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"Kernal Interpolation with Barriers" producing cell values not equal to input points.

Question asked by geonetadmin on Apr 5, 2013
Latest reply on Apr 5, 2013 by geonetadmin
Original User: SHopk

I'm currently working on a project involving interpolation of water quality values (taken at monitoring stations) within a river polygon. The monitoring stations are fairly widely spaced, requiring me to have a large bandwidth value to ensure that the interpolation reaches each station. This value typically needs to be around 25km in order to produce an output that leaves no null gaps along the interpolated section of the river. Unfortunately this has left me with interpolated values that are very different from the known point values that the interpolation is based on.

In the first pic you can see that the point has a value of 0.005, while the cells of the output raster around the point have a much higher value, 0.126. In the second pic you can see a cluster of points with values of around 0.4, but the resulting raster has a value of only 0.134. The values seem to correctly become higher and lower as they approach/leave higher or lower value points, but the actual cell values are drastically different than the known points.

Is there a way to have the interpolation maintain the known values at the monitoring station points while still producing a raster that encompasses the entire study area?

Any help is appreciated.