Added support for DEM data (SRTM HGT) elevation sources

src/data/dem.cpp

@@ -0,0 +1,58 @@
+#include <QtEndian>
+#include "common/coordinates.h"
+#include "dem.h"
+
+#define SRTM3_SAMPLES 1201
+#define SRTM1_SAMPLES 3601
+
+#define SRTM_SIZE(samples) \
+	((samples) * (samples) * 2)
+
+
+static qreal height(const Coordinates &c, const QByteArray data)
+{
+	int samples;
+
+	if (data.size() == SRTM_SIZE(SRTM3_SAMPLES))
+		samples = SRTM3_SAMPLES;
+	else if (data.size() == SRTM_SIZE(SRTM1_SAMPLES))
+		samples = SRTM1_SAMPLES;
+	else
+		return NAN;
+
+	int lat = int(qRound((c.lat() - int(c.lat())) * (samples - 1)));
+	int lon = int(qRound((c.lon() - int(c.lon())) * (samples - 1)));
+
+	int pos = ((samples - 1 - lat) * samples + lon) * 2;
+	qint16 val = qFromBigEndian(*((const qint16*)(data.constData() + pos)));
+
+	return (val == -32768) ? NAN : val;
+}
+
+QString DEM::fileName(const Key &key) const
+{
+	const char ns = (key.lat >= 0) ? 'N' : 'S';
+	const char ew = (key.lon >= 0) ? 'E' : 'W';
+
+	QString basename = QString("%1%2%3%4.hgt").arg(ns)
+	  .arg(qAbs(key.lat), 2, 10, QChar('0')).arg(ew)
+	  .arg(qAbs(key.lon), 3, 10, QChar('0'));
+	return _dir.absoluteFilePath(basename);
+}
+
+qreal DEM::elevation(const Coordinates &c)
+{
+	Key k((int)c.lon(), (int)c.lat());
+
+	QMap<Key, QByteArray>::const_iterator it(_data.find(k));
+	if (it == _data.constEnd()) {
+		QFile file(fileName(k));
+		if (!file.open(QIODevice::ReadOnly))
+			return NAN;
+		else {
+			it = _data.insert(k, file.readAll());
+			return height(c, *it);
+		}
+	} else
+		return height(c, *it);
+}

src/data/dem.h

@@ -0,0 +1,43 @@
+#ifndef DEM_H
+#define DEM_H
+
+#include <QMap>
+#include <QByteArray>
+#include <QDir>
+
+class QDir;
+class Coordinates;
+
+class DEM
+{
+public:
+	DEM() {}
+	DEM(const QDir &dir) : _dir(dir) {}
+	qreal elevation(const Coordinates &c);
+
+private:
+	struct Key {
+		int lon;
+		int lat;
+
+		Key(int lon, int lat) : lon(lon), lat(lat) {}
+
+		bool operator<(const Key &other) const
+		{
+			if (lon < other.lon)
+				return true;
+			else if (lon > other.lon)
+				return false;
+			else
+				return (lat < other.lat);
+		}
+
+	};
+
+	QString fileName(const Key &key) const;
+
+	QDir _dir;
+	QMap<Key, QByteArray> _data;
+};
+
+#endif // DEM_H

src/data/track.cpp

@@ -1,5 +1,7 @@
+#include "dem.h"
 #include "track.h"
 
+
 int Track::_elevationWindow = 3;
 int Track::_speedWindow = 5;
 int Track::_heartRateWindow = 3;
@@ -11,6 +13,9 @@ int Track::_pauseInterval = 10;
 
 bool Track::_outlierEliminate = true;
 bool Track::_useReportedSpeed = false;
+bool Track::_useDEMElevation = false;
+
+DEM Track::_dem;
 
 
 static qreal median(QVector<qreal> &v)
@@ -147,10 +152,19 @@ Graph Track::elevation() const
 {
 	Graph raw;
 
-	for (int i = 0; i < _data.size(); i++)
-		if (_data.at(i).hasElevation() && !_outliers.contains(i))
+	for (int i = 0; i < _data.size(); i++) {
+		if (_outliers.contains(i))
+			continue;
+
+		if (_data.at(i).hasElevation() && !_useDEMElevation)
 			raw.append(GraphPoint(_distance.at(i), _time.at(i),
 			  _data.at(i).elevation()));
+		else {
+			qreal elevation = _dem.elevation(_data.at(i).coordinates());
+			if (!std::isnan(elevation))
+				raw.append(GraphPoint(_distance.at(i), _time.at(i), elevation));
+		}
+	}
 
 	return filter(raw, _elevationWindow);
 }

src/data/track.h

@@ -4,8 +4,10 @@
 #include <QVector>
 #include <QSet>
 #include <QDateTime>
+#include <QDir>
 #include "trackdata.h"
 #include "graph.h"
+#include "dem.h"
 #include "path.h"
 
 
@@ -44,6 +46,8 @@ public:
 	static void setOutlierElimination(bool eliminate)
 	  {_outlierEliminate = eliminate;}
 	static void useReportedSpeed(bool use) {_useReportedSpeed = use;}
+	static void useDEMElevation(bool use) {_useDEMElevation = use;}
+	static void setDEMDir(const QDir &dir) {_dem = DEM(dir);}
 
 private:
 	bool discardStopPoint(int i) const;
@@ -68,6 +72,8 @@ private:
 	static qreal _pauseSpeed;
 	static int _pauseInterval;
 	static bool _useReportedSpeed;
+	static bool _useDEMElevation;
+	static DEM _dem;
 };
 
 #endif // TRACK_H