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PostProcessingandbringingthe DataintoGIS
Butwait
thattoppartoftheroutewasnttherebefore!
Original
Final
Unfortunately,GPSisnotfoolproof
Unfortunately,GPSisnotfoolproof
Butitseasytospotmistakesinthedata
Thereisadrasticchangeineverycolumn
Butitseasytospotmistakesinthedata
Thereisadrasticchangeineverycolumn
PostProcessing
HavingqualityGPSdatasometimesrequires postprocessing
Software,madebytrimbleorotherswilldo thisforyou
Itiseasytodoonyourown,ineitherExcelor GoogleEarthorGIS
PostProcessingTheGPSlogs
apointatthe giveninterval.
Thesoftware drawsapath, asabestfit
line
PostProcessingThepointsandlinesinGoogleEarthare
organizedintofoldersjustliketherestof Windows
Creatingthefinishedproductrequires creatinganewfolder,andcopyingand pastingthedesiredpointsandlinesintoit.
Thetimeittakesdependsonhowlong(in time)yourpathis,andtheinterval.
Thisparticularmapwasanhourlongbus ride,withonepointpersecond=approx3600
points.Itiseasytofindthepathandthebusstops,
becauseGoogleEarthgivesthemdifferent symbols
BringingthedataintoGISforanalysis
DescriptiveFileName.csv
Reformatthedata Itseasierthanitsounds TheGPSunitformatsLatsandLongsdifferently
thanwedotheyjustuseE/W,N/Sinsteadof negatives
GISdoesnotlike/
incolumnheadings,andwill notunderstandtheLatLongcoordinatesunless
theyarereformatted.Change42.687161,N,73.827057,W,To42.687161,73.827057 ThisprocesscanbeautomatedinMSWord
usingtheFindandReplaceFunction.
AddthefiletoGISasnormal
Rightclickonthefile,andclickDisplayXYData Changeittoacoordinatesystemtomatchyour
maporothershapefiles
Dontworrythatyouhavepointssofarawayfromeachother,
everyGPStesthasbadpointsatthebeginningandtheendof therun
(Thisdatawasnotpostprocessed)
Onceyoufindthevaliddata,zoominandyou willfindwhatyouarelookingfor
Ifyouhavedoneeverythingcorrectly,adding otherlayerstothemap,suchasStreetmaps, shouldlineupperfectly.
Rightclickthefilename,MouseoverData,andclickonExportData.Addthelayertothe
map.Nowyouwill
beabletoeditthe
dataorrelateitto
othertables.
Post Processing and bringing the Data into GISBut wait that top part of the route wasnt there before!Unfortunately, GPS is not foolproofUnfortunately, GPS is not foolproofBut its easy to spot mistakes in the dataBut its easy to spot mistakes in the dataPost ProcessingPost ProcessingPost ProcessingBringing the data into GIS for analysisReformat the dataAdd the file to GIS as normalSlide Number 13Slide Number 14Slide Number 15Once you find the valid data, zoom in and you will find what you are looking forIf you have done everything correctly, adding other layers to the map, such as Streetmaps, should line up perfectly.