Dear Jean, you need to interpolate your point information to a raster and then you may extract isohypes based on the grid. Regards, Christine Weijers, Jean (Kerkrade) wrote > Is there a tool in qgis to convert point information to isohypes? -- Sent from: http://osgeo-org.1560.x6.nabble.com/QGIS-User-f4125267.html