Help On kiring

[MinaRahimi]

Hello,

I want to do interolation from points to create surface in raster format. I used ordinary kriging to do that. The final surface which is in a layer format seems reasonable. However, when I export it to raster and add the raster, it looks weired which I've attached.

I've changed lag size and lag number but the raster ones still look weired.

Does anyone can help me in this regard? What is wrong that I cannot get smooth surface?

Thanks,

[EricKrause]

The raster looks fine to me.  What is concerning you about the raster?

One thing to keep in mind is that the geostatistical layer will look different after exporting to raster.  This is because the geostatistical layer uses a quick contouring algorithm to give fast results.  The contours are not exact.  If you want to make the contours more exact, you can right-click the geostatistical layer and choose "Properties..."  On the Symbology tab, there's a checkbox for "Presentation quality".

When you export to raster, the software makes a prediction at the center of every raster cell.  Depending on the data and the kriging model, the raster surface may appear different than the geostatistical layer.

[MinaRahimi]

Hello Eric,

Thanks for the answer.

If you zoom in the image, you will see that some break line in the raster output and it doesn't look smooth. I've done interpolation with the same points with IDW and it is smoother than ordinary kriging.

Also, I checked my data points and I found out that they don't have normal distribution. So, I used Simple kriging to normalize the data. I've attached the result of simple kriging. If you compare these two images, you will see how the output of simple kriging smoother than ordinary kriging. I am wondering if the problem is normal distribution of the data or not?


Thanks again,

Mina

[EricKrause]

You can get choppy results like that at the boundary of searching neighborhoods, and having data that is not normally-distributed will generally make this worse.  I suggest you stick with the Simple Kriging results, but if you want to use Ordinary Kriging, try using a Smooth searching neighborhood, or increase the minimum number of neighbors (these options appear in the Geostatistical Wizard on the screen after the semivariogram).

[MinaRahimi]

Eric,

I increased the minimum searching neighbor and it works fine.

Thanks for your help.

Mina