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_ENVIRONMENT, SG_DEBUG, "Recalculating magvar for lon=" << lon << ", lat=" << lat << ", alt=" << alt );
  87     _lon = lon;
  88     _lat = lat;
  89     _alt = alt;
  90
  91     SGGeod location(SGGeod::fromDegFt(lon, lat, alt));
  92    _time.update( location, 0, 0 );
  93     update( lon, lat, alt, _time.getJD() );
  94   }
  95 }
  96
  97 inline double MagneticVariation::get_variation_deg( double lon, double lat, double alt )
  98 {
  99   recalc( lon, lat, alt );
 100   return get_magvar() * SGD_RADIANS_TO_DEGREES;
 101 }
 102
 103 inline double MagneticVariation::get_dip_deg( double lon, double lat, double alt )
 104 {
 105   recalc( lon, lat, alt );
 106   return get_magdip() * SGD_RADIANS_TO_DEGREES;
 107 }
 108
 109 MetarProperties::MetarProperties( SGPropertyNode_ptr rootNode ) :
 110   _rootNode(rootNode),
 111   _metarValidNode( rootNode->getNode( "valid", true ) ),
 112   _station_elevation(0.0),
 113   _station_latitude(0.0),
 114   _station_longitude(0.0),
 115   _min_visibility(16000.0),
 116   _max_visibility(16000.0),
 117   _base_wind_dir(0),
 118   _base_wind_range_from(0),
 119   _base_wind_range_to(0),
 120   _wind_speed(0.0),
 121   _wind_from_north_fps(0.0),
 122   _wind_from_east_fps(0.0),
 123   _gusts(0.0),
 124   _temperature(0.0),
 125   _dewpoint(0.0),
 126   _humidity(0.0),
 127   _pressure(0.0),
 128   _sea_level_temperature(0.0),
 129   _sea_level_dewpoint(0.0),
 130   _sea_level_pressure(29.92),
 131   _rain(0.0),
 132   _hail(0.0),
 133   _snow(0.0),
 134   _snow_cover(false),
 135   _magneticVariation(new MagneticVariation())
 136 {
 137   // Hack to avoid static initialization order problems on OSX
 138   if( coverage_string.empty() ) {
 139     coverage_string.push_back(SGCloudLayer::SG_CLOUD_CLEAR_STRING);
 140     coverage_string.push_back(SGCloudLayer::SG_CLOUD_FEW_STRING);
 141     coverage_string.push_back(SGCloudLayer::SG_CLOUD_SCATTERED_STRING);
 142     coverage_string.push_back(SGCloudLayer::SG_CLOUD_BROKEN_STRING);
 143     coverage_string.push_back(SGCloudLayer::SG_CLOUD_OVERCAST_STRING);
 144   }
 145   // don't tie metar-valid, so listeners get triggered
 146   _metarValidNode->setBoolValue( false );
 147   _tiedProperties.setRoot( _rootNode );
 148   _tiedProperties.Tie("data", this, &MetarProperties::get_metar, &MetarProperties::set_metar );
 149   _tiedProperties.Tie("station-id", this, &MetarProperties::get_station_id, &MetarProperties::set_station_id );
 150   _tiedProperties.Tie("station-elevation-ft", &_station_elevation );
 151   _tiedProperties.Tie("station-latitude-deg", &_station_latitude );
 152   _tiedProperties.Tie("station-longitude-deg", &_station_longitude );
 153   _tiedProperties.Tie("station-magnetic-variation-deg", this, &MetarProperties::get_magnetic_variation_deg );
 154   _tiedProperties.Tie("station-magnetic-dip-deg", this, &MetarProperties::get_magnetic_dip_deg );
 155   _tiedProperties.Tie("min-visibility-m", &_min_visibility );
 156   _tiedProperties.Tie("max-visibility-m", &_max_visibility );
 157   _tiedProperties.Tie("base-wind-range-from", &_base_wind_range_from );
 158   _tiedProperties.Tie("base-wind-range-to", &_base_wind_range_to );
 159   _tiedProperties.Tie("base-wind-speed-kt", this, &MetarProperties::get_wind_speed, &MetarProperties::set_wind_speed );
 160   _tiedProperties.Tie("base-wind-dir-deg", this, &MetarProperties::get_base_wind_dir, &MetarProperties::set_base_wind_dir );
 161   _tiedProperties.Tie("base-wind-from-north-fps", this, &MetarProperties::get_wind_from_north_fps, &MetarProperties::set_wind_from_north_fps );
 162   _tiedProperties.Tie("base-wind-from-east-fps",this, &MetarProperties::get_wind_from_east_fps, &MetarProperties::set_wind_from_east_fps );
 163   _tiedProperties.Tie("gust-wind-speed-kt", &_gusts );
 164   _tiedProperties.Tie("temperature-degc", &_temperature );
 165   _tiedProperties.Tie("dewpoint-degc", &_dewpoint );
 166   _tiedProperties.Tie("rel-humidity-norm", &_humidity );
 167   _tiedProperties.Tie("pressure-inhg", &_pressure );
 168   _tiedProperties.Tie("temperature-sea-level-degc", &_sea_level_temperature );
 169   _tiedProperties.Tie("dewpoint-sea-level-degc", &_sea_level_dewpoint );
 170   _tiedProperties.Tie("pressure-sea-level-inhg", &_sea_level_pressure );
 171   _tiedProperties.Tie("rain-norm", &_rain );
 172   _tiedProperties.Tie("hail-norm", &_hail );
 173   _tiedProperties.Tie("snow-norm", &_snow);
 174   _tiedProperties.Tie("snow-cover", &_snow_cover );
 175   _tiedProperties.Tie("decoded", this, &MetarProperties::get_decoded );
 176 }
 177
 178 MetarProperties::~MetarProperties()
 179 {
 180   delete _magneticVariation;
 181 }
 182
 183
 184 static const double thickness_value[] = { 0, 65, 600, 750, 1000 };
 185
 186 void MetarProperties::set_metar( const char * metar )
 187 {
 188     _metar = metar;
 189
 190     SGSharedPtr<FGMetar> m;
 191     try {
 192         m = new FGMetar( _metar );
 193     }
 194     catch( sg_io_exception ) {
 195         SG_LOG( SG_ENVIRONMENT, SG_WARN, "Can't parse metar: " << _metar );
 196         _metarValidNode->setBoolValue(false);
 197         return;
 198     }
 199
 200     _decoded.clear();
 201     const vector<string> weather = m->getWeather();
 202     for( vector<string>::const_iterator it = weather.begin(); it != weather.end(); ++it ) {
 203         if( false == _decoded.empty() ) _decoded.append(", ");
 204         _decoded.append(*it);
 205     }
 206
 207     _min_visibility = m->getMinVisibility().getVisibility_m();
 208     _max_visibility = m->getMaxVisibility().getVisibility_m();
 209
 210     const SGMetarVisibility *dirvis = m->getDirVisibility();
 211     for ( int i = 0; i < 8; i++, dirvis++) {
 212         SGPropertyNode *vis = _rootNode->getChild("visibility", i, true);
 213         double v = dirvis->getVisibility_m();
 214
 215         vis->setDoubleValue("min-m", v);
 216         vis->setDoubleValue("max-m", v);
 217     }
 218
 219     set_base_wind_dir(m->getWindDir());
 220     _base_wind_range_from = m->getWindRangeFrom();
 221     _base_wind_range_to = m->getWindRangeTo();
 222     set_wind_speed(m->getWindSpeed_kt());
 223
 224     _gusts = m->getGustSpeed_kt();
 225     _temperature = m->getTemperature_C();
 226     _dewpoint = m->getDewpoint_C();
 227     _humidity = m->getRelHumidity();
 228     _pressure = m->getPressure_inHg();
 229
 230     {
 231         // 1. check the id given in the metar
 232         FGAirport* a = FGAirport::findByIdent(m->getId());
 233
 234         // 2. if unknown, find closest airport with metar to current position
 235         if( a == NULL ) {
 236             SGGeod pos = SGGeod::fromDeg(
 237                 fgGetDouble( "/position/longitude-deg", 0.0 ),
 238                 fgGetDouble( "/position/latitude-deg", 0.0 ) );
 239             a = FGAirport::findClosest(pos, 10000.0, MetarAirportFilter::instance() );
 240         }
 241
 242         // 3. otherwise use ground elevation
 243         if( a != NULL ) {
 244             _station_elevation = a->getElevation();
 245             const SGGeod & towerPosition = a->getTowerLocation();
 246             _station_latitude = towerPosition.getLatitudeDeg();
 247             _station_longitude = towerPosition.getLongitudeDeg();
 248             _station_id = a->ident();
 249         } else {
 250             _station_elevation = fgGetDouble("/position/ground-elev-m", 0.0 ) * SG_METER_TO_FEET;
 251             _station_latitude = fgGetDouble( "/position/latitude-deg", 0.0 );
 252             _station_longitude = fgGetDouble( "/position/longitude-deg", 0.0 );
 253             _station_id = "XXXX";
 254         }
 255     }
 256
 257     {    // calculate sea level temperature, dewpoint and pressure
 258         FGEnvironment dummy; // instantiate a dummy so we can leech a method
 259         dummy.set_elevation_ft( _station_elevation );
 260         dummy.set_temperature_degc( _temperature );
 261         dummy.set_dewpoint_degc( _dewpoint );
 262         _sea_level_temperature = dummy.get_temperature_sea_level_degc();
 263         _sea_level_dewpoint = dummy.get_dewpoint_sea_level_degc();
 264
 265         double elevation_m = _station_elevation * SG_FEET_TO_METER;
 266         double fieldPressure = FGAtmo::fieldPressure( elevation_m, _pressure * atmodel::inHg );
 267         _sea_level_pressure = P_layer(0, elevation_m, fieldPressure, _temperature + atmodel::freezing, atmodel::ISA::lam0) / atmodel::inHg;
 268     }
 269
 270     bool isBC = false;
 271     bool isBR = false;
 272     bool isFG = false;
 273     bool isMI = false;
 274     bool isHZ = false;
 275
 276     {
 277         for( unsigned i = 0; i < 3; i++ ) {
 278             SGPropertyNode_ptr n = _rootNode->getChild("weather", i, true );
 279             vector<struct SGMetar::Weather> weather = m->getWeather2();
 280             struct SGMetar::Weather * w = i < weather.size() ? &weather[i] : NULL;
 281             n->getNode("intensity",true)->setIntValue( w != NULL ? w->intensity : 0 );
 282             n->getNode("vincinity",true)->setBoolValue( w != NULL ? w->vincinity : false );
 283             for( unsigned j = 0; j < 3; j++ ) {
 284
 285                 const string & phenomenon = w != NULL && j < w->phenomena.size() ? w->phenomena[j].c_str() : "";
 286                 n->getChild( "phenomenon", j, true )->setStringValue( phenomenon );
 287
 288                 const string & description = w != NULL && j < w->descriptions.size() ? w->descriptions[j].c_str() : "";
 289                 n->getChild( "description", j, true )->setStringValue( description );
 290
 291                 // need to know later,
 292                 // if its fog(FG) (might be shallow(MI) or patches(BC)) or haze (HZ) or mist(BR)
 293                 if( phenomenon == "FG" ) isFG = true;
 294                 if( phenomenon == "HZ" ) isHZ = true;
 295                 if( phenomenon == "BR" ) isBR = true;
 296                 if( description == "MI" ) isMI = true;
 297                 if( description == "BC" ) isBC = true;
 298             }
 299         }
 300     }
 301
 302     {
 303         static const char * LAYER = "layer";
 304         SGPropertyNode_ptr cloudsNode = _rootNode->getNode("clouds", true );
 305         const vector<SGMetarCloud> & metarClouds = m->getClouds();
 306         unsigned layerOffset = 0; // Oh, this is ugly!
 307
 308         // fog/mist/haze cloud layer does not work with 3d clouds yet :-(
 309         bool setGroundCloudLayer = _rootNode->getBoolValue("set-ground-cloud-layer", false ) &&
 310               false == (fgGetBool("/sim/rendering/shader-effects", false ) &&
 311                         fgGetBool("/sim/rendering/clouds3d-enable", false ) );
 312
 313         if( setGroundCloudLayer ) {
 314             // create a cloud layer #0 starting at the ground if its fog, mist or haze
 315
 316             // make sure layer actually starts at ground and set it's bottom at a constant
 317             // value below the station's elevation
 318             const double LAYER_BOTTOM_STATION_OFFSET =
 319               fgGetDouble( "/environment/params/fog-mist-haze-layer/offset-from-station-elevation-ft", -200 );
 320
 321             SGMetarCloud::Coverage coverage = SGMetarCloud::COVERAGE_NIL;
 322             double thickness = 0;
 323             double alpha = 1.0;
 324
 325             if( isFG ) { // fog
 326                 coverage = SGMetarCloud::getCoverage( isBC ?
 327                     fgGetString( "/environment/params/fog-mist-haze-layer/fog-bc-2dlayer-coverage", SGMetarCloud::COVERAGE_SCATTERED_STRING ) :
 328                     fgGetString( "/environment/params/fog-mist-haze-layer/fog-2dlayer-coverage", SGMetarCloud::COVERAGE_BROKEN_STRING )
 329                 );
 330
 331                 thickness = isMI ?
 332                    fgGetDouble("/environment/params/fog-mist-haze-layer/fog-shallow-thickness-ft",30) - LAYER_BOTTOM_STATION_OFFSET : // shallow fog, 10m/30ft
 333                    fgGetDouble("/environment/params/fog-mist-haze-layer/fog-thickness-ft",500) - LAYER_BOTTOM_STATION_OFFSET; // fog, 150m/500ft
 334                 alpha =  fgGetDouble("/environment/params/fog-mist-haze-layer/fog-2dlayer-alpha", 1.0);
 335             } else if( isBR ) { // mist
 336                 coverage = SGMetarCloud::getCoverage(fgGetString("/environment/params/fog-mist-haze-layer/mist-2dlayer-coverage", SGMetarCloud::COVERAGE_OVERCAST_STRING));
 337                 thickness =  fgGetDouble("/environment/params/fog-mist-haze-layer/mist-thickness-ft",2000) - LAYER_BOTTOM_STATION_OFFSET;
 338                 alpha =  fgGetDouble("/environment/params/fog-mist-haze-layer/mist-2dlayer-alpha",0.8);
 339             } else if( isHZ ) { // haze
 340                 coverage = SGMetarCloud::getCoverage(fgGetString("/environment/params/fog-mist-haze-layer/mist-2dlayer-coverage", SGMetarCloud::COVERAGE_OVERCAST_STRING));
 341                 thickness =  fgGetDouble("/environment/params/fog-mist-haze-layer/haze-thickness-ft",2000) - LAYER_BOTTOM_STATION_OFFSET;
 342                 alpha =  fgGetDouble("/environment/params/fog-mist-haze-layer/haze-2dlayer-alpha",0.6);
 343             }
 344
 345             if( coverage != SGMetarCloud::COVERAGE_NIL ) {
 346
 347                 // if there is a layer above the fog, limit the top to one foot below that layer's bottom
 348                 if( metarClouds.size() > 0 && metarClouds[0].getCoverage() != SGMetarCloud::COVERAGE_CLEAR )
 349                     thickness = metarClouds[0].getAltitude_ft() - LAYER_BOTTOM_STATION_OFFSET - 1;
 350
 351                 SGPropertyNode_ptr layerNode = cloudsNode->getChild(LAYER, 0, true );
 352                 layerNode->setDoubleValue( "coverage-type", SGCloudLayer::getCoverageType(coverage_string[coverage]) );
 353                 layerNode->setStringValue( "coverage", coverage_string[coverage] );
 354                 layerNode->setDoubleValue( "elevation-ft", _station_elevation + LAYER_BOTTOM_STATION_OFFSET );
 355                 layerNode->setDoubleValue( "thickness-ft", thickness );
 356                 layerNode->setDoubleValue( "visibility-m", _min_visibility );
 357                 layerNode->setDoubleValue( "alpha", alpha );
 358                 _min_visibility = _max_visibility =
 359                   fgGetDouble("/environment/params/fog-mist-haze-layer/visibility-above-layer-m",20000.0); // assume good visibility above the fog
 360                 layerOffset = 1;  // shudder
 361             }
 362         }
 363
 364         for( unsigned i = 0; i < 5-layerOffset; i++ ) {
 365             SGPropertyNode_ptr layerNode = cloudsNode->getChild(LAYER, i+layerOffset, true );
 366             SGMetarCloud::Coverage coverage = i < metarClouds.size() ? metarClouds[i].getCoverage() : SGMetarCloud::COVERAGE_CLEAR;
 367             double elevation =
 368                 i >= metarClouds.size() || coverage == SGMetarCloud::COVERAGE_CLEAR ?
 369                 -9999.0 :
 370                 metarClouds[i].getAltitude_ft() + _station_elevation;
 371
 372             layerNode->setDoubleValue( "alpha", 1.0 );
 373             layerNode->setStringValue( "coverage", coverage_string[coverage] );
 374             layerNode->setDoubleValue( "coverage-type", SGCloudLayer::getCoverageType(coverage_string[coverage]) );
 375             layerNode->setDoubleValue( "elevation-ft", elevation );
 376             layerNode->setDoubleValue( "thickness-ft", thickness_value[coverage]);
 377             layerNode->setDoubleValue( "span-m", 40000 );
 378             layerNode->setDoubleValue( "visibility-m", 50.0 );
 379         }
 380     }
 381
 382     _rain = m->getRain();
 383     _hail = m->getHail();
 384     _snow = m->getSnow();
 385     _snow_cover = m->getSnowCover();
 386     _metarValidNode->setBoolValue(true);
 387 }
 388
 389 void MetarProperties::setStationId( const std::string & value )
 390 {
 391     set_station_id(simgear::strutils::strip(value).c_str());
 392 }
 393
 394 double MetarProperties::get_magnetic_variation_deg() const
 395 {
 396   return _magneticVariation->get_variation_deg( _station_longitude, _station_latitude, _station_elevation );
 397 }
 398
 399 double MetarProperties::get_magnetic_dip_deg() const
 400 {
 401   return _magneticVariation->get_dip_deg( _station_longitude, _station_latitude, _station_elevation );
 402 }
 403
 404 static inline void calc_wind_hs( double north_fps, double east_fps, int & heading_deg, double & speed_kt )
 405 {
 406     speed_kt = sqrt((north_fps)*(north_fps)+(east_fps)*(east_fps)) * 3600.0 / (SG_NM_TO_METER * SG_METER_TO_FEET);
 407     heading_deg = SGMiscd::roundToInt(
 408         SGMiscd::normalizeAngle2( atan2( east_fps, north_fps ) ) * SGD_RADIANS_TO_DEGREES );
 409 }
 410
 411 void MetarProperties::set_wind_from_north_fps( double value )
 412 {
 413     _wind_from_north_fps = value;
 414     calc_wind_hs( _wind_from_north_fps, _wind_from_east_fps, _base_wind_dir, _wind_speed );
 415 }
 416
 417 void MetarProperties::set_wind_from_east_fps( double value )
 418 {
 419     _wind_from_east_fps = value;
 420     calc_wind_hs( _wind_from_north_fps, _wind_from_east_fps, _base_wind_dir, _wind_speed );
 421 }
 422
 423 static inline void calc_wind_ne( double heading_deg, double speed_kt, double & north_fps, double & east_fps )
 424 {
 425     double speed_fps = speed_kt * SG_NM_TO_METER * SG_METER_TO_FEET / 3600.0;
 426     north_fps = speed_fps * cos(heading_deg * SGD_DEGREES_TO_RADIANS);
 427     east_fps = speed_fps * sin(heading_deg * SGD_DEGREES_TO_RADIANS);
 428 }
 429
 430 void MetarProperties::set_base_wind_dir( double value )
 431 {
 432     _base_wind_dir = value;
 433     calc_wind_ne( (double)_base_wind_dir, _wind_speed, _wind_from_north_fps, _wind_from_east_fps );
 434 }
 435
 436 void MetarProperties::set_wind_speed( double value )
 437 {
 438     _wind_speed = value;
 439     calc_wind_ne( (double)_base_wind_dir, _wind_speed, _wind_from_north_fps, _wind_from_east_fps );
 440 }
 441
 442
 443 } // namespace Environment