"True holes" and "false errors": the control of the digitization of shapes of flint formations in the Dordogne department by using a GIS.

In the framework of several collective research projects, a partnership with the Centre National de Prehistoire in Perigueux has achieved digitization at 1:10 000 scale of all flint formations in Dordogne department. This work, carried out with ArcGIS and QGis software, using 1:50 000 scale geological maps scanned and georeferenced, available on BRGM Infoterre web service, enabled the production of a unique database on georesources. Once digitized and uniformly characterized, flint formations are used to view current georesources and therefore to make hypothesis on supply strategies and movements of prehistoric populations. Data on flint formations were uploaded on ArcGISOnLine (AGOL), a mapping web platform of ESRI for sharing securely geo-referenced data. During this step, differences in geometry arose between original data and data after uploading on AGOL platform. A systematic quality control of digitization and transformation of files after their transfer to AGOL platform, has appeared necessary to ensure the data quality for project partners. If this control had not been made, errors of interpretation could have occurred, especially when using functionalities of spatial analysis with these data, for which the quality of geometry is essential. This communication aims to highlight importance of quality control of georeferenced data, not only during their initial digitalization but also throughout their treatments and transfers to various diffusion and sharing platforms.