diff --git a/src/lib/marble/geodata/graphicsitem/BuildingGeoPolygonGraphicsItem.cpp b/src/lib/marble/geodata/graphicsitem/BuildingGeoPolygonGraphicsItem.cpp
index bee2e30a0..7df35dc6a 100644
--- a/src/lib/marble/geodata/graphicsitem/BuildingGeoPolygonGraphicsItem.cpp
+++ b/src/lib/marble/geodata/graphicsitem/BuildingGeoPolygonGraphicsItem.cpp
@@ -1,516 +1,524 @@
 //
 // This file is part of the Marble Virtual Globe.
 //
 // This program is free software licensed under the GNU LGPL. You can
 // find a copy of this license in LICENSE.txt in the top directory of
 // the source code.
 //
 // Copyright 2011      Konstantin Oblaukhov <oblaukhov.konstantin@gmail.com>
 //
 
 #include "BuildingGeoPolygonGraphicsItem.h"
 
 #include "MarbleDebug.h"
 #include "ViewportParams.h"
 #include "GeoDataTypes.h"
 #include "GeoDataPlacemark.h"
 #include "GeoDataLinearRing.h"
 #include "GeoDataPolygon.h"
 #include "GeoDataPolyStyle.h"
 #include "OsmPlacemarkData.h"
 #include "GeoPainter.h"
 
 #include <QScreen>
 #include <QApplication>
 
 namespace Marble
 {
 
 BuildingGeoPolygonGraphicsItem::BuildingGeoPolygonGraphicsItem(const GeoDataPlacemark *placemark,
                                                                const GeoDataPolygon *polygon)
     : AbstractGeoPolygonGraphicsItem(placemark, polygon)
     , m_buildingHeight(extractBuildingHeight(*placemark))
     , m_buildingLabel(extractBuildingLabel(*placemark))
     , m_entries(extractNamedEntries(*placemark))
     , m_hasInnerBoundaries(false)
 {
     setZValue(this->zValue() + m_buildingHeight);
     Q_ASSERT(m_buildingHeight > 0.0);
 
     QStringList paintLayers;
     paintLayers << QStringLiteral("Polygon/Building/frame")
                 << QStringLiteral("Polygon/Building/roof");
     setPaintLayers(paintLayers);
 }
 
 BuildingGeoPolygonGraphicsItem::BuildingGeoPolygonGraphicsItem(const GeoDataPlacemark *placemark,
                                                                const GeoDataLinearRing* ring)
     : AbstractGeoPolygonGraphicsItem(placemark, ring)
     , m_buildingHeight(extractBuildingHeight(*placemark))
     , m_buildingLabel(extractBuildingLabel(*placemark))
     , m_entries(extractNamedEntries(*placemark))
 {
     setZValue(this->zValue() + m_buildingHeight);
     Q_ASSERT(m_buildingHeight > 0.0);
 
     QStringList paintLayers;
     paintLayers << QStringLiteral("Polygon/Building/frame")
                 << QStringLiteral("Polygon/Building/roof");
     setPaintLayers(paintLayers);
 }
 
 void BuildingGeoPolygonGraphicsItem::initializeBuildingPainting(const GeoPainter* painter, const ViewportParams *viewport,
                                                                 bool &drawAccurate3D, bool &isCameraAboveBuilding ) const
 {
     drawAccurate3D = false;
     isCameraAboveBuilding = false;
 
     auto const screen = QApplication::screens().first();
     double const physicalSize = 1.0; // mm
     int const pixelSize = qRound(physicalSize * screen->physicalDotsPerInch() / (IN2M * M2MM));
 
     QPointF offsetAtCorner = buildingOffset(QPointF(0, 0), viewport, &isCameraAboveBuilding);
     qreal maxOffset = qMax( qAbs( offsetAtCorner.x() ), qAbs( offsetAtCorner.y() ) );
     drawAccurate3D = painter->mapQuality() == HighQuality ? maxOffset > pixelSize : maxOffset > 1.5 * pixelSize;
 }
 
 void BuildingGeoPolygonGraphicsItem::updatePolygons( const ViewportParams *viewport,
                                                      QVector<QPolygonF*>& outerPolygons,
                                                      QVector<QPolygonF*>& innerPolygons,
                                                      bool &hasInnerBoundaries )
 {
     // Since subtracting one fully contained polygon from another results in a single
     // polygon with a "connecting line" between the inner and outer part we need
     // to first paint the inner area with no pen and then the outlines with the correct pen.
     hasInnerBoundaries = polygon() ? !polygon()->innerBoundaries().isEmpty() : false;
     if (polygon()) {
         if (hasInnerBoundaries) {
             screenPolygons(viewport, polygon(), innerPolygons, outerPolygons);
         }
         else {
             viewport->screenCoordinates(polygon()->outerBoundary(), outerPolygons);
         }
     } else if (ring()) {
         viewport->screenCoordinates(*ring(), outerPolygons);
     }
 }
 
 QPointF BuildingGeoPolygonGraphicsItem::centroid(const QPolygonF &polygon, double &area)
 {
     auto centroid = QPointF(0.0, 0.0);
     area = 0.0;
     for (auto i=0, n=polygon.size(); i<n; ++i) {
         auto const x0 = polygon[i].x();
         auto const y0 = polygon[i].y();
         auto const j = i == n-1 ? 0 : i+1;
         auto const x1 = polygon[j].x();
         auto const y1 = polygon[j].y();
         auto const a = x0*y1 - x1*y0;
         area += a;
         centroid.rx() += (x0 + x1)*a;
         centroid.ry() += (y0 + y1)*a;
     }
 
     area *= 0.5;
     return area != 0 ? centroid / (6.0*area) : polygon.boundingRect().center();
 }
 
 QPointF BuildingGeoPolygonGraphicsItem::buildingOffset(const QPointF &point, const ViewportParams *viewport, bool* isCameraAboveBuilding) const
 {
     qreal const cameraFactor = 0.5 * tan(0.5 * 110 * DEG2RAD);
     Q_ASSERT(m_buildingHeight > 0.0);
     qreal const buildingFactor = m_buildingHeight / EARTH_RADIUS;
 
     qreal const cameraHeightPixel = viewport->width() * cameraFactor;
     qreal buildingHeightPixel = viewport->radius() * buildingFactor;
     qreal const cameraDistance = cameraHeightPixel-buildingHeightPixel;
 
     if (isCameraAboveBuilding) {
         *isCameraAboveBuilding = cameraDistance > 0;
     }
 
     qreal const cc = cameraDistance * cameraHeightPixel;
     qreal const cb = cameraDistance * buildingHeightPixel;
 
     // The following lines calculate the same result, but are potentially slower due
     // to using more trigonometric method calls
     // qreal const alpha1 = atan2(offsetX, cameraHeightPixel);
     // qreal const alpha2 = atan2(offsetX, cameraHeightPixel-buildingHeightPixel);
     // qreal const shiftX = 2 * (cameraHeightPixel-buildingHeightPixel) * sin(0.5*(alpha2-alpha1));
 
     qreal const offsetX = point.x() - viewport->width() / 2.0;
     qreal const offsetY = point.y() - viewport->height() / 2.0;
 
     qreal const shiftX = offsetX * cb / (cc + offsetX);
     qreal const shiftY = offsetY * cb / (cc + offsetY);
 
     return QPointF(shiftX, shiftY);
 }
 
 double BuildingGeoPolygonGraphicsItem::extractBuildingHeight(const GeoDataPlacemark &placemark)
 {
     double height = 8.0;
 
     const OsmPlacemarkData &osmData = placemark.osmData();
 
     QHash<QString, QString>::const_iterator tagIter;
     if ((tagIter = osmData.findTag(QStringLiteral("height"))) != osmData.tagsEnd()) {
         /** @todo Also parse non-SI units, see https://wiki.openstreetmap.org/wiki/Key:height#Height_of_buildings */
         QString const heightValue = QString(tagIter.value()).remove(QStringLiteral(" meters")).remove(QStringLiteral(" m"));
         bool extracted = false;
         double extractedHeight = heightValue.toDouble(&extracted);
         if (extracted) {
             height = extractedHeight;
         }
     } else if ((tagIter = osmData.findTag(QStringLiteral("building:levels"))) != osmData.tagsEnd()) {
         int const levels = tagIter.value().toInt();
         int const skipLevels = osmData.tagValue(QStringLiteral("building:min_level")).toInt();
         /** @todo Is 35 as an upper bound for the number of levels sane? */
         height = 3.0 * qBound(1, 1+levels-skipLevels, 35);
     }
 
     return qBound(1.0, height, 1000.0);
 }
 
 QString BuildingGeoPolygonGraphicsItem::extractBuildingLabel(const GeoDataPlacemark &placemark)
 {
     const OsmPlacemarkData &osmData = placemark.osmData();
 
     auto tagIter = osmData.findTag(QStringLiteral("addr:housename"));
     if (tagIter != osmData.tagsEnd()) {
         return tagIter.value();
     }
 
     tagIter = osmData.findTag(QStringLiteral("addr:housenumber"));
     if (tagIter != osmData.tagsEnd()) {
         return tagIter.value();
     }
 
     return QString();
 }
 
 QVector<BuildingGeoPolygonGraphicsItem::NamedEntry> BuildingGeoPolygonGraphicsItem::extractNamedEntries(const GeoDataPlacemark &placemark)
 {
     QVector<NamedEntry> entries;
 
     const auto end = placemark.osmData().nodeReferencesEnd();
     for (auto iter = placemark.osmData().nodeReferencesBegin(); iter != end; ++iter) {
         const auto tagIter = iter.value().findTag(QStringLiteral("addr:housenumber"));
         if (tagIter != iter.value().tagsEnd()) {
             NamedEntry entry;
             entry.point = iter.key();
             entry.label = tagIter.value();
             entries.push_back(entry);
         }
     }
 
     return entries;
 }
 
 void BuildingGeoPolygonGraphicsItem::paint(GeoPainter* painter, const ViewportParams* viewport, const QString &layer, int tileZoomLevel)
 {
-    Q_UNUSED(tileZoomLevel);
+    // Just display flat buildings for tile level 17
+    if (tileZoomLevel == 17) {
+        if (layer.endsWith(QLatin1String("/frame"))) {
+            AbstractGeoPolygonGraphicsItem::paint(painter, viewport, layer, tileZoomLevel );
+        }
+        return;
+    }
+
+    // For level 18, 19 .. render 3D buildings in perspective
     if (layer.endsWith(QLatin1String("/frame"))) {
         Q_ASSERT(m_cachedOuterPolygons.isEmpty());
         Q_ASSERT(m_cachedInnerPolygons.isEmpty());
         Q_ASSERT(m_cachedOuterRoofPolygons.isEmpty());
         Q_ASSERT(m_cachedInnerRoofPolygons.isEmpty());
         updatePolygons(viewport, m_cachedOuterPolygons,
                                  m_cachedInnerPolygons,
                                  m_hasInnerBoundaries);
         if (m_cachedOuterPolygons.isEmpty()) {
             return;
         }
         paintFrame(painter, viewport);
     } else if (layer.endsWith(QLatin1String("/roof"))) {
         if (m_cachedOuterPolygons.isEmpty()) {
             return;
         }
         paintRoof(painter, viewport);
         qDeleteAll(m_cachedOuterPolygons);
         qDeleteAll(m_cachedOuterRoofPolygons);
         qDeleteAll(m_cachedInnerRoofPolygons);
         m_cachedOuterPolygons.clear();
         m_cachedInnerPolygons.clear();
         m_cachedOuterRoofPolygons.clear();
         m_cachedInnerRoofPolygons.clear();
     } else {
         mDebug() << "Didn't expect to have to paint layer " << layer << ", ignoring it.";
     }
 }
 
 void BuildingGeoPolygonGraphicsItem::paintRoof(GeoPainter* painter, const ViewportParams* viewport)
 {
     bool drawAccurate3D;
     bool isCameraAboveBuilding;
     initializeBuildingPainting(painter, viewport, drawAccurate3D, isCameraAboveBuilding);
     if (!isCameraAboveBuilding) {
         return; // do not render roof if we look inside the building
     }
 
     painter->save();
     QPen const currentPen = configurePainter(painter, viewport);
 
     qreal maxSize(0.0);
     QPointF roofCenter;
 
     // first paint the area (and the outline if there are no inner boundaries)
 
     double maxArea = 0.0;
 
     if ( drawAccurate3D) {
         if (m_hasInnerBoundaries) {
 
             painter->setPen(Qt::NoPen);
             QVector<QPolygonF*> fillPolygons =
                     painter->createFillPolygons( m_cachedOuterRoofPolygons,
                                                  m_cachedInnerRoofPolygons );
 
             foreach( const QPolygonF* fillPolygon, fillPolygons ) {
                 painter->drawPolygon(*fillPolygon);
             }
 
             painter->setPen(currentPen);
 
             foreach( const QPolygonF* outerRoof, m_cachedOuterRoofPolygons ) {
                 painter->drawPolyline( *outerRoof );
             }
             foreach( const QPolygonF* innerRoof, m_cachedInnerRoofPolygons ) {
                 painter->drawPolyline( *innerRoof );
             }
         }
         else {
             foreach( const QPolygonF* outerRoof, m_cachedOuterRoofPolygons ) {
                 painter->drawPolygon( *outerRoof );
             }
         }
     }
     else {
         QPointF const offset = buildingOffset(m_cachedOuterPolygons[0]->boundingRect().center(), viewport);
         painter->translate(offset);
 
         if (m_hasInnerBoundaries) {
 
             painter->setPen(Qt::NoPen);
             QVector<QPolygonF*> fillPolygons = painter->createFillPolygons( m_cachedOuterPolygons,
                                                                    m_cachedInnerPolygons );
 
             foreach( const QPolygonF* fillPolygon, fillPolygons ) {
                 painter->drawPolygon(*fillPolygon);
             }
 
             painter->setPen(currentPen);
 
             foreach( const QPolygonF* outerPolygon,  m_cachedOuterPolygons ) {
                 painter->drawPolyline( *outerPolygon );
             }
             foreach( const QPolygonF* innerPolygon,  m_cachedInnerPolygons ) {
                 painter->drawPolyline( *innerPolygon );
             }
         }
         else {
             foreach( const QPolygonF* outerPolygon,  m_cachedOuterPolygons ) {
                 painter->drawPolygon( *outerPolygon );
             }
         }
         painter->translate(-offset);
 
     }
 
 
     for (int i = 0; i < m_cachedOuterPolygons.size(); ++i) {
         QPolygonF* outerPolygon = m_cachedOuterPolygons[i];
 
         QRectF const boundingRect = outerPolygon->boundingRect();
 
         // Label position calculation
         if (!m_buildingLabel.isEmpty() || !m_entries.isEmpty()) {
             QSizeF const polygonSize = boundingRect.size();
             qreal size = polygonSize.width() * polygonSize.height();
             if (size > maxSize) {
                 maxSize = size;
                 double area;
                 roofCenter = centroid(*outerPolygon, area);
                 maxArea = qMax(area, maxArea);
                 roofCenter += buildingOffset(roofCenter, viewport);
             }
         }
 
         // Draw the housenumber labels
         if (drawAccurate3D && !m_buildingLabel.isEmpty() && !roofCenter.isNull() && !m_cachedOuterRoofPolygons.isEmpty()) {
             QPolygonF * outerRoof = m_cachedOuterRoofPolygons[i];
             double const w2 = 0.5 * painter->fontMetrics().width(m_buildingLabel);
             double const ascent = painter->fontMetrics().ascent();
             double const descent = painter->fontMetrics().descent();
             double const a2 = 0.5 * painter->fontMetrics().ascent();
             QPointF const textPosition = roofCenter - QPointF(w2, -a2);
             if (outerRoof->containsPoint(textPosition + QPointF(-2, -ascent), Qt::OddEvenFill)
                     && outerRoof->containsPoint(textPosition + QPointF(-2, descent), Qt::OddEvenFill)
                     && outerRoof->containsPoint(textPosition + QPointF(2+2*w2, descent), Qt::OddEvenFill)
                     && outerRoof->containsPoint(textPosition + QPointF(2+2*w2, -ascent), Qt::OddEvenFill)
                     ) {
                 painter->drawText(textPosition, m_buildingLabel);
             }
         }
         ++i;
     }
 
     // Render additional housenumbers at building entries
     if (!m_entries.isEmpty() && maxArea > 1600 * m_entries.size()) {
         QBrush brush = painter->brush();
         QColor const brushColor = brush.color();
         QColor lighterColor = brushColor.lighter(110);
         lighterColor.setAlphaF(0.9);
         brush.setColor(lighterColor);
         painter->setBrush(brush);
         foreach(const auto &entry, m_entries) {
             qreal x, y;
             viewport->screenCoordinates(entry.point, x, y);
             QPointF point(x, y);
             point += buildingOffset(point, viewport);
             auto const width = painter->fontMetrics().width(entry.label);
             auto const height = painter->fontMetrics().height();
             QRectF rectangle(point, QSizeF(qMax(1.2*width, 1.1*height), 1.2*height));
             rectangle.moveCenter(point);
             painter->drawRoundedRect(rectangle, 3, 3);
             painter->drawText(rectangle, Qt::AlignCenter, entry.label);
         }
         brush.setColor(brushColor);
         painter->setBrush(brush);
     }
 
     painter->restore();
 }
 
 void BuildingGeoPolygonGraphicsItem::paintFrame(GeoPainter *painter, const ViewportParams *viewport)
 {
     // TODO: how does this match the Q_ASSERT in the constructor?
     if (m_buildingHeight == 0.0) {
         return;
     }
 
     if ((polygon() && !viewport->resolves(polygon()->outerBoundary().latLonAltBox(), 4))
             || (ring() && !viewport->resolves(ring()->latLonAltBox(), 4))) {
         return;
     }
 
     painter->save();
 
     bool drawAccurate3D;
     bool isCameraAboveBuilding;
     initializeBuildingPainting(painter, viewport, drawAccurate3D, isCameraAboveBuilding);
 
     configureFramePainter(painter);
 
     if ( drawAccurate3D && isCameraAboveBuilding ) {
         foreach(QPolygonF* outline, m_cachedOuterPolygons) {
             if (outline->isEmpty()) {
                 continue;
             }
             // draw the building sides
             int const size = outline->size();
             QPolygonF * outerRoof = new QPolygonF;
             outerRoof->reserve(outline->size());
             QPointF & a = (*outline)[0];
             QPointF shiftA = a + buildingOffset(a, viewport);
             outerRoof->append(shiftA);
             for (int i=1; i<size; ++i) {
                 QPointF const & b = (*outline)[i];
                 QPointF const shiftB = b + buildingOffset(b, viewport);
                 // perform backface culling
                 bool backface = (b.x() - a.x()) * (shiftA.y() - a.y())
                         - (b.y() - a.y()) * (shiftA.x() - a.x()) >= 0;
                 if (!backface) {
                     QPolygonF buildingSide = QPolygonF() << a << shiftA << shiftB << b;
                     painter->drawPolygon(buildingSide);
                 }
                 a = b;
                 shiftA = shiftB;
                 outerRoof->append(shiftA);
             }
             m_cachedOuterRoofPolygons.append(outerRoof);
         }
         foreach(QPolygonF* outline, m_cachedInnerPolygons) {
             if (outline->isEmpty()) {
                 continue;
             }
             // draw the building sides
             int const size = outline->size();
             QPolygonF * innerRoof = new QPolygonF;
             innerRoof->reserve(outline->size());
             QPointF & a = (*outline)[0];
             QPointF shiftA = a + buildingOffset(a, viewport);
             innerRoof->append(shiftA);
             for (int i=1; i<size; ++i) {
                 QPointF const & b = (*outline)[i];
                 QPointF const shiftB = b + buildingOffset(b, viewport);
                 // perform backface culling
                 bool backface = (b.x() - a.x()) * (shiftA.y() - a.y())
                         - (b.y() - a.y()) * (shiftA.x() - a.x()) >= 0;
                 if (backface) {
                     QPolygonF buildingSide = QPolygonF() << a << shiftA << shiftB << b;
                     painter->drawPolygon(buildingSide);
                 }
                 a = b;
                 shiftA = shiftB;
                 innerRoof->append(shiftA);
             }
             m_cachedInnerRoofPolygons.append(innerRoof);
         }
     } else {
             // don't draw the building sides - just draw the base frame instead
             QVector<QPolygonF*> fillPolygons = painter->createFillPolygons( m_cachedOuterPolygons,
                                                                    m_cachedInnerPolygons );
 
             foreach( QPolygonF* fillPolygon, fillPolygons ) {
                 painter->drawPolygon(*fillPolygon);
             }
     }
 
     painter->restore();
 }
 
 void BuildingGeoPolygonGraphicsItem::screenPolygons(const ViewportParams *viewport, const GeoDataPolygon *polygon,
                                                     QVector<QPolygonF *> &innerPolygons,
                                                     QVector<QPolygonF *> &outerPolygons
                                                     )
 {
     Q_ASSERT(polygon);
 
     viewport->screenCoordinates( polygon->outerBoundary(), outerPolygons );
 
     QVector<GeoDataLinearRing> const & innerBoundaries = polygon->innerBoundaries();
     foreach (const GeoDataLinearRing &innerBoundary, innerBoundaries) {
         QVector<QPolygonF*> innerPolygonsPerBoundary;
         viewport->screenCoordinates(innerBoundary, innerPolygonsPerBoundary);
 
         innerPolygons.reserve(innerPolygons.size() + innerPolygonsPerBoundary.size());
         foreach( QPolygonF* innerPolygonPerBoundary, innerPolygonsPerBoundary ) {
             innerPolygons << innerPolygonPerBoundary;
         }
     }
 }
 
 void BuildingGeoPolygonGraphicsItem::configureFramePainter(GeoPainter *painter) const
 {
     GeoDataStyle::ConstPtr style = this->style();
     if (!style) {
         painter->setPen( QPen() );
     }
     else {
         const GeoDataPolyStyle& polyStyle = style->polyStyle();
         const QColor transparentColor(Qt::transparent);
 
         painter->setPen(Qt::NoPen);
 
         if (!polyStyle.fill()) {
             painter->setBrush(transparentColor);
         }
         else {
             const QColor paintedColor = polyStyle.paintedColor();
             painter->setBrush(paintedColor.darker(150));
         }
     }
 }
 
 }