Select four surrounding grid points

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James on 14 Feb 2013
I have the latitude and longitude location of a certain observation and a square latitude and longitude grid of model data. I need to calculate a bilinear interpolation of the 4 model grid points surrounding this observation to the observation. However I'm stuck on how to select these surrounding 4 grid points? Any ideas as to how I could do this in Matlab would be appreciated?
I've tried calculating the actual distance from the observation location and then selecting the 4 nearest points but I realised this doesn't necessarily select the 4 surrounding points.

Answers (1)

Matt J
Matt J on 15 Feb 2013
INTERP2 or griddedInterpolant() will do the entire interpolation operation for you.
Matt J
Matt J on 17 Feb 2013
Edited: Matt J on 17 Feb 2013
There appear to be a lot of contradictions now in what you're saying. Initially, you seemed to be saying that your lat(i,j) and lon(i,j) matrices do not contain plaid sample locations, as output from ndgrid/meshgrid. If they are not plaid, how can the data not be scattered? If they are plaid, there's no need to go through meshgrid/ndgrid. You should be able to use them in interp2/griddedInterpolant as is. They're either plaid or they're not plaid. They can't be neither or both. So which is it?

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