I don't think Raster Grid Interpolation and Polygonize are the correct tools for what you pretend.
Did you try the Interpolation Plugin? Make it active in the plugin manager, then check this tutorial: http://www.gistutor.com/quantum-gis/20-intermediate-quantum-gis-tutorials/51-inverse-distance-weighting-idw-interpolation-using-qgis.html Best Luck, Alex On Fri, Aug 5, 2011 at 2:52 PM, M.E.Dodd <m.e.d...@open.ac.uk> wrote: > I have various layers of points from various shapes of sampling (not a > regular rectangular grid) and want to interpolate each of them to produce a > set of raster images. In previous GIS I have used this was generally a > matter of making a boundary then telling the gis the points layer and extent > as shown by the boundary and then trying various interpolation methods to > see which one looked most like the real data. However I have yet to find > suitable tools in Qgis to do this. The raster grid interpolate and > polygonise don’t seem to have suitable options and when I did try them the > output looked rather strange and not what I was expecting as it seemed to > have missed out much of the data. > > > -- > The Open University is incorporated by Royal Charter (RC 000391), an exempt > charity in England & Wales and a charity registered in Scotland (SC 038302). > > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-user > >
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