Exercise4APointtonearestpoint:

1. FromfolderExercise4load-AfricanCountries-Landing_Stations-Cables

2. CheckCRS

3. CalculateCentroids

Vector|GeometryTools|PolygonCentroids

4. SavenewLayerasAfrican_centroids

5. Usethe“Distancetonearesthub”tooltofindthenearestpointonthenearestlandingstation.Processing|Searchfor“Distancetonearesthub”

6. Thiscreatesthenewlayer“Hubdistance”

7. ChecktheattributeTableofHubDistance.Doesitcontainalltheinformationweneed?

8. UsetheNNjoinplugin

9. Checktheattributetable.

DIYExercise4BDistanceMatrix:

1. FromfolderExercise4load-KEN_adm2

2. GenerateCentroids

3. SaveCentroidLayer

4. CalculateDistanceMatrix

Vector|AnalysisTools|DistanceMatrixNote(Distanceisindegrees)Youcouldmultiplydistanceindegreesby111.Thisistheconversionratebetweendegreesandkilometresattheequator.

Exercise4CPointtonearestpolyline:

1. FromfolderExercise4load-AfricanCountries-10mcoastline

2. ConvertCoastlinepolylinestopoints.Processing|Searchfor“Convertlinestopoints

3. UseDistancetoHubtool

4. Weonlyneedthepointsonthecoastthatarethenearesttotherespectivecountry’scapital.RunaSpatialQuery

5. Zoomin

6. Saveas“Africa_coast_nearest”Saveonlyselectedfeatures

7. Addcoordinatesofeachpoint(requiredifyouwanttocalculatedistancetoSlaveTradecenterslateron,instata?)Vector|GeometryTools|Export/AddGeometryTools

8. UseNNjointojoininformationfromthecountry_centroids

9. Savelayer.

Exercise4DBuffer:

1. FromfolderExercise4load-KenyaSchools

2. ChangeCRStoprojectedCRSWGS1984/UTM36NFindfittingUTMzoneforyourareaherehttp://www.dmap.co.uk/utmworld.htmSaveLayerandChangeCRSChangeCRSoftheProjectaswell

3. Vector|GeoprocessingTools|FixedDistanceBuffer

Create1Bufferwitharadiusof300andonewitharadiusof1000(inmeters)

Exercise4eMapAlgebra–CalculatingRuggedness:TherearemanydifferenteTerrainruggednessmeasures.http://gis4geomorphology.com/roughness-topographic-position/ForthisexercisewearegongtocalculatetheRelativeTopographicPositionRTP=(DEMmean–DEMmin)/(DEMmax-DEMmin)

1. FromfolderExercise4load-rasterKenyaDEM-vectorKEN_adm2

2. CalculateFocalstatisticsusingtheprocessingtoolr.neighbours

Processing|searchfor“r.neighbours”

Calculate3newrasterKenyaDEM_min,KenyaDEM_max,KenyaDEM_mean

3. UsetheRasterCalculatortocalculatetheRTP

4F.ViewshedAnalysis(PreliminaryBetaversion)Goal:IdentifyAreaswithmobilephonecoverage.CombineinformationaboutthelocationofTelecommtowers,theirrangeandtheirheightwithDEMinaviewshedanalysis:

Source:http://mapaspects.org/

1. FromfolderExercise4load-rasterKenyaDEM-vectorKenya_Comms_Tower

2. ChangeProjectiontoWGS84/UTMN36

3. CreateBufferwith50kmradius

4. InstallPlugin“ViewshedAnalysis”5. Plugins|ViewshedAnalysis|ViewshedAnalysis6. Chooseobserverheightandsearchradius

7. Newoutputisraster.

8. Convertrastertovector.Raster|Conversion|Polygonize