermann,

Challenges and constraints Data Cost, arguing that it pays off, and defining business processes Multiplication of effort, Interoperability, SDIs III.Challenges and Constraints Karl Hennermann,

Further reading Paul Longley, Mike Goodchild, David Maguire, David W. Rhind (2010): Geographic Information Systems and Science. 3 rd Ed. John Wiley & Sons Ian Heywood, Sarah Cornelius, Steve Carver (2011): An Introduction to Geographical Information Systems. 4 th Ed., Prentice Hall Karl Hennermann,

Thank you Karl Hennermann,

Q&A Karl Hennermann,