Use Kriging method with a specific condition for open channels?

[arsalanmostaani]

Hi, I would like to model the velocity of water flow in an open channel by Kriging method(I asked the possibility of using Kriging for this aim before and it seems that this method can be used for every condition). I collected my data on the cross section of the channel and depicted as a point data. The scattered data picture is attached and as you see two red and blue sorts of data(blue data have zero value while red data have nonzero value) and the coordinate of each point data is shown in x,y  plane. I try to  run Kriging method in ARC GIS10 with one condition which is: the blue points must have no spatial relation with the other blue points. How can I apply the mentioned condition in ARC GIS10?(I think this condition influences on empirical semivariogram and the weights related to the blue point data)

[NeilAyres]

So that is a cross section, with the blue dots / line being the channel wall / base.

Why not try other (simpler) interpolation methods like nearest neighbor or idw first.

The blue data is just the bounding extent if I have understood your post correctly.

[arsalanmostaani]

yes you are correct. The blue data presents boundary with zero velocity value. The reason I've chosen Kriging is that I think there is a spatial relation between blue and red data points but as I had written I want to ignore only the spatial relations between blue points.

[DanPatterson_Retired]

If the blue dots are to represent nodata, that is quite a bit different than assigning them a value of 0.  If you want to proceed with any interpolation that excludes the blue dots, set your analysis extent to exclude the area outside the area covered by the red dots.

Every interpolation tool in arctoolbox, has an Environments tab.  Inside there you can set the extents of the analysis plus other raster properties.  Once these are set (extent, cell size, snap raster if appropriate, etc), then proceed with the interpolation.

[EricKrause]

If you want to not include some points in the interpolation, you should deselect them instead of using the Extent environment

In Geostatistical Analyst, you can't use the Extent environment to control which points are used in the interpolation.  In nearly every ArcGIS tool, Extent will operate on the input and the output datasets, but Geostatistical Analyst will always use every point to perform the interpolation, and the Extent environment only controls the extent of the output surface.  We use all points regardless of the Extent environment because including input points outside of the Extent will improve the predictions within the Extent, particularly along the perimeter.

[SteveLynch]

The interpolation tools in the Spatial Analyst toolset and those in the Geostatistical Analyst toolset have some overlap in behavior, for example;

• Output Extent (Environment setting) - use all the input features and restrict the output to this extent.
• Mask (Environment setting) - limit predictions to the area defined by the Mask.

Coincident Points (Environment setting) and Parallel Processing Factor (Environment setting) only applies to the tools in the Geostatistical Analyst toolset.

-Steve