src/Environment/metarproperties.cxx

   1 // metarproperties.cxx -- Parse a METAR and write properties
   2 //
   3 // Written by David Megginson, started May 2002.
   4 // Rewritten by Torsten Dreyer, August 2010
   5 //
   6 // Copyright (C) 2002  David Megginson - david@megginson.com
   7 //
   8 // This program is free software; you can redistribute it and/or
   9 // modify it under the terms of the GNU General Public License as
  10 // published by the Free Software Foundation; either version 2 of the
  11 // License, or (at your option) any later version.
  12 //
  13 // This program is distributed in the hope that it will be useful, but
  14 // WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 // General Public License for more details.
  17 //
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  21 //
  22
  23 #ifdef HAVE_CONFIG_H
  24 #  include <config.h>
  25 #endif
  26
  27 #include "metarproperties.hxx"
  28 #include "fgmetar.hxx"
  29 #include "environment.hxx"
  30 #include "atmosphere.hxx"
  31 #include "metarairportfilter.hxx"
  32 #include <simgear/scene/sky/cloud.hxx>
  33 #include <simgear/structure/exception.hxx>
  34 #include <simgear/misc/strutils.hxx>
  35 #include <simgear/magvar/magvar.hxx>
  36 #include <simgear/timing/sg_time.hxx>
  37 #include <Main/fg_props.hxx>
  38
  39 using std::string;
  40
  41 namespace Environment {
  42
  43 static vector<string> coverage_string;
  44
  45 /**
  46  * @brief Helper class to wrap SGMagVar functionality and cache the variation and dip for
  47  *        a certain position.
  48  */
  49 class MagneticVariation : public SGMagVar {
  50 public:
  51   /**
  52    * Constructor
  53    */
  54   MagneticVariation() : _lat(1), _lon(1), _alt(1) {
  55     recalc( 0.0, 0.0, 0.0 );
  56   }
  57
  58   /**
  59    * @brief get the magnetic variation for a specific position at the current time
  60    * @param lon the positions longitude in degrees
  61    * @param lat the positions latitude in degrees
  62    * @param alt the positions height above MSL (aka altitude) in feet
  63    * @return the magnetic variation in degrees
  64    */
  65   double get_variation_deg( double lon, double lat, double alt );
  66
  67   /**
  68    * @brief get the magnetic dip for a specific position at the current time
  69    * @param lon the positions longitude in degrees
  70    * @param lat the positions latitude in degrees
  71    * @param alt the positions height above MSL (aka altitude) in feet
  72    * @return the magnetic dip in degrees
  73    */
  74   double get_dip_deg( double lon, double lat, double alt );
  75 private:
  76   void recalc( double lon, double lat, double alt );
  77   SGTime _time;
  78   double _lat, _lon, _alt;
  79 };
  80
  81 inline void MagneticVariation::recalc( double lon, double lat, double alt )
  82 {
  83   // calculation of magnetic variation is expensive. Cache the position
  84   // and perform this calculation only if it has changed
  85   if( _lon != lon || _lat != lat || _alt != alt ) {
  86     SG_LOG(SG_ALL, SG_DEBUG, "Recalculating magvar for lon=" << lon << ", lat=" << lat << ", alt=" << alt );
  87     _lon = lon;
  88     _lat = lat;
  89     _alt = alt;
  90
  91     lon *= SGD_DEGREES_TO_RADIANS;
  92     lat *= SGD_DEGREES_TO_RADIANS;
  93     alt *= SG_FEET_TO_METER;
  94    _time.update( lon, lat, 0, 0 );
  95     update( lon, lat, alt, _time.getJD() );
  96   }
  97 }
  98
  99 inline double MagneticVariation::get_variation_deg( double lon, double lat, double alt )
 100 {
 101   recalc( lon, lat, alt );
 102   return get_magvar() * SGD_RADIANS_TO_DEGREES;
 103 }
 104
 105 inline double MagneticVariation::get_dip_deg( double lon, double lat, double alt )
 106 {
 107   recalc( lon, lat, alt );
 108   return get_magdip() * SGD_RADIANS_TO_DEGREES;
 109 }
 110
 111 MetarProperties::MetarProperties( SGPropertyNode_ptr rootNode ) :
 112   _rootNode(rootNode),
 113   _metarValidNode( rootNode->getNode( "valid", true ) ),
 114   _station_elevation(0.0),
 115   _station_latitude(0.0),
 116   _station_longitude(0.0),
 117   _min_visibility(16000.0),
 118   _max_visibility(16000.0),
 119   _base_wind_dir(0),
 120   _base_wind_range_from(0),
 121   _base_wind_range_to(0),
 122   _wind_speed(0.0),
 123   _wind_from_north_fps(0.0),
 124   _wind_from_east_fps(0.0),
 125   _gusts(0.0),
 126   _temperature(0.0),
 127   _dewpoint(0.0),
 128   _humidity(0.0),
 129   _pressure(0.0),
 130   _sea_level_temperature(0.0),
 131   _sea_level_dewpoint(0.0),
 132   _sea_level_pressure(29.92),
 133   _rain(0.0),
 134   _hail(0.0),
 135   _snow(0.0),
 136   _snow_cover(false),
 137   _magneticVariation(new MagneticVariation())
 138 {
 139   // Hack to avoid static initialization order problems on OSX
 140   if( coverage_string.size() == 0 ) {
 141     coverage_string.push_back(SGCloudLayer::SG_CLOUD_CLEAR_STRING);
 142     coverage_string.push_back(SGCloudLayer::SG_CLOUD_FEW_STRING);
 143     coverage_string.push_back(SGCloudLayer::SG_CLOUD_SCATTERED_STRING);
 144     coverage_string.push_back(SGCloudLayer::SG_CLOUD_BROKEN_STRING);
 145     coverage_string.push_back(SGCloudLayer::SG_CLOUD_OVERCAST_STRING);
 146   }
 147   // don't tie metar-valid, so listeners get triggered
 148   _metarValidNode->setBoolValue( false );
 149   _tiedProperties.setRoot( _rootNode );
 150   _tiedProperties.Tie("data", this, &MetarProperties::get_metar, &MetarProperties::set_metar );
 151   _tiedProperties.Tie("station-id", this, &MetarProperties::get_station_id, &MetarProperties::set_station_id );
 152   _tiedProperties.Tie("station-elevation-ft", &_station_elevation );
 153   _tiedProperties.Tie("station-latitude-deg", &_station_latitude );
 154   _tiedProperties.Tie("station-longitude-deg", &_station_longitude );
 155   _tiedProperties.Tie("station-magnetic-variation-deg", this, &MetarProperties::get_magnetic_variation_deg );
 156   _tiedProperties.Tie("station-magnetic-dip-deg", this, &MetarProperties::get_magnetic_dip_deg );
 157   _tiedProperties.Tie("min-visibility-m", &_min_visibility );
 158   _tiedProperties.Tie("max-visibility-m", &_max_visibility );
 159   _tiedProperties.Tie("base-wind-range-from", &_base_wind_range_from );
 160   _tiedProperties.Tie("base-wind-range-to", &_base_wind_range_to );
 161   _tiedProperties.Tie("base-wind-speed-kt", this, &MetarProperties::get_wind_speed, &MetarProperties::set_wind_speed );
 162   _tiedProperties.Tie("base-wind-dir-deg", this, &MetarProperties::get_base_wind_dir, &MetarProperties::set_base_wind_dir );
 163   _tiedProperties.Tie("base-wind-from-north-fps", this, &MetarProperties::get_wind_from_north_fps, &MetarProperties::set_wind_from_north_fps );
 164   _tiedProperties.Tie("base-wind-from-east-fps",this, &MetarProperties::get_wind_from_east_fps, &MetarProperties::set_wind_from_east_fps );
 165   _tiedProperties.Tie("gust-wind-speed-kt", &_gusts );
 166   _tiedProperties.Tie("temperature-degc", &_temperature );
 167   _tiedProperties.Tie("dewpoint-degc", &_dewpoint );
 168   _tiedProperties.Tie("rel-humidity-norm", &_humidity );
 169   _tiedProperties.Tie("pressure-inhg", &_pressure );
 170   _tiedProperties.Tie("temperature-sea-level-degc", &_sea_level_temperature );
 171   _tiedProperties.Tie("dewpoint-sea-level-degc", &_sea_level_dewpoint );
 172   _tiedProperties.Tie("pressure-sea-level-inhg", &_sea_level_pressure );
 173   _tiedProperties.Tie("rain-norm", &_rain );
 174   _tiedProperties.Tie("hail-norm", &_hail );
 175   _tiedProperties.Tie("snow-norm", &_snow);
 176   _tiedProperties.Tie("snow-cover", &_snow_cover );
 177   _tiedProperties.Tie("decoded", this, &MetarProperties::get_decoded );
 178 }
 179
 180 MetarProperties::~MetarProperties()
 181 {
 182   delete _magneticVariation;
 183 }
 184
 185
 186 static const double thickness_value[] = { 0, 65, 600, 750, 1000 };
 187
 188 void MetarProperties::set_metar( const char * metar )
 189 {
 190     _metar = metar;
 191
 192     SGSharedPtr<FGMetar> m;
 193     try {
 194         m = new FGMetar( _metar );
 195     }
 196     catch( sg_io_exception ) {
 197         SG_LOG( SG_GENERAL, SG_WARN, "Can't parse metar: " << _metar );
 198         _metarValidNode->setBoolValue(false);
 199         return;
 200     }
 201
 202     _decoded.clear();
 203     const vector<string> weather = m->getWeather();
 204     for( vector<string>::const_iterator it = weather.begin(); it != weather.end(); it++ ) {
 205         if( false == _decoded.empty() ) _decoded.append(", ");
 206         _decoded.append(*it);
 207     }
 208
 209     _min_visibility = m->getMinVisibility().getVisibility_m();
 210     _max_visibility = m->getMaxVisibility().getVisibility_m();
 211
 212     const SGMetarVisibility *dirvis = m->getDirVisibility();
 213     for ( int i = 0; i < 8; i++, dirvis++) {
 214         SGPropertyNode *vis = _rootNode->getChild("visibility", i, true);
 215         double v = dirvis->getVisibility_m();
 216
 217         vis->setDoubleValue("min-m", v);
 218         vis->setDoubleValue("max-m", v);
 219     }
 220
 221     set_base_wind_dir(m->getWindDir());
 222     _base_wind_range_from = m->getWindRangeFrom();
 223     _base_wind_range_to = m->getWindRangeTo();
 224     set_wind_speed(m->getWindSpeed_kt());
 225
 226     _gusts = m->getGustSpeed_kt();
 227     _temperature = m->getTemperature_C();
 228     _dewpoint = m->getDewpoint_C();
 229     _humidity = m->getRelHumidity();
 230     _pressure = m->getPressure_inHg();
 231
 232     {
 233         // 1. check the id given in the metar
 234         FGAirport* a = FGAirport::findByIdent(m->getId());
 235
 236         // 2. if unknown, find closest airport with metar to current position
 237         if( a == NULL ) {
 238             SGGeod pos = SGGeod::fromDeg(
 239                 fgGetDouble( "/position/longitude-deg", 0.0 ),
 240                 fgGetDouble( "/position/latitude-deg", 0.0 ) );
 241             a = FGAirport::findClosest(pos, 10000.0, MetarAirportFilter::instance() );
 242         }
 243
 244         // 3. otherwise use ground elevation
 245         if( a != NULL ) {
 246             _station_elevation = a->getElevation();
 247             const SGGeod & towerPosition = a->getTowerLocation();
 248             _station_latitude = towerPosition.getLatitudeDeg();
 249             _station_longitude = towerPosition.getLongitudeDeg();
 250             _station_id = a->ident();
 251         } else {
 252             _station_elevation = fgGetDouble("/position/ground-elev-m", 0.0 ) * SG_METER_TO_FEET;
 253             _station_latitude = fgGetDouble( "/position/latitude-deg", 0.0 );
 254             _station_longitude = fgGetDouble( "/position/longitude-deg", 0.0 );
 255             _station_id = "XXXX";
 256         }
 257     }
 258
 259     {    // calculate sea level temperature, dewpoint and pressure
 260         FGEnvironment dummy; // instantiate a dummy so we can leech a method
 261         dummy.set_elevation_ft( _station_elevation );
 262         dummy.set_temperature_degc( _temperature );
 263         dummy.set_dewpoint_degc( _dewpoint );
 264         _sea_level_temperature = dummy.get_temperature_sea_level_degc();
 265         _sea_level_dewpoint = dummy.get_dewpoint_sea_level_degc();
 266
 267         double elevation_m = _station_elevation * SG_FEET_TO_METER;
 268         double fieldPressure = FGAtmo::fieldPressure( elevation_m, _pressure * atmodel::inHg );
 269         _sea_level_pressure = P_layer(0, elevation_m, fieldPressure, _temperature + atmodel::freezing, atmodel::ISA::lam0) / atmodel::inHg;
 270     }
 271
 272     bool isBC = false;
 273     bool isBR = false;
 274     bool isFG = false;
 275     bool isMI = false;
 276     bool isHZ = false;
 277
 278     {
 279         for( unsigned i = 0; i < 3; i++ ) {
 280             SGPropertyNode_ptr n = _rootNode->getChild("weather", i, true );
 281             vector<struct SGMetar::Weather> weather = m->getWeather2();
 282             struct SGMetar::Weather * w = i < weather.size() ? &weather[i] : NULL;
 283             n->getNode("intensity",true)->setIntValue( w != NULL ? w->intensity : 0 );
 284             n->getNode("vincinity",true)->setBoolValue( w != NULL ? w->vincinity : false );
 285             for( unsigned j = 0; j < 3; j++ ) {
 286
 287                 const string & phenomenon = w != NULL && j < w->phenomena.size() ? w->phenomena[j].c_str() : "";
 288                 n->getChild( "phenomenon", j, true )->setStringValue( phenomenon );
 289
 290                 const string & description = w != NULL && j < w->descriptions.size() ? w->descriptions[j].c_str() : "";
 291                 n->getChild( "description", j, true )->setStringValue( description );
 292
 293                 // need to know later,
 294                 // if its fog(FG) (might be shallow(MI) or patches(BC)) or haze (HZ) or mist(BR)
 295                 if( phenomenon == "FG" ) isFG = true;
 296                 if( phenomenon == "HZ" ) isHZ = true;
 297                 if( phenomenon == "BR" ) isBR = true;
 298                 if( description == "MI" ) isMI = true;
 299                 if( description == "BC" ) isBC = true;
 300             }
 301         }
 302     }
 303
 304     {
 305         static const char * LAYER = "layer";
 306         SGPropertyNode_ptr cloudsNode = _rootNode->getNode("clouds", true );
 307         const vector<SGMetarCloud> & metarClouds = m->getClouds();
 308         unsigned layerOffset = 0; // Oh, this is ugly!
 309
 310         // fog/mist/haze cloud layer does not work with 3d clouds yet :-(
 311         bool setGroundCloudLayer = _rootNode->getBoolValue("set-ground-cloud-layer", false ) &&
 312               false == (fgGetBool("/sim/rendering/shader-effects", false ) &&
 313                         fgGetBool("/sim/rendering/clouds3d-enable", false ) );
 314
 315         if( setGroundCloudLayer ) {
 316             // create a cloud layer #0 starting at the ground if its fog, mist or haze
 317
 318             // make sure layer actually starts at ground and set it's bottom at a constant
 319             // value below the station's elevation
 320             const double LAYER_BOTTOM_STATION_OFFSET =
 321               fgGetDouble( "/environment/params/fog-mist-haze-layer/offset-from-station-elevation-ft", -200 );
 322
 323             SGMetarCloud::Coverage coverage = SGMetarCloud::COVERAGE_NIL;
 324             double thickness = 0;
 325             double alpha = 1.0;
 326
 327             if( isFG ) { // fog
 328                 coverage = SGMetarCloud::getCoverage( isBC ?
 329                     fgGetString( "/environment/params/fog-mist-haze-layer/fog-bc-2dlayer-coverage", SGMetarCloud::COVERAGE_SCATTERED_STRING ) :
 330                     fgGetString( "/environment/params/fog-mist-haze-layer/fog-2dlayer-coverage", SGMetarCloud::COVERAGE_BROKEN_STRING )
 331                 );
 332
 333                 thickness = isMI ?
 334                    fgGetDouble("/environment/params/fog-mist-haze-layer/fog-shallow-thickness-ft",30) - LAYER_BOTTOM_STATION_OFFSET : // shallow fog, 10m/30ft
 335                    fgGetDouble("/environment/params/fog-mist-haze-layer/fog-thickness-ft",500) - LAYER_BOTTOM_STATION_OFFSET; // fog, 150m/500ft
 336                 alpha =  fgGetDouble("/environment/params/fog-mist-haze-layer/fog-2dlayer-alpha", 1.0);
 337             } else if( isBR ) { // mist
 338                 coverage = SGMetarCloud::getCoverage(fgGetString("/environment/params/fog-mist-haze-layer/mist-2dlayer-coverage", SGMetarCloud::COVERAGE_OVERCAST_STRING));
 339                 thickness =  fgGetDouble("/environment/params/fog-mist-haze-layer/mist-thickness-ft",2000) - LAYER_BOTTOM_STATION_OFFSET;
 340                 alpha =  fgGetDouble("/environment/params/fog-mist-haze-layer/mist-2dlayer-alpha",0.8);
 341             } else if( isHZ ) { // haze
 342                 coverage = SGMetarCloud::getCoverage(fgGetString("/environment/params/fog-mist-haze-layer/mist-2dlayer-coverage", SGMetarCloud::COVERAGE_OVERCAST_STRING));
 343                 thickness =  fgGetDouble("/environment/params/fog-mist-haze-layer/haze-thickness-ft",2000) - LAYER_BOTTOM_STATION_OFFSET;
 344                 alpha =  fgGetDouble("/environment/params/fog-mist-haze-layer/haze-2dlayer-alpha",0.6);
 345             }
 346
 347             if( coverage != SGMetarCloud::COVERAGE_NIL ) {
 348
 349                 // if there is a layer above the fog, limit the top to one foot below that layer's bottom
 350                 if( metarClouds.size() > 0 && metarClouds[0].getCoverage() != SGMetarCloud::COVERAGE_CLEAR )
 351                     thickness = metarClouds[0].getAltitude_ft() - LAYER_BOTTOM_STATION_OFFSET - 1;
 352
 353                 SGPropertyNode_ptr layerNode = cloudsNode->getChild(LAYER, 0, true );
 354                 layerNode->setDoubleValue( "coverage-type", SGCloudLayer::getCoverageType(coverage_string[coverage]) );
 355                 layerNode->setStringValue( "coverage", coverage_string[coverage] );
 356                 layerNode->setDoubleValue( "elevation-ft", _station_elevation + LAYER_BOTTOM_STATION_OFFSET );
 357                 layerNode->setDoubleValue( "thickness-ft", thickness );
 358                 layerNode->setDoubleValue( "visibility-m", _min_visibility );
 359                 layerNode->setDoubleValue( "alpha", alpha );
 360                 _min_visibility = _max_visibility =
 361                   fgGetDouble("/environment/params/fog-mist-haze-layer/visibility-above-layer-m",20000.0); // assume good visibility above the fog
 362                 layerOffset = 1;  // shudder
 363             }
 364         }
 365
 366         for( unsigned i = 0; i < 5-layerOffset; i++ ) {
 367             SGPropertyNode_ptr layerNode = cloudsNode->getChild(LAYER, i+layerOffset, true );
 368             SGMetarCloud::Coverage coverage = i < metarClouds.size() ? metarClouds[i].getCoverage() : SGMetarCloud::COVERAGE_CLEAR;
 369             double elevation =
 370                 i >= metarClouds.size() || coverage == SGMetarCloud::COVERAGE_CLEAR ?
 371                 -9999.0 :
 372                 metarClouds[i].getAltitude_ft() + _station_elevation;
 373
 374             layerNode->setDoubleValue( "alpha", 1.0 );
 375             layerNode->setStringValue( "coverage", coverage_string[coverage] );
 376             layerNode->setDoubleValue( "coverage-type", SGCloudLayer::getCoverageType(coverage_string[coverage]) );
 377             layerNode->setDoubleValue( "elevation-ft", elevation );
 378             layerNode->setDoubleValue( "thickness-ft", thickness_value[coverage]);
 379             layerNode->setDoubleValue( "span-m", 40000 );
 380             layerNode->setDoubleValue( "visibility-m", 50.0 );
 381         }
 382     }
 383
 384     _rain = m->getRain();
 385     _hail = m->getHail();
 386     _snow = m->getSnow();
 387     _snow_cover = m->getSnowCover();
 388     _metarValidNode->setBoolValue(true);
 389 }
 390
 391 void MetarProperties::setStationId( const std::string & value )
 392 {
 393     set_station_id(simgear::strutils::strip(value).c_str());
 394 }
 395
 396 double MetarProperties::get_magnetic_variation_deg() const
 397 {
 398   return _magneticVariation->get_variation_deg( _station_longitude, _station_latitude, _station_elevation );
 399 }
 400
 401 double MetarProperties::get_magnetic_dip_deg() const
 402 {
 403   return _magneticVariation->get_dip_deg( _station_longitude, _station_latitude, _station_elevation );
 404 }
 405
 406 static inline void calc_wind_hs( double north_fps, double east_fps, int & heading_deg, double & speed_kt )
 407 {
 408     speed_kt = sqrt((north_fps)*(north_fps)+(east_fps)*(east_fps)) * 3600.0 / (SG_NM_TO_METER * SG_METER_TO_FEET);
 409     heading_deg = SGMiscd::roundToInt(
 410         SGMiscd::normalizeAngle2( atan2( east_fps, north_fps ) ) * SGD_RADIANS_TO_DEGREES );
 411 }
 412
 413 void MetarProperties::set_wind_from_north_fps( double value )
 414 {
 415     _wind_from_north_fps = value;
 416     calc_wind_hs( _wind_from_north_fps, _wind_from_east_fps, _base_wind_dir, _wind_speed );
 417 }
 418
 419 void MetarProperties::set_wind_from_east_fps( double value )
 420 {
 421     _wind_from_east_fps = value;
 422     calc_wind_hs( _wind_from_north_fps, _wind_from_east_fps, _base_wind_dir, _wind_speed );
 423 }
 424
 425 static inline void calc_wind_ne( double heading_deg, double speed_kt, double & north_fps, double & east_fps )
 426 {
 427     double speed_fps = speed_kt * SG_NM_TO_METER * SG_METER_TO_FEET / 3600.0;
 428     north_fps = speed_fps * cos(heading_deg * SGD_DEGREES_TO_RADIANS);
 429     east_fps = speed_fps * sin(heading_deg * SGD_DEGREES_TO_RADIANS);
 430 }
 431
 432 void MetarProperties::set_base_wind_dir( double value )
 433 {
 434     _base_wind_dir = value;
 435     calc_wind_ne( (double)_base_wind_dir, _wind_speed, _wind_from_north_fps, _wind_from_east_fps );
 436 }
 437
 438 void MetarProperties::set_wind_speed( double value )
 439 {
 440     _wind_speed = value;
 441     calc_wind_ne( (double)_base_wind_dir, _wind_speed, _wind_from_north_fps, _wind_from_east_fps );
 442 }
 443
 444
 445 } // namespace Environment