We are using the excellent wind direction auto-variable feature of THREDDS,
whereby after defining our 'eastward_wind' and 'northward_wind' we are able to
get the direction and strength map via the layer 'wind'.
my question: we have seen we can ask for the map in various styles, affecting
the colour palette and scale of the underlying wind velocity image. we would
like to know if it is possible to remove altogether the underlying image,
leaving only the wind direction arrows. I have thought about defining a palette
with only a single transparent colour, but I'm not sure if that is possible as
the palettes don't seem to support alpha values.
And perhaps in the same question if anyone has ever investigated having the
arrows to reflect the wind velocity in the typical 'quiver' type way.. this has
probably been discussed before but I can't find any reference.
thanks and regards