Difference between revisions of "DataFiles"

Revision as of 07:00, 9 October 2014

VRtool needs data to perform calculations. Those have to be loaded in the program before you can use the track designer or the weather routing module, for example. These data files are charts, wind forecasts and polars. All VRTool data files are in text format, to allow easy editing and repairing files.

Charts

Vrtool uses a custom vector chart format files, with extension .CHT. The program comes with a simple world map (world3.cht). You can find more detailed files in vrtoutoulz or in the chart lib. Download and save the chart file to the vrtool program folder (p.e. c:\program files\vrtool). To load a chart, use menu option File > Open Vector Chart...

Tip: A good world chart is c_gshhs_i.cht (from vrtoutoulz [1] ). It was ported by Ricoo to vrtool format from the 
Global Self-consistent, Hierarchical, High-resolution Shoreline Database [2].

Wind forecasts

These can be obtained from a number of sources. Ultimately, all wind forecasts come from the GFS ( Global Forecast System, a world weather model updated NOAA every six hours), but regatta game providers do some processing in NOAA data. VRTool can use winds from:

• Downloaded directly from the NOAA server using the vrtool's built-in NOAA import module. This method gives the earliest possible forecast updates, as the NOAA server is also the source for the other methods. This is also the most convenient way to import a grib covering the whole area of a race leg. Once the grib boundaries have been set in the NOAA import module, vrtool remembers them for subesquent imports. This makes subsequent updating of the wind grid a one-click process.
• From vrtoutoulz website - Set regatta server host to www.vrtoutoulz.fr/winds, point any location with the mouse and press F2. This will load a 10x10 degree wind grid.
• Load a GRIB2 format file ( p.e. files downloaded by UGrib or ZGrib ).
• If you use the Firefox browser you can extract Virtual Regatta game winds from the browser cache using the Firefox cache importer built into VRTool. (This "back-door" method depends on both the game file format and the browser cache management - it may stop working unexpectedly if either of these changes). Read more about this method in this tutorial.

After loading the wind forecasts you may use buttons to select a given forecast. Use buttons Ctrl-1 to Ctrl-7 or the buttons in the toolbar to display successive wind forecast periods.

Polars

Polars allow the calculation of the boat speed for a given wind speed and wind angle.

Vrtool can use two kinds of polar chart databases.

• Multi-sail polars - This is a new format with a set of polar data for each sail. This is the preferred format. Multi-sail polar database files have extension XML, and can be produced, imported and edited using the vrtool polar studio.
• Merged sail polars - This compact polar database format is available from sources like vrtoutoulz [3] . Extension .CSV.

Select the file and click load. Also select which database type you are using in the Winds > Polars tab.

Importing boat data

VRTool can import boat data from the following sources:

• From an NMEA stream on a TCP/IP network on on-board wired or wireless network. VRTool can interpret and plot the position of your boat (using NMEA GPS messages) and nearby boats (using AIS messages).
• For games, the same data can be imported over the internet via TCP/IP proxy server. The positions of your game friend's boats can also be imported and plotted if the proxy feeds these as NMEA AIS messages.
• From an on-board NMEA network through a hard-wired COM port.
• For Virtual Regatta games: VRTool can be configured to poll the game server directly to retrieve the position, course and speed of your boat and your friends.
• For Virtual Regatta games: VRTool can recover boat positions (and game weather) from Firefox browser cache if you are running the game console in Firefox.