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I have xyz points. I have imported these XYZ points into QGIS and need to create a raster from these points. I have used the raster interpolation plugin and I used IDW as the interpolation method. I got this raster (The following snapshot). Why it is like this? How I can fix it?

enter image description here

The average distance between points are 15m. In the above snapshot, the distance coefficient p is 2.

In the below snapshot, the distance coefficient p is 15. I have to mentioned that I used the IDW method.

enter image description here

What distance coefficient p. I need to use.

Any Idea?

  • 1
    What's wrong with it? – user30184 Jan 29 '18 at 13:28
  • These black and white points are the points which i have created the raster based on . why this is like that? – Mike Jan 29 '18 at 16:53
  • The radius that you have used for IDW is obviously rather small. Technically the raster is OK but you may want to adjust your parameters. – user30184 Jan 29 '18 at 16:57
  • Can you please tell us something about your data (source)? – Stefan Jan 30 '18 at 11:49
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The IDW method calculates weighted average of the given points. The weight is inverse proportional to the distance between grid point and known point. P is used in the weight as a power of the distance. So the more you increase P, the less affect has a point to its environment. The usual value for P is 2. I would reduce the resolution of the output raster to the average distance of points and I would reduce P to 0.5-1.5 to have fewer local peeks.

An example P=2

P=2

And P=0.5

P=0.5

You may give a try to triangle interpolation.

0

try to use "rasterize (from vector to raster) instead of interpolation (if you open it as text layer firstly you need to save it as layer file)

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