I'm currently tinkering with MapServer to see if it could work as a backend for the remodel of my hobby stormchaser website. Is it possible (in MapServer) to find all high and low spots in a raster grid and put a label on them. Obviously, I'm trying to make an atmospheric pressure map with "H" and "L" markers. I know how to find the highest and the lowest value in a grid with GDAL but I basically want to find all points which are highest/lowest among all their neighbors. A solution inside of MapServer would be preferred but I wouldn't be opposed to some preprocessing script.