This is a cross post from Stack Overflow, and DSP at Stackexchange since I cannot really decide which part of Stackexchange is most fitting. If this is the wrong place please tell me and I'll remove the question.
I have a matrix with numerical data. The matrix contains values from 0 to an arbitrary integer value.
Each element of the matrix is equivalent to a coordinate on a map.
I want to display that data as a heatmap overlayed the original map.
The three approaches I have found so far are
Linear interpolation. I guess the interpolation is don from the original datapoint to some set distance away from it in each direction.
Average of surrounding cells. Each empty cell gets the average value of the eight adjacent cells.
Gaussian blur as suggested on the SO thread.
Box blur with 1..n passes.
Are there any more methods? What are the pros and cons of the different approaches? What is a good source, online or print, for a discussion on heatmaps or similar problems?