Saturday, November 21, 2009

3rd dimension for GRIB smoothing

We already had the surface (2D) smoothing, we now have a time smoothing for the GRIB data.
That means that you can get a better resolution for the GRIB cell (divide the cells, and set the values based on the ones of the cells around), the same is now available for time.
You download a 2 degrees by 2 degrees GRIB, for 3 days, every 24 hours, you can very well render a GRIB of 1 degree by 1 degree (or less), every 1 hour. And it works pretty well (offshore, of course, local coastal phenomenons, like the one shown here, cannot be taken care of by a GRIB).
In addition, some performance issues have been fixed, impacting the GRIB animation. With the previously described feature, we can now generate an animation that shows a frame every hour.
That will definitely minimize the demand on the SSB, when downloading the data at sea.
For example, you download a GRIB file for a given area, with cells 2° × 2°, with a frame every 24 hours. With the smoothing, you can easily display it with a 1° × 1° resolution (or less, your call), and with a frame every 1 hour. The equivalent GRIB would be 2×2×24 times bigger, that it 96 times bigger. That does not sound that great, but you can put it another way: instead of 1 minute to download it, it will take more that 1 and half hour. Sounds more convincing like that!
In addition, the dustlets take advantage of the same feature, you can watch really smooth animations.

Example:
video
A Composite has been displayed
Hide the faxes and place labels
Change the wind display to colors
Play animation, it's anything but smooth

video
Set a (2D) smoothing factor of 3
Looks better for each frame
Play animation, it's still not ideal

video
Now, set the time smoothing factor so it generates a frame every one hour
Play animation, it's now much better, perturbations evolution becomes way clearer.
Vancouver is going to be windy and wet again ;)