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This transformation function is used to interpolate data stored as a track to a grid. This track should consist of three scalar time series: latitude, longitude and values. The transformation function takes the three track input time series and links each output value (each combination of grid cell and time) in the output series to a list of track values (exactly those values for which the coordinates are contained in the grid cell and the track time is closest to this time). A statistical function is then applied to this list of track values to obtain a value for the output time series. Currently only min and max are available. Note that the transformation expects the latitude and longitude for the track to have geoDatum WGS 1984, and expects the grid to have this geoDatum as well.
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