Monday, December 10, 2007


Based on the Dustlet concept developed by Nick Thompson, we can now visualize the wind of the GRIB files this way. It is rendered through a Java applet. It's a great tool to see at a glance what the current situation is like.

Wednesday, November 28, 2007

GoogleMap & wind Improvements

Some improvements have been added to the GRIB visualization in Google Map

Tuesday, November 6, 2007

Dynamic Patterns

We introduced a while back this concept of pattern. Once you have reshaped all several faxes to fit your needs, you can "replay" the re-shaping step by creating a pattern out of it, so you can apply it again on other similar faxes, stored on your file system. That is pretty convenient, when you use the GetFax utility from SailMail, which stores the downloaded files on your disk.
We have also added some features, allowing you, when you are planning a trip, to download from the UI faxes from the Internet. In that case, you download the fax(es) from the net, save them on your disk, and then apply a pattern on them. Mmmh..., there is room for improvement here!
This is where we've introduced the concept of dynamic pattern, containing the URLs of the faxes to download before applying a pattern on it.
As a result, the picture below is just two clicks away. One to invoke the dynamic pattern, another one to show the result in Google Earth... Google Map behaves the same. Click on it to enlarge.It is made out of three faxes:
  1. North Pacific Surface Analysis
  2. North Pacific 500mb analysis
  3. Central Pacific Streamlines
Notice that this last one has to be rotated 90 degrees clockwise, as it comes from the net on its side. This rotation is now part of the pattern as well.

Wednesday, October 17, 2007

Contour detection in the GRIB

Some areas, like south Pacific, south Atlantic, are apparently not covered by weather faxes, but it is possible to retrieve GRIB files for those regions, as they are computed using a model. In order to have on those binary data a view equivalent to what the weather charts would be showing, it is necessary to detect the contour lines from the GRIB, about the PRMSL, 500mb, waves heights, temperature, or whatever data the GRIB would contain. This is now done, and here is the rendering it makes. I'm not sure the algorithm wouldn't deserve some improvements (actually, I'm sure it will), but it seems to render the data I'm expecting. Click the image (top-right) to enlarge it.
Just for fun, you can also superimpose the contour lines with their equivalent faxes, to see if it matches...
That should be very useful for the areas not covered by the faxes.

Thursday, September 27, 2007

More Google stuff

Still playing with projections and images...
Google Earth and Google Maps can superimpose images on the charts. The problem is that they recalculate the coordinates of the document - an image - based on an Anaximandre (square) projection. The NOAA faxes are available as Mercator projection; so I had this interesting Java exercise to turn an image representing a Mercator projection into an image representing the same data, but using an Anaximandre one. Interesting, indeed. The same operation is probably available for the other projections, we'll see that later.
The Google Earth one is pretty interesting, as you can use it in conjunction with other overlays, like clouds, winds, etc, from different origins. It's quite snappy.

If you have Google Earth installed on your computer, download this kmz file, and try for yourself, it's for the North Pacific. And if you don't have it, you should get it, it's free.
The cloud layer in the picture above can be reached through

Monday, September 17, 2007

GRIB and Satellite Picture

A first version of the software, allowing to superimpose a GRIB file on top of a satellite picture is now available. Calculating the projection was quite a challenge, but it seems to work.
It really relates the wind and the clouds. GOES-12 (Geostationary Operational Environmental Satellites, West) provides very suitable pictures for this kind of exercise. The ITCZ (Inter Tropical Convergence Zone) becomes really obvious, very interesting to see that.
The same kind of superimposition can be done with the faxes received from SailMail, I will very soon give it a try.
The image on the right can be clicked, to see more details.

Tuesday, August 21, 2007

GRIB Files in Google Map

This is a bit of a gadget, but it looks good. A given GRIB frame can be rendered in Google Maps.

Saturday, July 14, 2007

500mb in 3D

The GRIB files can also contain data related to the 500mb charts. A 500mb fax would typically look like this:

It is really supposed to represent the topography of the atmosphere...
Other rendering(s) of the same data might be helpful, like this one:

Plus it is really animated, you can orient it the way you want, just with the mouse.
The four lows are really easy to spot, notice that the one in the Gulf of Alaska is not that impressive, and look - it is not on the fax, it's beyond its edge - how much fun they're going to have in the south Japan...
Sea temperature and PRMSL (Pressure at Mean Sea Level) can also be represented the same way. I want to check if wave heights can be represented the same way...

Tuesday, July 10, 2007

Smoothing the GRIB

The smoothing algorhythm mentioned in an earlier post can be adapted to the GRIB Data.
It allows you to turn this:

into that:

This smoothing is spatial, in other words, it fills the gap between the points.
This can reduce substantially the size of the GRIB data to download, as it gives the possibility to rebuild the data between the actual points. This will need some validation, but that sounds promising. SailMail users might be concerned; on the example above, the size of the GRIB file is ~15 times smaller.
The next step will be to add a time dimension, smoothing the wind across several frames.
Keep posted!

Tuesday, May 8, 2007

More projections, plus pattern concept

More projections are now supported in the Weather Assistant tool. Lambert is one of them, used by the Aussie's Bureau of Meteorology.
The image on the left illustrates that feature. It seems that the surface charts and the 500mb ones are using slightly different parameters (like contact parallel) for their charts. Anyway, that is useful to have this one supported.

Beside that, we now have the concept of pattern supported. It gives you the possibility to reuse the parameters of a composite for another one.
For example, you have created a composite for the North Pacific, with a surface chart, a 500mb one, with a chart on top of it. You can create a "pattern" out of it, and when you will "Load with Pattern..." from the menu, you will be prompted for the faxes, but all the size, position and scale parameters will remain the same. Makes the creation process for the composite much faster.

Next step will be the improvement of the satellite view, to be able to plot position on satellite images...

Monday, March 12, 2007

Smoothing GRIB Data

In order to minimize the size of the data that come back from the GRIB requests, I am working on some smoothing feature for the GRIB viewer. This intends to render a smoothed view of the GRIB files, even if the cells are bigger than 1 degree by 1 degree. This smoothing can also happen along the time dimension, from one GRIB layer to another, which would allow a better routing.
The idea is to determine the four closest GRIB points, and smooth the wind speed and direction, geographically, and along time, in case the GRIB has several frames, and you request the wind data between two frames. On the right is a first test of such a smoothing. The red are the GRIB data, the blue are calculated by the smoothing algorithm.

Tuesday, March 6, 2007

3D Grib files

Still making progresses on the weather charts program. Now we can visualize the GRIB files over the globe...
I'm still fighting with the Lambert projection..., we'll get there. The soft is almost good to be released, as - let's say - developer preview.
Print capabilities have been added too.
The superimposition of the faxes works well for the Mercator projection, and this is the most important for now. Surface analysis below a 500mb chart are really kicking asses. Quite a neat tool.

Wednesday, February 14, 2007

Weather Assistant Software almost ready to be released

The Weather Assistant software is coming good, almost ready to be released as version 0.9...
The documentation - at least a first drop of the user manual - is already available.
Find it here.
In conjunction with SailFax, this will really help to read all the data we are able to receive from the boat.

Monday, January 29, 2007

Plot the boat on Google Maps

Preparing a way to plot the boat's position from the email, on the blog.
Here is a sneak preview of what can be expected...

Thursday, January 25, 2007

SailFax, utility for SkedFile.txt

Almost done with SailFax. See a preview here.
Will soon be available for download.

Thursday, January 11, 2007

More Software to come

Working on several applications around AirMail & GetFax.
The first one is a Graphical User Interface for SkedFile.txt, the one that is used by the automatic feature of GetMail.
The second is a viewer that will be able to stack the faxes received by GetFax, and a chart, on which you can display your position, way points, grib files, etc.
In other words, it gives the possibility to override a fax, with accurate geographical data, like position. You know in Lat and Long where you are on the fax.