Geodetski Vestnik (Jan 2013)
Reliability analysis of interpolation methods in travel time maps – the case of Warsaw ; Statistična analiza zanesljivosti interpolacijskih metod na karti časovne dostopnosti – primer Varšave
Abstract
Describing the accessibility, by public transport, of a given place is of particular importance today. The speed and multiplicity of urban public transport have made many places far more accessible than they were at the beginning of the 20th century. Descriptions of the accessibility of a given place, expressed in terms of travel time, have been carried out since the 19th century, when the first map for journeys to London by public transport was published. Since then, many “accessibility maps” have been produced and the theoretical principles for their creation drawn up. However, the influence that particular methods for interpolating travel times have on the accuracy and appearance of such maps has not been analysed. The purpose of this article is an analysis of interpolation methods, using a tool such as GIS, for estimating the accessibility of any location. The research was conducted by the Military University of Technology in Warsaw (MUT), drawing up an isochrone map that showed travel times by public transport to the MUT campus. According to the results, the lowest mean absolute percentage error (MAPE) and mean absolute error (MAE) were shown applying the IDWmethod, in which small isochronic islands did not appear. The highest estimation errors occurred with the nearest neighbour method, and the least beneficial arrangement of isochronic islands appeared using the spline method ; Določanje dostopnosti območja s sredstvi javnega prevoza je zelo pomembno. Zaradi velikosti in hitrosti sredstev mestnega prevoza so marsikateri kraji bolj dostopni kot na začetku 20. stoletja. Strokovnjaki so določali dostopnost območja, ki jo izraža čas prispetja na cilj, že v 19. stoletju, ko so izdali prvo karto javnega prevoza v Londonu. Od takrat je nastalo veliko kart dostopnosti. Poleg tega imamo na voljo teoretična pravila oblikovanja kart. Kljub temu nismo še analizirali vpliva metode interpolacije časa vožnje na točnost in obliko kart dostopnosti. Cilj tega prispevka je analiza metod interpolacije, ki so na voljo v programih tipa GIS, za aproksimacijo dostopnosti na poljubnem kraju. Raziskava je bila opravljena na višji šoli Wojskowa Akademia Techniczna (Vojaška tehniška akademija). Njen namen je bil oblikovanje izohron, ki prikazujejo čas vožnje z javnim prevoznimi sredstvi na akademijo. Izidi so dokazali, da je najmanjša napaka interpolacije značilna za metodo IDW, čeprav ta metoda ne registrira majhnih izohronih otokov. Največ napak interpolacije je bilo v metodi »najbližjega soseda«, najmanj koristna lega izohronih otokov pa je bila v metodi »spline«.
