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