Expanding/Extending Nearest Neighbor Interpolation beyond input data points

TylerBragg

Ok.  So i've been working on this from a number of directions, and none seem to work.  Here's what I'm doing:

I have a point shapefile that contains values that I want to interpolate into a raster to conduct futher anaylsis.  You could call these "elevation points".  The trick is, I need the Nearest Neighbor Interpolation to extend beyond the points a distance of 3 miles.  This might sound easy, but as I dig deeper, it turns out that it is not (or I can't find the way to do it that makes it easy). 

I have a 3 mile buffer polygon shapefile created, and have tried using it as the "analysis extent" multiple times in a number of differnt ways:  Environment settings in both the 3D analysis and Spatial Analyst tools in the toolbox, and in the "options" section within their individual toolbars.  I have used both the toolbox tools and the tools available on the toolbars for 3D and SA. I also tried to set it as the analysis mask, that didn't work either.  And I have tried every combination of using both the analysis mask and the extent (both at the same time, one at a time). 

I have been assured by ESRI staff that this works, but I cannot seem to prove them right. 

Additionally, I have attempted to create a TIN using the same methodology, then interpolate to raster from there.  I even tried to edit the TIN with my buffer file so it extends the analysis area, but I can't seem to get it to work right.  If I use "no values" for the height field in the "Edit Tin" tools (for my buffer), and set it to "softclip" --I've tried a number of other SF_Types as well-- It will clip my TIN to the buffer, but only inside of the main extent of the point shapefile--it won't extend beyond the file like I want.  On the other hand, if I use the "ID" field as the height value for my buffer file, the TIN does extend to the extent of the buffer file; unfortunately, the ID is "0", which makes the outer edges of my TIN wrong. 

I have searched far and wide in the forums, but haven't found this problem. 

Oh, and by the way--this process does work in MapInfo using their Nearest Neighbor Interpolation by means of the use of a "Hull", which is a user defined polygon that you can draw and the interpolation will extend to the confines of this polygon, no matter how far outside your "point extent" the hull resides.  We are trying to get the same thing to work in ESRI, but my colleagues and I can't seem get it to work.  Any help is appreciated.

Tyler

ChrisVan_de_Ven

It's now 4 years after this question was submitted, and I'm running into the same problem. I think that in the past, I've used either analysis extent and/or mask to interpolate beyond the input data points, but I currently have a file that I am unable to do this. If you found a solution, please pass it along.

Thanks,

   (a different) Chris