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I have a points layer and I want to create an interpolation grid with QGIS 2.0. If I use Raster -> Analysis -> Interpolation the extent of the output raster is good (rectangular shape) but it doesn't reflect the original values of the points layer in input. The values of the raster are the result of interpolation calculations.
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If I use Raster -> Interpolation the output file reflects the original values of the input points layer, but its shape is not what I'm looking for. enter image description here

I don't see options to get the "original values" with the first method or to choose the extent of the area with the second one. So, how can I choose the shape-extent of the interpolated raster and, at the same time, be sure that it will reflects the values of the input layer?

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There are many algorithms of interpolation, each one with its characteristics. If you want to limit the results to the original values, you need to choose:

  • the TIN algorithm (with GRASS GIS: v.delaunay + tin.to.raster.py of Antonio Alliegro)

enter image description here enter image description here

With GRASS GIS v.surf.rst and a MASK covering the original points

enter image description here

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    Can you add in the answer how to get the 3D model above ?
    – etrimaille
    Oct 27, 2015 at 5:12
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    @Gustry : Run nviz through grass gis to get visualization of 3d model
    – Sylvain POULAIN
    Nov 20, 2015 at 8:55
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    Running nviz in GRASS GIS not in QGIS (more limited )
    – gene
    Nov 22, 2015 at 18:55

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