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Looking at a NetCDF file that contains a subdatasets for the variables temp, lat, lng and a couple others

Temperature (4 dimensions)

  • depth (20)
  • time (240 time steps)
  • x (38 pixels)
  • y (53 pixels)

Lat (2 dimensions)

  • x (38 pixels)
  • y (53 pixels)

(the value is the Lat - i.e. the y - coordinate)

Lng (2 dimensions)

  • x (38 pixels)
  • y (53 pixels)

(the value is the Lng - i.e. the x - coordinate)

After processing NetCDF variables into PostGIS via raster2pgsql, I find WRT to these variables:

  • Temperature: 4800 bands (i.e a 2D grid per depth per time step)
  • Lng: 1 band (i.e. a 2D grid)
  • Lng: 1 band (i.e. a 2D grid)

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I would like to run the ST_Contour function on the temperature raster (band 1), but I somehow need to associate the grid position of the values with a value from the coordinate dimension.

In other words I need to 'join' values in the temperature (band 1) raster to values in the Lat and Long rasters.

What are the best ways of doing this? (The lat/lng values are unique per pixel in the band 1 temperature raster)

My current idea is to:

  • Use ST_PixelAsCentroids to generate X/Y coordinates per value as rows
  • Join Lat/lng columns using X/Y values
  • Group values into 'buckets' - with each row in the output table now representing a list of coordinates that make up a polygon

But if there is a way to use ST_Contour directly I think that would be better (I can't see it)

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