CityGmlParser.java

/*-
 *  Copyright 2020 Beuth Hochschule für Technik Berlin, Hochschule für Technik Stuttgart
 * 
 *  This file is part of CityDoctor2.
 *
 *  CityDoctor2 is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  CityDoctor2 is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with CityDoctor2.  If not, see <https://www.gnu.org/licenses/>.
 */
package de.hft.stuttgart.citydoctor2.parser;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.util.Enumeration;
import java.util.List;
import java.util.ServiceLoader;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

import javax.xml.XMLConstants;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.namespace.QName;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.citygml4j.CityGMLContext;
import org.citygml4j.builder.jaxb.CityGMLBuilder;
import org.citygml4j.builder.jaxb.CityGMLBuilderException;
import org.citygml4j.model.citygml.CityGML;
import org.citygml4j.model.citygml.ade.ADEComponent;
import org.citygml4j.model.citygml.ade.ADEException;
import org.citygml4j.model.citygml.ade.binding.ADEContext;
import org.citygml4j.model.citygml.ade.generic.ADEGenericElement;
import org.citygml4j.model.citygml.core.AbstractCityObject;
import org.citygml4j.model.citygml.core.CityModel;
import org.citygml4j.model.citygml.core.CityObjectMember;
import org.citygml4j.model.gml.feature.AbstractFeature;
import org.citygml4j.model.module.citygml.CityGMLVersion;
import org.citygml4j.xml.io.CityGMLInputFactory;
import org.citygml4j.xml.io.CityGMLOutputFactory;
import org.citygml4j.xml.io.reader.CityGMLReadException;
import org.citygml4j.xml.io.reader.CityGMLReader;
import org.citygml4j.xml.io.reader.FeatureReadMode;
import org.citygml4j.xml.io.reader.ParentInfo;
import org.citygml4j.xml.io.writer.CityGMLWriteException;
import org.citygml4j.xml.io.writer.CityModelInfo;
import org.citygml4j.xml.io.writer.CityModelWriter;
import org.osgeo.proj4j.BasicCoordinateTransform;
import org.osgeo.proj4j.CRSFactory;
import org.osgeo.proj4j.CoordinateReferenceSystem;
import org.osgeo.proj4j.ProjCoordinate;
import org.osgeo.proj4j.proj.Projection;
import org.osgeo.proj4j.units.Units;
import org.w3c.dom.DOMException;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
import org.xml.sax.SAXParseException;

import de.hft.stuttgart.citydoctor2.datastructure.CityDoctorModel;
import de.hft.stuttgart.citydoctor2.datastructure.CityObject;
import de.hft.stuttgart.citydoctor2.mapper.FeatureMapper;
import de.hft.stuttgart.citydoctor2.math.Vector3d;
import de.hft.stuttgart.citydoctor2.utils.Localization;
import de.hft.stuttgart.quality.QualityADEModule;

/**
 * Utility class to parse CityGML files.
 * 
 * @author Matthias Betz
 *
 */
public class CityGmlParser {

	private static final Logger logger = LogManager.getLogger(CityGmlParser.class);

	private static final CRSFactory CRS_FACTORY = new CRSFactory();
	// EPSG:31467
	private static final Pattern P_EPSG = Pattern.compile("^(EPSG:\\d+)$");
	// urn:ogc:def:crs,crs:EPSG:6.12:31467,crs:EPSG:6.12:5783
	// or
	// urn:ogc:def:crs,crs:EPSG::28992
	private static final Pattern P_OGC = Pattern.compile("urn:ogc:def:crs,crs:EPSG:[\\d\\.]*:([\\d]+)\\D*");

	private static final Pattern P_OGC2 = Pattern.compile("urn:ogc:def:crs:EPSG:[\\d\\.]*:([\\d]+)\\D*");

	// urn:adv:crs:DE_DHDN_3GK3*DE_DHHN92_NH
	// urn:adv:crs:ETRS89_UTM32*DE_DHHN92_NH
	private static final Pattern P_URN = Pattern.compile("urn:adv:crs:([^\\*]+)");

	private static final SAXParserFactory FACTORY;

	static {
		FACTORY = SAXParserFactory.newInstance();
		try {
			FACTORY.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
		} catch (SAXNotRecognizedException | SAXNotSupportedException | ParserConfigurationException e) {
			logger.catching(e);
		}
	}

	private CityGmlParser() {
		// only static access
	}

	public static CityDoctorModel parseCityGmlFile(String file, ParserConfiguration config)
			throws CityGmlParseException, InvalidGmlFileException {
		return parseCityGmlFile(file, config, null, null);
	}

	public static CityDoctorModel parseCityGmlFile(String file, ParserConfiguration config, ProgressListener l)
			throws CityGmlParseException, InvalidGmlFileException {
		return parseCityGmlFile(file, config, l, null);
	}

	public static CityDoctorModel parseCityGmlFile(String filePath, ParserConfiguration config, ProgressListener l,
			ValidationEventHandler handler) throws CityGmlParseException, InvalidGmlFileException {
		File file = new File(filePath);
		try {
			parseEpsgCodeFromFile(file, config);
			CityGMLBuilder builder = setupCityGmlBuilder();
			CityGMLInputFactory inputFactory = setupGmlReader(builder, config);
			if (handler != null) {
				inputFactory.setValidationEventHandler(handler);
			}
			// try with resources for automatic closing
			try (ObservedInputStream ois = new ObservedInputStream(file)) {
				if (l != null) {
					ois.addListener(l::updateProgress);
				}
				return readAndKeepFeatures(config, file, inputFactory, ois);
			}
		} catch (CityGMLReadException e) {
			if (e.getCause() instanceof SAXParseException) {
				throw new InvalidGmlFileException(
						Localization.getText("CityGmlParser.notValidGmlFile") + e.getCause().getMessage(), e);
			}
			throw new CityGmlParseException(e);
		} catch (IOException | CityGMLBuilderException | ParserConfigurationException | SAXException | ADEException e) {
			throw new CityGmlParseException(e);
		} catch (DOMException e) {
			// the citygml4j split per feature tries to insert an element
			// this sometimes fails because of namespace mismatch
			// fallback solution is to parse the whole file at once
			// problems with memory consumption may arise
			try {
				if (logger.isWarnEnabled()) {
					logger.warn(Localization.getText("CityGmlParser.chunkReadFailed"), e);
				}
				return parseCityGmlFileComplete(file, config, l);
			} catch (CityGMLBuilderException | CityGMLReadException | IOException e1) {
				throw new CityGmlParseException(e1);
			}
		}
	}

	private static CityDoctorModel readAndKeepFeatures(ParserConfiguration config, File file,
			CityGMLInputFactory inputFactory, ObservedInputStream ois) throws CityGMLReadException {
		try (CityGMLReader reader = inputFactory.createCityGMLReader(file.getAbsolutePath(), ois)) {
			FeatureMapper mapper = new FeatureMapper(config, file);
			while (reader.hasNext()) {
				CityGML chunk = reader.nextFeature();
				if (chunk instanceof AbstractCityObject) {
					AbstractCityObject ag = (AbstractCityObject) chunk;
					ag.accept(mapper);
				} else if (chunk instanceof CityModel) {
					CityModel cModel = (CityModel) chunk;
					cModel.unsetCityObjectMember();
					mapper.setCityModel(cModel);
				}
			}
			if (logger.isInfoEnabled()) {
				logger.info(Localization.getText("CityGmlParser.parsedObjects"),
						mapper.getModel().getNumberOfFeatures());
			}
			return mapper.getModel();
		}
	}

	private static CityDoctorModel parseCityGmlFileComplete(File file, ParserConfiguration config, ProgressListener l)
			throws CityGMLBuilderException, IOException, CityGMLReadException, CityGmlParseException {
		CityGMLContext context = CityGMLContext.getInstance();
		CityGMLBuilder builder = context.createCityGMLBuilder();
		CityGMLInputFactory inputFactory = builder.createCityGMLInputFactory();
		inputFactory.setProperty(CityGMLInputFactory.FAIL_ON_MISSING_ADE_SCHEMA, false);
		inputFactory.setProperty(CityGMLInputFactory.USE_VALIDATION, config.getValidate());

		try (ObservedInputStream ois = new ObservedInputStream(file)) {
			if (l != null) {
				ois.addListener(l::updateProgress);
			}
			try (CityGMLReader reader = inputFactory.createCityGMLReader(file.getAbsolutePath(), ois)) {
				FeatureMapper mapper = new FeatureMapper(config, file);

				CityGML chunk = reader.nextFeature();
				if (!(chunk instanceof CityModel)) {
					throw new CityGmlParseException("Did not read CityModel as first element of gml file.");
				}
				CityModel model = (CityModel) chunk;
				mapper.setCityModel(model);
				if (model.isSetCityObjectMember()) {
					for (CityObjectMember com : model.getCityObjectMember()) {
						if (com.isSetCityObject()) {
							com.getCityObject().accept(mapper);
						}
					}
				}
				model.unsetCityObjectMember();
				return mapper.getModel();
			}
		}

	}

	private static CityGMLInputFactory setupGmlReader(CityGMLBuilder builder, ParserConfiguration config)
			throws CityGMLBuilderException, ADEException {
		CityGMLInputFactory inputFactory = builder.createCityGMLInputFactory();
		inputFactory.setProperty(CityGMLInputFactory.FEATURE_READ_MODE, FeatureReadMode.SPLIT_PER_FEATURE);
		if (config != null) {
			inputFactory.setProperty(CityGMLInputFactory.USE_VALIDATION, config.getValidate());
		}
		inputFactory.setProperty(CityGMLInputFactory.FAIL_ON_MISSING_ADE_SCHEMA, false);
		inputFactory.setProperty(CityGMLInputFactory.EXCLUDE_FROM_SPLITTING,
				new QName[] { new QName("WallSurface"), new QName("RoofSurface"), new QName("GroundSurface"),
						new QName("CeilingSurface"), new QName("ClosureSurface"), new QName("FloorSurface"),
						new QName("InteriorWallSurface"), new QName("OuterCeilingSurface"),
						new QName("OuterFloorSurface"), new QName("BuildingInstallation"), new QName("BuildingPart"),
						new QName("Door"), new QName("Window") });
		return inputFactory;
	}

	private static CityGMLBuilder setupCityGmlBuilder() throws ADEException, CityGMLBuilderException {
		CityGMLContext context = CityGMLContext.getInstance();

		// setup energy ade stuff, so the parser doesn't crash on encountering this
		if (!context.hasADEContexts()) {
			for (ADEContext adeContext : ServiceLoader.load(ADEContext.class)) {
				context.registerADEContext(adeContext);
			}
		}
		CityGMLBuilder builder = context.createCityGMLBuilder(CityGmlParser.class.getClassLoader());
		return builder;
	}

	public static void streamCityGml(String file, ParserConfiguration config, CityGmlConsumer cityObjectConsumer,
			String outputFile) throws CityGmlParseException {
		File f = new File(file);
		streamCityGml(f, config, null, cityObjectConsumer, outputFile);
	}

	public static void streamCityGml(File file, ParserConfiguration config, ProgressListener l,
			CityGmlConsumer cityObjectConsumer, String outputFile) throws CityGmlParseException {
		try {
			if (getExtension(file.getName()).equals("zip")) {
				streamZipFile(file, config);
			}
			parseEpsgCodeFromFile(file, config);
			CityGMLBuilder builder = setupCityGmlBuilder();
			startReadingCityGml(file, config, l, cityObjectConsumer, builder, outputFile);
		} catch (CityGMLBuilderException | IOException | ParserConfigurationException | SAXException | ADEException e) {
			throw new CityGmlParseException(e);
		}
	}

	private static void startReadingCityGml(File file, ParserConfiguration config, ProgressListener l,
			CityGmlConsumer cityObjectConsumer, CityGMLBuilder builder, String outputFile)
			throws CityGMLBuilderException, ADEException {
		try (ObservedInputStream ois = new ObservedInputStream(file)) {
			if (l != null) {
				ois.addListener(l::updateProgress);
			}
			readAndDiscardFeatures(file, config, builder, ois, cityObjectConsumer, outputFile);
		} catch (IOException e) {
			logger.error(Localization.getText("CityGmlParser.errorReadingGmlFile"), e.getMessage());
			logger.catching(Level.ERROR, e);
		}
	}

	private static void streamZipFile(File file, ParserConfiguration config) throws CityGmlParseException {
		try (ZipFile zip = new ZipFile(file)) {
			Enumeration<? extends ZipEntry> entries = zip.entries();
			while (entries.hasMoreElements()) {
				ZipEntry ze = entries.nextElement();
				BufferedInputStream bis = new BufferedInputStream(zip.getInputStream(ze));
				parseEpsgCodeFromStream(bis, config);
			}
		} catch (IOException e) {
			throw new UncheckedIOException(e);
		} catch (ParserConfigurationException | SAXException e) {
			throw new CityGmlParseException(e);
		}
	}

	public static String getExtension(String fileName) {
		char ch;
		int len;
		if (fileName == null || (len = fileName.length()) == 0 || (ch = fileName.charAt(len - 1)) == '/' || ch == '\\'
				|| ch == '.') {
			return "";
		}
		int dotInd = fileName.lastIndexOf('.');
		int sepInd = Math.max(fileName.lastIndexOf('/'), fileName.lastIndexOf('\\'));
		if (dotInd <= sepInd)
			return "";
		else
			return fileName.substring(dotInd + 1).toLowerCase();
	}

	public static void streamCityGml(File file, ParserConfiguration parserConfig, CityGmlConsumer cityObjectConsumer,
			String outputFile) throws CityGmlParseException {
		streamCityGml(file, parserConfig, null, cityObjectConsumer, outputFile);
	}

	/**
	 * The srsName (The name by which this reference system is identified) inside
	 * the CityGML file can have multiple formats. This method tries to parse the
	 * string and detect the corresponding reference system. If it is found, it
	 * returns a proj4j.CoordinateReferenceSystem. It throws an
	 * IllegalArgumentException otherwise.
	 * 
	 * This method should be able to parse any EPSG id : e.g. "EPSG:1234". German
	 * Citygmls might also have "DE_DHDN_3GK3" or "ETRS89_UTM32" as srsName, so
	 * those are also included. It isn't guaranteed that those formats are correctly
	 * parsed, though.
	 * 
	 * The EPSG ids and parameters are defined in resources ('nad/epsg') inside
	 * proj4j-0.1.0.jar. Some EPSG ids are missing though, e.g. 7415
	 * 
	 * @param srsName
	 * @return CoordinateReferenceSystem
	 */
	private static CoordinateReferenceSystem crsFromSrsName(String srsName) {
		srsName = srsName.trim();
		Matcher mEPSG = P_EPSG.matcher(srsName);
		if (mEPSG.find()) {
			if ("EPSG:4979".contentEquals(srsName)) {
				srsName = "EPSG:4236";
			} else if ("EPSG:7415".contentEquals(srsName)) {
				return CRS_FACTORY.createFromParameters("EPSG:7415",
						"+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel +towgs84=565.417,50.3319,465.552,-0.398957,0.343988,-1.8774,4.0725 +units=m +no_defs");
			}
			return CRS_FACTORY.createFromName(srsName);
		}

		Matcher mOGC = P_OGC.matcher(srsName);
		if (mOGC.find()) {
			return CRS_FACTORY.createFromName("EPSG:" + mOGC.group(1));
		}
		Matcher mOGC2 = P_OGC2.matcher(srsName);
		if (mOGC2.find()) {
			return CRS_FACTORY.createFromName("EPSG:" + mOGC2.group(1));
		}
		Matcher mURN = P_URN.matcher(srsName);
		// NOTE: Could use a HashMap if the switch/case becomes too long.
		if (mURN.find()) {
			switch (mURN.group(1)) {
			case "DE_DHDN_3GK2":
				return CRS_FACTORY.createFromName("EPSG:31466");
			case "DE_DHDN_3GK3":
				return CRS_FACTORY.createFromName("EPSG:31467");
			case "DE_DHDN_3GK4":
				return CRS_FACTORY.createFromName("EPSG:31468");
			case "DE_DHDN_3GK5":
				return CRS_FACTORY.createFromName("EPSG:31469");
			case "ETRS89_UTM32":
				return CRS_FACTORY.createFromName("EPSG:25832");
			default:
				return null;
			}
		}
		if (srsName.equals("http://www.opengis.net/def/crs/EPSG/0/6697")) {
			return CRS_FACTORY.createFromParameters("EPSG:6697", "+proj=longlat +ellps=GRS80 +no_defs ");
		}
		return null;
	}

	public static CityModel parseOnlyCityModel(File inputFile) throws CityGmlParseException {
		try {
			CityGMLBuilder setupCityGmlBuilder = setupCityGmlBuilder();
			CityGMLInputFactory inputFactory = setupGmlReader(setupCityGmlBuilder, null);
			try (CityGMLReader reader = inputFactory.createCityGMLReader(inputFile)) {
				while (reader.hasNext()) {
					CityGML chunk = reader.nextFeature();
					if (chunk instanceof CityModel) {
						CityModel cModel = (CityModel) chunk;
						cModel.unsetCityObjectMember();
						return cModel;
					}
				}
			}
		} catch (CityGMLBuilderException | CityGMLReadException | ADEException e) {
			throw new CityGmlParseException(e);
		}
		throw new CityGmlParseException("Did not find any CityModel in CityGML file");
	}

	private static void readAndDiscardFeatures(File file, ParserConfiguration config, CityGMLBuilder builder,
			ObservedInputStream ois, CityGmlConsumer cityObjectConsumer, String outputFile)
			throws CityGMLBuilderException, ADEException {
		CityGMLInputFactory inputFactory = setupGmlReader(builder, config);
		try (CityGMLReader reader = inputFactory.createCityGMLReader(file.getAbsolutePath(), ois);
				CityModelWriter writer = createCityModelWriter(builder, outputFile)) {
			FeatureMapper mapper = new FeatureMapper(config, file);
			CityDoctorModel model = mapper.getModel();
			boolean isInitialized = false;
			CityModelInfo cityModelInfo = null;
			while (reader.hasNext()) {
				CityGML chunk = reader.nextFeature();
				if (!isInitialized && writer != null) {
					ParentInfo parentInfo = reader.getParentInfo();
					cityModelInfo = new CityModelInfo(parentInfo);
					writer.setCityModelInfo(cityModelInfo);
					writer.writeStartDocument();
					isInitialized = true;
				}
				if (chunk instanceof AbstractCityObject) {
					AbstractCityObject ag = (AbstractCityObject) chunk;
					ag.accept(mapper);
					drainCityModel(model, cityObjectConsumer);
					writeAbstractCityObject(writer, ag);
				} else if (chunk instanceof CityModel) {
					CityModel cModel = (CityModel) chunk;
					cModel.unsetCityObjectMember();
					mapper.setCityModel(cModel);
					cityObjectConsumer.accept(cModel);
					writeCityModel(writer, cityModelInfo, cModel);
				} else if (chunk instanceof AbstractFeature && writer != null) {
					writer.writeFeatureMember((AbstractFeature) chunk);
				}

			}
			// end of stream
			logger.debug("End of gml file stream");
		} catch (CityGMLReadException e) {
			logger.error(Localization.getText("CityGmlParser.errorReadingGmlFile"), e.getMessage(), e);
		} catch (CityGMLWriteException e) {
			logger.error(Localization.getText("CityGmlParser.errorWritingGmlFile"), e.getMessage(), e);
		}
	}

	private static void writeAbstractCityObject(CityModelWriter writer, AbstractCityObject ag)
			throws CityGMLWriteException {
		if (writer != null) {
			writer.writeFeatureMember(ag);
		}
	}

	private static void writeCityModel(CityModelWriter writer, CityModelInfo cityModelInfo, CityModel cModel)
			throws CityGMLWriteException {
		if (writer != null) {
			for (ADEGenericElement genEle : cModel.getGenericADEElement()) {
				cityModelInfo.addGenericADEElement(genEle);
			}
			for (ADEComponent adeComp : cModel.getGenericApplicationPropertyOfCityModel()) {
				cityModelInfo.addGenericApplicationPropertyOfCityModel(adeComp);
			}
			writer.writeEndDocument();
		}
	}

	private static CityModelWriter createCityModelWriter(CityGMLBuilder builder, String outputFile) throws CityGMLWriteException {
		if (outputFile == null) {
			return null;
		}
		CityGMLOutputFactory factory = builder.createCityGMLOutputFactory();
		CityModelWriter writer = factory.createCityModelWriter(new File(outputFile));
		writer.setPrefix("qual", QualityADEModule.NAMESPACE_URI);
		writer.setSchemaLocation(QualityADEModule.NAMESPACE_URI,
				"https://transfer.hft-stuttgart.de/pages/qualityade/0.1/qualityAde.xsd");
		writer.setIndentString("  ");
		writer.setPrefixes(CityGMLVersion.DEFAULT);
		writer.setSchemaLocations(CityGMLVersion.DEFAULT);
		return writer;
	}

	private static void parseEpsgCodeFromFile(File file, ParserConfiguration config)
			throws IOException, ParserConfigurationException, SAXException {
		try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file))) {
			parseEpsgCodeFromStream(bis, config);
		}
	}

	private static void parseEpsgCodeFromStream(InputStream is, ParserConfiguration config)
			throws ParserConfigurationException, SAXException {
		SAXParser parser = FACTORY.newSAXParser();
		CityGmlHandler handler = new CityGmlHandler();
		try {
			parser.parse(new InputSource(is), handler);
		} catch (EnvelopeFoundException e) {
			try {
				parseCoordinateSystem(config, handler);
			} catch (Exception e2) {
				logger.debug("Exception while parsing for EPSG code", e2);
				if (logger.isWarnEnabled()) {
					logger.warn(Localization.getText("CityGmlParser.noEPSG"));
				}
			}
		} catch (Exception e) {
			logger.debug("Exception while parsing for EPSG code", e);
			if (logger.isWarnEnabled()) {
				logger.warn(Localization.getText("CityGmlParser.noEPSG"));
			}
		}
	}

	private static void parseCoordinateSystem(ParserConfiguration config, CityGmlHandler handler) {
		if (handler.getEpsg() == null) {
			return;
		}
		CoordinateReferenceSystem crs = crsFromSrsName(handler.getEpsg());
		if (crs == null) {
			// could not find a coordinate system for srsName
			// assuming metric system
			return;
		}
		ProjectionUnitExtractor extractor = new ProjectionUnitExtractor(crs.getProjection());
		if (extractor.getUnit() == Units.METRES) {
			// coordinate system is in meters, do not convert
			if (logger.isInfoEnabled()) {
				logger.info(Localization.getText("CityGmlParser.noConversionNeeded"));
			}
			return;
		}
		parseMeterConversion(config, crs);
		Vector3d low = handler.getLowerCorner();
		Vector3d up = handler.getUpperCorner();
		double centerLong = low.getX() + ((up.getX() - low.getX()) / 2);
		double centerLat = low.getY() + ((up.getY() - low.getY()) / 2);
		if (!crs.getName().equals("EPSG:4326")) {
			// need to convert coordinates first to WGS84, then find UTM Zone
			CoordinateReferenceSystem wgs84 = crsFromSrsName("EPSG:4326");
			ProjCoordinate p1 = new ProjCoordinate();
			p1.setValue(centerLong, centerLat);
			ProjCoordinate p2 = new ProjCoordinate();
			BasicCoordinateTransform bct = new BasicCoordinateTransform(crs, wgs84);
			bct.transform(p1, p2);
			centerLong = p2.y;
			centerLat = p2.x;
		}
		int zone = (int) (31 + Math.round(centerLong / 6));
		CoordinateReferenceSystem utm;
		if (centerLat < 0) {
			// south
			logger.info("Converting coordiante system to UTM zone {}S", zone);
			utm = CRS_FACTORY.createFromParameters("UTM", "+proj=utm +ellps=WGS84 +units=m +zone=" + zone + " +south");
		} else {
			// north
			logger.info("Converting coordiante system to UTM zone {}N", zone);
		utm = CRS_FACTORY.createFromParameters("UTM", "+proj=utm +ellps=WGS84 +units=m +zone=" + zone);
		}
		config.setCoordinateSystem(crs, utm);
	}

	private static void parseMeterConversion(ParserConfiguration config, CoordinateReferenceSystem crs) {
		Projection projection = crs.getProjection();
		double fromMetres = projection.getFromMetres();
		if (fromMetres > 0) {
			// also transform height information
			config.setFromMetres(fromMetres);
		} else {
			config.setFromMetres(1.0);
		}
	}

	private static void drainCityModel(CityDoctorModel model, CityGmlConsumer cityObjectConsumer) {
		drainCityObjectList(model.getBuildings(), cityObjectConsumer);
		drainCityObjectList(model.getBridges(), cityObjectConsumer);
		drainCityObjectList(model.getVegetation(), cityObjectConsumer);
		drainCityObjectList(model.getLand(), cityObjectConsumer);
		drainCityObjectList(model.getTransportation(), cityObjectConsumer);
		drainCityObjectList(model.getWater(), cityObjectConsumer);
	}

	private static void drainCityObjectList(List<? extends CityObject> objects, CityGmlConsumer cityObjectConsumer) {
		for (CityObject co : objects) {
			cityObjectConsumer.accept(co);
		}
		objects.clear();
	}
}