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NauticalMan14 05-02-2013 17:31

WeatherFax ...
Where can I find out how to view synoptic charts from NOAA within OpenCPN?

nohal 05-02-2013 20:41

Re: WeatherFax...
Read about own chart calibration in the manual. A bit techie though. So far the easiest way to create your own charts from whatever imagery is to use GE2KAP (if you are using Windows) - The thread is long, but you will find an answer to pretty much any question you could have about it. And will probably be interesting for you...


jackdale 05-02-2013 23:01

Re: WeatherFax...
Why would you want to read a weather fax in OpenCPN?

nohal 05-02-2013 23:12

Re: WeatherFax...
To see a meteorologist's opinion about the weather to come? I'm myself pretty happy with the gribs most of the time, but can understand that there are people who aren't, or just want to see what those guys being paid for it think. Having it displayed in the place where it belongs on the globe is just a convenience bonus which is actually not that hard to get.

jackdale 05-02-2013 23:14

Re: WeatherFax...
There are programs designed specifically for viewing weather faxes. I know what they are; I use them myself.

Another thread

nohal 05-02-2013 23:20

Re: WeatherFax...
Yes, there are. I use them too when I want to. Or I calibrate the pictures to view them in OpenCPN if I feel like I want to - takes seconds once you have the calibration for the zone of interest done once and the scripts written. Both is cool and useful and a matter of personal preference and current need.

Dockhead 06-02-2013 00:26

Re: WeatherFax...
Gribs and Weatherfax perform very different functions. Grib files give you wind predictions which pretty much any sailor can use without interpretation for wind, generally short term (more than three days out they don't tend to be very accurate). Weatherfax gives you synoptic charts for predicting weather altogether. You need some training and study in weather to be able to use them.

rgleason 06-02-2013 06:41

Re: WeatherFax...
In qtVlm you can set up Noaa weatherfax (location and scale) and after trying it once or twice, I believe it would be pretty useful because would make the information available in the primary tool, OpenCpn and more convenient. I think Nautical Man's question is a good on. I am going to have to try what Nohal suggests, and I agree with what he says too about convenience.

Overlay In qtVlm, pretty funny events afterward. Missed the finish!

dougwm10 06-02-2013 14:10

Re: WeatherFax...
Would it not be possible to produce a PLUG-IN that enables weather-faxes to be shown directly on the charts in OpenCPN in a similar way that GRIB files are able to be shown.

The advantages for passage making are to my mind compelling since weather-faxes give world wide coverage and can be received anywhere through a standard SSB receiver with no additional equipment or membership requirements and connection costs i.e. Satellite or SailMail.

Receiving Gribs when on passage requires either a SATELLITE connection or a PACTOR MODEM attached to the SSB together with an annual subscription to the sending service. Both of these options are very expensive and require additional receiving equipment which adds to the complexities and is yet another item that can fail.

Surely we should be following the KISS rule – keep it as simple as possible and keep the equipment used as minimal as possible.

Does anyone know if a weather-fax viewer can be designed and incorporated as a Plug-in to OPCN ????

sailorF54 06-02-2013 14:27

Re: WeatherFax...
I see no reason why a Weather fax pluging should be impossible to design. And I second Dougwn10's proposal.
(Unfortunately my programming skills are too rusty...)

jackdale 06-02-2013 15:23

Re: WeatherFax...
For those who want to understand how to read weather fax

boat_alexandra 07-02-2013 01:45

Re: WeatherFax...
I wrote yahfax (on sourceforge) while crossing the pacific, which is a fast opensource weather fax program.

I'm currently working on enhancing wmm and grib plugins.. I could use some testing on those:

I could write this plugin, I have it planned along with about 5 other plugins that I haven't started. A few things:

1. I only use linux. Can someone here who uses windows and can compile and test opencpn on windows with a SSB agree to do some testing?
2. How does it know where to put the weather fax? Should the user drag and drop it or something? Same for scaling?
3. wxWidgets does not support recording audio. What library should be used? Is it ok to only support reading wav files from disk at least at first?

rgleason 07-02-2013 05:33

Re: WeatherFax...
boat_alexandra that would be WONDERFUL.

1. I use Win7 can compile and test Opencpn and plugins, but I don't have an SSB. However a friend does and it will be available after the covers come off this spring. Will that be too late? I'd like to help.

2. qtVlm allows us to select the location by browsing the file structure. You can see the directory in the link below. Once a given fax series is setup, those settings can remain. qtVlm has a number of setups that can be used to save the settings.

I'll tell you how the Routing Software qtVlm locates and scales the weather fax, at first it was a little awkward, but it was actually self explanatory and quite easy.

First take a look at this snapshot with the input area to locate and scale the fax in qtVlm

I can attach some other shots of the process.

In qtVlm you select
Gribfile > Open Fax Meteo (or Close Fax Meteo)
A window pops up if you select Open Fax Meteo
The popup contains:
"Fax file's name" "C:/Data-Dart/Grib/Image01.gif" with "Browse" button
"Left corner position"
Latitude North/South dropdown, Degree selection, decimal minutes
Longitude West/East dropdown, Degree selection, decimal minutes
Longitude: 120 degrees for example
Latitude 50 degrees for example
Simple slider
"Preset Number"
qtVlm has 4 selections for setups. It would probably be good to have a few more.

There is a note: Yoou can also use the mouse to move (SHIFT key), to resize (CTRL key), or to tuen opacity (ALT key)

3. wxWidgets does not support recording audio. What library should be used? Is it ok to only support reading wav files from disk at least at first?

--Ok this is about the source weatherfax file. I think you must be referring to Navtex weather fax and that must be a wav file which is picked up via SSB.
nohal or Dave or one of the other great programmers for OpenCpn will be able to help us with this question. (no disrespect for your skills intended!!!) --Grib file pluggin..wmm plugins. h'mm! -So much to learn for me.

What I did while using qtVlm from the desk with internet was simply download the weather fax off Noaa's website selecting the "product" desired. Ocean Prediction Center - Product Loops

cagney 07-02-2013 11:21

Re: WeatherFax...
1 Attachment(s)
A few samples of wx-fax-kaps.
Attachment 54165


jackdale 07-02-2013 11:27

Re: WeatherFax...

Originally Posted by cagney (Post 1150529)
A few samples of wx-fax-kaps.
Attachment 54165


I cannot open that file. Is it a pdf?

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