ASSESSMENT OF THE HOMOGENEITY OF VOLUNTEERED GEOGRAPHIC INFORMATION IN SOUTH AFRICA

The potential for volunteer groups to contribute geographic data to National Mapping Agencies has been widely recognised. Several investigations have been done to determine the geometric accuracy of this data for the purposes of national mapping. Beyond accuracy, from a production perspective National Mapping Agencies will also be interested in the sufficiency and uniformity of the data. This paper presents an investigation of whether presently geographic data generated by volunteers is uniform across a country and whether the rate of production of data is consistent. For the purpose of the test, changes in data of South Africa from OpenStreetMap are analysed for the period 2006 to 2011. Here only point and line data are considered. The results generally show that the rate at which data is generated varies in space and time. The results also confirm that volunteers emphasise on the capture of certain information and that the capture doesn't average out as might be expected. The results also showed that social events, such as a World Cup, also have the effect of spurring the generation of volunteer geographic data. The implication of these results for National Mapping Agencies is that they cannot treat volunteer geographic information as being of a uniform standard. How National Mapping Agencies respond to this will have to be the subject of other investigations.