Sampling mutliple data around a specific point

I have a large number of xyz data. I need to find the nearest equivalent data points within this data set to some coordinates. I.e. I need to find all the nearest xyz data which "surrounds" each coordinate, and then sample this data cloud. Currently, my code can sample the nearest xyz data point to a coordinate, but not all that surround it.

[nr, nc]=size(field);
for i=1:nr
  [~, index]=min(abs(model(:,1)-field(i,1))+(abs(model(:,2)-field(i,2))+(abs(model(:,3)-field(i,3)))));
  output(i,:)=model(index,:);
end

Is it as simple as creating another loop, or is there a function that allows me sample a data cloud? I've not found anything that seems appropriate.

Many thanks in advance!